BFNA Title: Lejeuneaceae
Author: B. M. Thiers
Date: May 13, 2016
Edit Level: R
Version: 1

Bryophyte Flora of North America, Provisional Publication
Missouri Botanical Garden
BFNA Web site: http://www.mobot.org/plantscience/BFNA/bfnamenu.htm

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XX. LEJEUNEACEAE Casares-Gil

Barbara M. Thiers

Plants differentiated dorsiventrally, spreading from substrate or forming mats, prostrate, or with some ascending or pendent branches. Branches always subtending lateral leaves, either replacing the basiscopic portion of a leaf (Frullania-type branch), or produced below the entire leaf, with branch base surrounded by a collar of cells (Lejeunea-type branch) or without a collar (Aphanolejeunea-type branch).  Lateral leaves alternate, with dorsal lobe incubous, ventral lobe (lobule) succubous, lobe plane, with lobule folded under the dorsal lobe, usually attached to both lobe and stem, forming in most cases a lobule visible only in ventral view, lobule free margin entire or toothed; oil bodies present; ocelli sometimes present.  Underleaves present or absent; when present, 2-lobed or entire.   Rhizoids confined to underleaf base (if underleaves absent, rhizoids confined to place on stem where underleaf would have developed), sometimes originating from a distinctly defined region (rhizoid disc).  Specialized asexual reproduction by deciduous leaves or branches, or multicellular discoid gemmae. Androecia terminal on main stems or on separate branches, consisting of paired, saccate bracts, each bract containing 1--2 spherical, colorless antheridia, stalk 1-seriate, bracteoles sometimes present throughout the androecium, sometimes present only at the base.  Gynoecium terminal on an ordinary leafy branch or on a short lateral branch, consisting of 1--6 bract cycles (paired bracts plus bracteole) surrounding 1 archegonium; branches subtending gynoecial bracts (gynoecial innovations) usually present; innovation leaf sequence beginning with a lateral leaf (lejeuneoid sequence) or with an underleaf (pycnolejeuneoid sequence); perianths well developed, terete or dorsiventrally compressed, usually with 3--5 longitudinal folds or keels, keels sometimes modified into terete horns; mouth abruptly contracted to a short beak, perigynium absent.  Sporophyte foot discoid, small; seta to ca 3 mm long, sometimes articulated, outer cell rows 12 or 16, inner cell rows 4; capsule barely exerted, spherical, 4-valved, wall 2-layered; elaters trumpet-shaped, with 1--2 weak spiral thickenings, or with no spiral thickenings, attached near valve apex; spores green, multicellular, surface granulose with scattered rosettes of triangular tubercles.

Genera 68, species ca. 1000 (16 genera and 65 species in the flora): North America, Mexico, West Indies, Bermuda, Central America, South America, Eurasia, Africa, Atlantic Islands, Indian Ocean Islands, Pacific Islands, Australia.

Lejeuneaceae is the largest family of Jungermanniales, and is most speciose and abundant in tropical regions.  In North America the family is largely restricted to the southeastern United States, where plants occur usually on tree trunks or branches, less commonly on decorticated wood or rock, and occasionally on living leaves. The Lejeuneaceae is a member of the Porellales, one of the two major lineages of Jungermanniopsida subclass Jungermanniidae, or leafy liverworts, and is most closely related to the Jubulaceae (J. Heinrichs et al. 2005). Similarities of the Lejeuneaceae to the Jubulaceae are the presence of both Frullania- and Lejeunea-type vegetative branches, a small sporophyte foot, and trumpet-shaped elaters that are always attached to the capsule valves.  The most distinctive features of the Lejeuneaceae are the complicate-bilobed leaves, where the smaller ventral lobule is fused to the stem to form pocket or sac, the single archegonium surrounded by a cylindrical perianth that is subtended by one (rarely two) cycles of bracts.

Classically Lejeuneaceae were divided into three major morphological groups, based largely on underleaf features: the Lejeuneoideae (or Schizostipae) for species with one biobed underleaf per pair of lateral leaves; the Pytchanthoideae (or Holotstipae) for species with one entire underleaf per pair of lateral leaves, and the Cololejeuneoideae (or Paradoxae) with either one underleaf per lateral leaf or no underleaves at all.  Representatives of all three groups occur in North America.  Using an expanded morphological character set, R. M. Schuster (1963, 1980) recognized seven subfamilies of Lejeuneaceae.   However, molecular evidence suggests that the Cololejeuneoideae and Lejeuneoideae form one lineage, and that the Ptychanthoideae is polyphyletic (J. Heinrichs et al. 2005; R. Wilson et al. 2002).  From a combination of molecular and morphological character analysis, a comprehensive new classification of Lejeuneaceae has emerged (S. Gradstein 2013; L. Söderström et al. 2016).  In this classification, the family is now divided into two subfamilies, Ptychanthoideae (19 genera) and Lejeuneoideae (49 genera).  Lejeuneoideae is further subdivided into three tribes and eight subtribes.  To maximize the utility of this treatment for non-specialists in the family, I have chosen to use no subfamilial classification.  For the key, I have  grouped the genera based on the most obvious morphological differences among the genera---the underleaves (or lack thereof).  The current systematic position is discussed in each generic treatment.  

SELECTED REFERENCES   Evans, A. W.  1902.  The Lejeuneae of the United States and Canada.  Mem. Torrey Bot. Club 8: 113--183.   Gradstein, S. R. 2013.  A classification of Lejeuneaceae (Marchantiophyta) based on molecular and morphological evidence.  Phytotaxa 100: 6--20.  Gradstein, S. R., M. E. Reiner-Drehwald, and H. Schneider.  2003.  A phylogenetic analysis of the genera of Lejeuneaceae (Hepaticae).  Bot. J. Linn. Soc. 143: 391--410.  Heinrichs, J., S. R. Gradstein, R. Wilson, and H. Schneider.  2005.  Towards a natural classification of liverworts (Marchantiophyta) based on the chloroplast gene rbcL.  Cryptogamie Bryologie 26:131--150.  Schuster, R. M.  1963.  An annotated synopsis of the genera and subgenera of Lejeuneaceae.  Beih. Nova Hedwigia 9: 1--203.  Schuster, R. M.  1980.  Lejeuneaceae.  In: R. M. Schuster.  1966--1993.  Hepaticae and Anthocerotae of North America.  New York.  Vol. 4, pp. 706--1314.  Söderström, L., et al.  2016.  World checklist of hornworts and liverworts.  Phytokeys 59: 1--828.  Wilson, R., S. R. Gradstein, H. Schneider, and J. Heinrichs.  2007.  Unraveling the phylogeny of the Lejeuneaceae (Jungermanniopsida): Evidence for four main lineages.  Mol. Phylog. Evol. 43: 270--282.

1.  Plants lacking underleaves ………………………………….….… 5. (Cololejeunea)

1.  Plants with underleaves.

3.  Underleaves unlobed or weakly notched; brownish secondary pigmentation often present…………………………..Key To Genera With Entire Underleaves

3.  Underleaves 2-lobed; brownish secondary pigmentation absent (but present in Ceratolejeunea)………………………… Key To Genera With Two-Lobed Underleaves

KEY TO GENERA WITH ENTIRE UNDERLEAVES

1.  Lobule free margin flattened and visible for entire length, with 3--6 distinct and similarly shaped teeth, each composed of 1--3 cells; perianths with 6 or more keels, not dorsiventrally compressed.

2.  Plants appearing yellow to golden brown due to secondary pigmentation; upright branches with deciduous leaves usually present; gynoecial bract keels without auriculate wing at base; gynoecial innovations (i.e., branches subtending gynoecial branches) absent ……….………………………………1.  Acrolejeunea

2.  Plants appearing blackish due to secondary pigmentation; upright branches with deciduous leaves absent; gynoecial bract keels with an auriculate wing at base; gynoecial innovations  present, usually two per gynoecium (i.e., one subtending each bract) …………………………………………… 8.  Frullanoides

1.  Lobule free margin inrolled for at least half the length, with 0--3 teeth (if more than  one tooth, then teeth dissimilar in size and shape);  perianths with 2--5 keels.

3.  Plants pure green or yellow-green, lacking secondary pigmentation; lobular hyaline papilla produced on the free lobule margin, not displaced toward inner surface of lobule.

4. Underleaves and gynoecial bracts retuse to emarginate at apex; hyaline papilla at proximal base of lobule free margin tooth; oil bodies numerous, small and homogenous; perianths with 3 longitudinal keels; gynoecial innovations absent…………………….………………2.  Caudalejeunea

4.  Underleaves and gynoecial bracts entire; hyaline papilla at distal base of lobule free margin tooth; oil bodies one per cell, large, botyroidal; perianths with 5 longitudinal keels; gynoecial innovations present

………………………………………………….4.  Cheilolejeunea, in part

3.  Plants appearing brown or black due to secondary pigmentation; lobular hyaline papilla inserted on inner surface of lobule.

5.  Lobule free margin tooth longer than wide, hook-shaped and sharply pointed; leaf cell walls without intermediate thickenings; oil bodies very large, with a finely granulose surface; androecium with bracteoles at the base only; perianths with 2 keels forming auriculate “shoulders” that extend beyond the perianth apex ……………………15.  Neurolejeunea

5.  Lobule free margin tooth not or only slightly longer than wide, straight, and bluntly pointed; leaf cell walls with intermediate thickenings; oil bodies small to large, smooth or botryoidal; androecium with bracteoles throughout; perianths with 3 keels forming longitudinal folds extending at least half the perianth the length.

6.  Underleaves orbiculate to reniform in outline, upper and lateral margins plane; trigones in cells of leaf midportion triangular (no sides bulging); oil bodies small, smooth; perianths 5-keeled, dorsiventrally flattened, keels dentate to laciniate; gynoecial bract margin irregular to distinctly dentate ………….12.  Lopholejeunea

6.  Underleaves obdeltate in outline, upper and lateral margins often narrowly recurved; trigones in cells of leaf midportion  cordate (2 sides bulging, one side concave); oil bodies large, botryoidal; perianths 3-keeled triangular in cross-section (not flattened), keels entire; gynoecial bract margin entire …

…………..……………………………….. 13.  Mastigolejeunea

KEY TO GENERA WITH TWO-LOBED UNDERLEAVES

1.  Underleaves as many as lateral leaves ……………………….…6. Diplasiolejeunea

1.  Underleaves half as many as lateral leaves.

2.  Lateral leaf lobes without ocelli.

3.  Plants green to olive- or brownish green; stem epidermal cells not or slightly larger than inner cells; hyaline papilla of lobule margin distal to marginal tooth; cells of underleaf base uniform in size and shape. Oil bodies usually large, 1--3 per cell ……..…..…4. Cheilolejeunea

3. Plants green to whitish or yellowish green; stem epidermal cells distinctly larger than inner cells; hyaline papilla of lobule margin proximal to marginal tooth; flanking cells of underleaf base (i.e., the basalmost marginal cell on each side of stem) often larger and more distinctly rounded in outline than other underleaf basal cells. Oil bodies usually smaller and more than 3 per cell ……………………10.  Lejeunea

2. Lateral leaf lobes with one or more ocelli either solitary, clustered at leaf base, forming a line in the leaf midportion or scattered throughout leaf.

4.  Underleaves widest at the apex, lobes parallel to divergent.

5.  Underleaf lobes more than one cell wide, lobe apex broadly rounded; ocelli at leaf base; gynoecial innovations present, innovation leaf sequence beginning with a lateral leaf (lejeuneoid sequence) ………………………………….…9.  Harpalejeunea

5.  Underleaf lobes one cell wide, lobe apex narrowly acute; ocelli in leaf midportion; gynoecial innovations present or absent, if present, leaf sequence beginning with an underleaf (pycnolejeuneoid sequence).

6.  Plants with an anise-like odor; underleaf base bordered by cells that are distinctly larger than interior cells; lobule marginal tooth isodiametric and bluntly pointed, weakly differentiated from other marginal cells; gynoecial innovations absent ………….…………11.  Leptolejeunea

6. Plants with no perceptible odor; marginal cells of underleaf base not distinctly larger than interior cells; lobule free margin tooth elongate and sharply pointed, strongly differentiated from other marginal cells; gynoecial innovations present………………….…7. Drepanolejeunea

4.  Underleaves widest at the middle, lobes parallel to connivent.

7.  Plants reddish brown or in shade dark olive; leaf cells with a distinct brown middle lamella; lobules of leaves at branch base sometimes utriculate (strongly inflated); lobule free margin tooth isodiametric and bluntly pointed;  perianth keels forming terete, horn-like projections ………….….........…3. Ceratolejeunea

7.  Plants green to olive green; middle lamella of leaf cells  colorless; utriculate lobules absent; lobule free margin tooth elongate, straight or curved, sharply pointed; perianth keels forming longitudinal folds.

8.  Plants up to 1 mm wide; flagelliform stems present, bearing closely imbricate leaves with deciduous lobes; ocelli numerous, scattered  in leaf lobe and/or at leaf base; gynoecial innovation leaf sequence beginning with an underleaf (Pycnolejeunea-type) ……...…16,  Rectolejeunea

8.   Plants up to 0.5 mm wide; flagelliform absent; ocelli only 1--3, restricted to lobe base; gynoecial innovation leaf sequence beginning with a lateral leaf  (Lejeunea-type) ……........................................................14. Microlejeunea

1.  ACROLEJEUNEA  (Spruce) Schiffner in A. Engler & G. Prantl, Nat. Pflanzenfam. 1,3: 119, 128.  1893 *  [Greek acro, highest point (alluding to terminal gynoecia on long shoots, i.e., without subtending innovational braches), and Lejeunea, the name of a related genus]

Lejeunea subg. Acrolejeunea Spruce, Trans. & Proc. Bot. Soc. Edinburgh, 15: 115. 1884; Ptychocoleus  Trevis

Plants up to 2 mm wide; forming appressed mats with some ascending, flagelliform branches; yellowish to golden brown or green. Branches Lejeunea- or rarely Frullania-type.  Stem composed of 10--22 epidermal surrounding 17--40 inner cells, epidermal cells larger.  Lateral leaf insertion J-shaped, dorsal insertion longer than ventral, more than 5 leaf cells attached to stem; leaves convolute, suberect and wrapped around stem when dry, squarrose when moistened, imbricate; lobe ovate-falcate to oblong-falcate; cells of midportion longer than wide, cell wall middle lamella colorless, trigones large, cordate, intermediate thickenings usually present; oil bodies 7--12 or more per cell, small, fusiform to ellipsoidal, surface smooth; ocelli absent.  Lobule always fully formed, ovate to orbicular, 0.4--0.5 lobe length, inflated along keel but sharply flattened above, free margin plane throughout, with 1--9 marginal teeth, all similar in size and shape, 1-celled, (teeth dissimilar in size) bluntly pointed, hyaline papilla on the inner surface of the lobule, stylus absent.  Underleaves produced in a 1:2 ratio with lateral leaves, inserted across 4--6 (occasionally up to 10) stem cells, entire, contiguous to imbricate, broadly orbicular to reniform, 3 times stem width, margins entire, plane, base rounded, cells of underleaf base uniform in size; stylus absent.  Specialized asexual reproduction by deciduous lobes on leaves of ascending branches.  Sexual condition autoicous or dioicous.  Androecia on terminal or intercalary long branches, bracteoles present throughout.  Gynoecial innovations absent; bracts in 1--6 pairs, increasing in size with proximity to gynoecium, margin entire, keel rounded, not winged; perianth oblong to obovoid, inflated, keels 5--10, forming longitudinal folds extending entire perianth length.

Species 21 (1 in the flora): United States, Mexico, West Indies, Bermuda, Central America, South America, Eurasia, Africa, Atlantic Islands (including Macaronesia), Indian Ocean Islands, Pacific Islands (including Hawaii and New Zealand), Australia.

The most distinctive features of Acrolejeunea are the golden-brown color, multiple lobule teeth, the absence of gynoecial innovations and pluriplicate perianths.  In his monograph of the genus, S. R. Gradstein (1975) recognized two subgenera based on the presence or absence of asexual reproduction by deciduous leaf lobes.  The North American A. heterophylla belongs to subgenus Acrolejeunea.  R. M. Schuster (1980) and S. R. Gradstein (1994) considered Acrolejeunea to be most closely related to Frullanoides, but Acrolejeunea is currently placed in subfamily Ptychanthoideae with other regional genera Caudalejeunea, Frullanoides, Lopholejeunea, and Mastigolejeunea (L. Söderström et al.  2016).

SELECTED  REFERENCES  Evans, A. W.  1908.  Hepaticae of Puerto Rico IX.  Brachiolejeunea, Ptychocoleus, Archilejeunea, Leucolejeunea, and Anoplolejeunea.  Bull. Torrey Bot. Club  35: 155--179.   Gradstein, S. R.  1975.  A taxonomic monograph of the genus Acrolejeunea.  Bryophyt.  Biblioth. 4: 1--162.   Gradstein, S. R.  1994. Acrolejeunea.  In: Lejeuneaceae:  Ptychantheae, Brachiolejeuneae.  Flora Neotropica Monograph 62: 124--130.  Schuster, R. M.  1980.  Acrolejeunea.  In: R. M. Schuster.  1966--1993.  Hepaticae and Anthocerotae of North America.  New York. Vol. 4, pp. 790--798.

1. Acrolejeunea heterophylla (A. Evans) Grolle & Gradstein in S. R. Gradstein, J. Hattori Bot. Lab. 38: 332.  1974

Ptychocoleus heterophyllus Evans, Amer. J. Bot. 5: 44.  1918

Lateral leaf lobe ovate to suborbicular, 0.7--0.9 x 0.45--0.6 mm, apex broadly rounded, margin entire, incurved on the lower edge near lobule insertion.  Lobule free margin with 4--8 teeth, apex attenuate, sinus between distalmost tooth and lobule apex straight to shallowly arched. Specialized asexual reproduction by deciduous leaf lobes on ascending branches. Sexual condition dioicous.  Gynoecial bracts in 3--5 pairs, innermost bract apex narrowly rounded, margin plane; perianth exerted for less than 0.5 length, with up to 10 keels.

On bark of living trees; humid and dry forests; low elevations; Fla.; West Indies; Central America.

Acrolejeunea heterophylla is similar to Frullanoides corticalis and F. bahamensis in the multiple, similarly shaped, 1--3 celled teeth on the lobule free margin and the pluriplicate perianths.    However, A. heterophylla is brown rather than black, has deciduous leaf lobes on ascending branches, and lacks gynoecial innovations and wings on the keels of the gynoecial bracts.

2.  CAUDALEJEUNEA Stephani ex Schiffner in Engler & Prantl, Nat. Pflanzenfam. 1,3: 129.  1893 *  [Greek cauda, a tail, alluding to arching secondary branches, and Lejeunea, the name of a related genus]

Plants up to 2.5 mm wide; primary stems forming tightly appressed mats, secondary stems arching away from substrate; pale to bright green to yellowish brown.  Branches Lejeunea type.  Stem composed of 12--14 epidermal surrounding 16--20 inner cells, epidermal cells larger. Lateral leaf insertion J-shaped, dorsal insertion longer than ventral, more than 5 leaf cells attached to stem, leaves spreading when dry, plane to slightly convex when moistened, imbricate; lobe narrowly oblong to ovate; cells of leaf midportion longer than wide, cell wall middle lamella colorless, trigones large, cordate, intermediate thickenings present, 1--2 per wall; oil bodies 20--28 per cell, small, fusiform, surface smooth; ocelli absent.  Lobule fully formed or reduced, ovoid-oblong, 0.30--0.4 lobe length, convex proximally, plane distally, inrolled for 0.75--0.9 length, 0--3 marginal teeth up to 4 cells long, 1--3 cells wide at base, triangular, bluntly to sharply pointed, hyaline papilla at proximal base of tooth closest to lobule apex; stylus absent.  Underleaves produced in a 1:2 ratio with lateral leaves, inserted across 4 stem cells, ca. 3 times stem width, imbricate, entire, ovate to obdeltoid to suborbicular, upper margin entire or emarginate, upper and lateral margins plane, base cuneate, slightly decurrent, cells of underleaf base uniform in size.  Specialized asexual reproduction by discoid gemmae produced from dorsal surfaces of leaf cells.  Sexual condition autoicous [dioicous].  Androecia usually terminal on a long branch, bracteoles present throughout.  Gynoecial innovations absent; bracts in one pair, not or slightly larger than lateral leaves, margins irregularly dentate, keel sharply folded, not winged; perianth obdeltoid, inflated, keels 3 [compressed and with 3--10 folds in the upper half ] forming sharp longitudinal folds that extend almost entire perianth length. 

Species 13 (1 in the flora): North America, Mexico, West Indies, Bermuda, Central America, South America, Africa, Atlantic Islands, Indian Ocean Islands, Pacific Islands (including Hawaii), Australia.

Caudalejeunea is quite distinct from other North American genera of Lejeuneaceae in the combination of entire underleaves in the lack of brown or black secondary pigmentation, discoid gemmae, no gynoecial innovations, and 3-keeled perianths.  R. M. Schuster (1980) recognized three subgenera of Caudalejeunea, only one of which, subgen. Caudalejeunea, with type species C. lehmanniana, occurs in the Americas.   Caudalejeunea is currently placed in subfamily Ptychanthoideae, with other regional genera Acrolejeunea, Frullanoides, Lopholejeunea and Mastigolejeunea (Söderström, L., et al.  2016). The greatest species diversity for this genus is in Africa (C. VandenBergen 1984).

SELECTED REFERENCES    Evans, A. W.  1907.  Hepaticae of Puerto Rico VIII.  Symbiezidium, Marchesinia, Mastigolejeunea, Caudalejeunea, Bryopteris.  Bull. Torrey Bot. Club 34: 533--568.   Gradstein, S. R. 1994.  Caudalejeunea.  In:  Lejeuneaceae:   Ptychantheae, Brachiolejeuneae.  Flora Neotropica Monograph 62: 120--124.  Schuster, R. M.  1980.  Caudalejeunea.  In: R. M. Schuster.  1966--1993.  Hepaticae and Anthocerotae of North America.  New York. Vol. 4, pp. 774--784.   VandenBerghen, C.  1984.  Le genre Caudalejeunea (Steph.) Schiffn. en Afrique.  Cryptogamie, Bryologie et Lichénologie 5: 99--109. 

1. Caudalejeunea lehmanniana (Gottsche) A. Evans, Mem. Torrey Bot. Club 34: 544, plate 33.  1907

Lejeunea lehmanniana Gottsche in C. M. Gottsche, J. B. W. Lindenberg & C. G. D. Nees, Syn. Hepat., 325.  1845

Plants 1.5--2 mm wide.  Lateral leaf lobe oblong-ovate to narrowly ovate, 0.50--0.77 x 1--1.5 mm, margin entire to irregularly toothed; apex acutely to obtusely pointed, acroscopic base rounded, basiscopic lobe straight to rounded, plane.  Lobule apex attenuate, sinus between lobule tooth and apex elongate and sinuous. Gynoecial bract lobe ovate-lanceolate, apex acute to apiculate or acuminate, lobule very small, ligulate to rectangular, bracteole ovate, apex sharply acute, 2-lobed for 0.1--0.2 bracteole length, base cuneate to rounded; perianth exerted for less than 0.5 perianth length.

On bark of living trees or on living leaves; humid forests; low elevations; Fla; West Indies; Bermuda; Central America; South America.

The suite of characters exhibited by C. lehmanniana make it relatively easy to distinguish from similar species, namely the lack of secondary pigmentation, the emarginate underleaves, the discoid gemmae, lack of gynoecial innovations and the 3-keeled perianths.

3.  CERATOLEJEUNEA J. B. Jack & Stephani, Hedwigia 31: 16.  1892 *  [Greek keras, horn, and Lejeunea, a related genus]

Plants 1--1.5 mm wide; tightly appressed to substrate; microphyllous branches occasionally present; brown to reddish brown.  Stems with 7 epidermal cells surrounding 10--20 inner cells, epidermal cells distinctly larger.  Lateral leaf insertion J-shaped, dorsal insertion longer than ventral, more than 5 leaf cells attached to stem; leaves widely spreading when dry, plane to convex when moist, imbricate; lobe ovate to ovate-falcate, apex bluntly rounded; trigones small to large, triangular to cordate, intermediate thickenings sometimes present, cell walls with a brown middle lamella; oil bodies 3--5 per cell, oblong, small to moderate in size, segmented to botryoidal; ocelli usually present, 1--5 per leaf, basal or grouped in leaf midportion.  Lobule fully formed or reduced, usually ovoid, 0.3--0.5 lobe length, convex proximally, plane distally, free margin inrolled for 0.7--0.9 lobule length, with 1 single-celled, often falcate tooth, lobules at stem bases sometimes utriculate (i.e., as large as leaf lobe, strongly inflated with free margin strongly inrolled for entire length), hyaline papilla at its proximal base; stylus absent.    Underleaves produced in a 1:2 ratio with lateral leaves, distant to contiguous, ovate to orbiculate, 2-lobed, 1--2 times stem length; lobes parallel, triangular, lateral margins entire, base cuneate to rounded, cells of underleaf base uniform in size.  Specialized asexual reproduction rare (caducous leaf lobes and leaf margin regeneration in C. laetefusca).  Sexual condition autoicous or dioicous.  Androecia usually on short branches, bracteoles at base only.  Gynoecia on short or long branches, innovations single or paired, leaf sequence pycnolejeuneoid; bracts in one pair, somewhat larger than lateral leaves, margin entire to irregularly dentate, keel rounded to acutely folded, not winged;  perianth obovoid, inflated, with 4 keels forming shoulderlike crests or terete horns that extend beyond apex of perianth.

Species 40 (3 in the flora): North America, Mexico, West Indies, Bermuda, Central America, South America, Africa, Atlantic Islands (including Macaronesia), Indian Ocean Islands, Pacific Islands (including Hawaii but not New Zealand), Australia.

Ceratolejeunea is generally easily distinguished from other Lejeuneaceae subfamily Lejeuneoideae by the dark color of the plants, presence of ocelli, utriculate lobules, and the horned perianths, although not all species possess all of these features.  G. Dauphin (2003) recognized two subgenera (Ceratolejeunea and Caducifolia).  All of the North American species belong to subgenus Caducifolia.  Ceratolejeunea is currently placed in subfamily Lejeuneoideae, tribe Lejeuneeae subtribe Ceratolejeuneinae.  It is the sole member of this subtribe.

SELECTED REFERENCES   Dauphin, G.  2003.  Ceratolejeunea.  Flora Neotropica Monographs 90: 1--86.  Fulford, M.  1944.  Studies on American Hepaticae--VI. Ceratolejeunea.  Brittonia 5: 368--403.   Schuster, R. M.  1980.  Ceratolejeunea.  In: R. M. Schuster.  1966--1993.  Hepaticae and Anthocerotae of North America.  New York. Vol. 4, pp. 909--929.

1. Ocelli forming a line extending from base to leaf midportion…………………..

      ……………………………..………………………3.  Ceratolejeunea ceratantha

     1. Ocelli basal or absent.

2.  Perianth keels forming crests (rather than distinct horns); plants usually dioicous;  leaf margins entire; utriculate lobules absent; asexual reproduction by regeneration from leaf margin or by dehiscent leaf lobes sometimes present……………………...

………………………………………………………….2. Ceratolejeunea laetefusca

2.  Perianth keels forming terete horns; plants autoicous or dioicous; leaf margins entire or irregularly dentate near leaf apex;  utriculate lobules often present at branch bases, asexual reproduction absent ……...………1. Ceratolejeunea cubensis

1. Ceratolejeunea cubensis (Montagne) Schiffner in A. Engler & K. Prantl, Nat. Pflanzenfam. 1(3): 125.  1893

Lejeunea cubensis Montagne in Sagra, Hist. Phys. Cuba (Bot., Pl. Cell.), 481. 1842

Plants yellowish or reddish brown when dry.  Lateral leaf lobe ovate, sometimes somewhat falcate, margin, entire or weakly toothed near apex, apex rounded to broadly or sharply acute, sometimes incurved when dry; ocelli, 0--5 in cluster (i.e., ocelli adjacent along long axis) at leaf base. Utriculate lobules occasionally present at branch bases.  Sexual condition autoicous or dioicous.  Perianth obovoid, 4 keels forming smooth triangular horns with tapering tips, dorsal keel absent.

Bark of living trees, on decorticated wood, or creeping over living filmy ferns and decorticated wood in humid, restricted to densely vegetated "islands" of subtropical forest (i.e., hammocks) in South Florida; 0--10 m; Fla.; Mexico; West Indies; Bermuda; Central America; South America.

Ceratolejeunea cubensis can be distinguished from C. laetefusca by the usual presence of at least a few weak teeth on the margin, and the perianth keels form distinct horns rather than crests.  Also, C. cubensis is usually autoicous, and utriculate lobules are sometimes present at branch bases. Dehiscent leaves are lacking in C. cubensis. 

2. Ceratolejeunea laetefusca (Austin) R. M. Schuster, J. Elisha Mitchell Sci. Soc. 72: 306.  1956

Lejeunea laetefusca Austin, Bot. Gaz. (Hanover). 1: 36. 1876

Plants light to olive brown when dry.  Lateral leaf lobe ovate, sometimes slightly falcate, margin entire, irregular or crenulate, apex rounded rarely toothed, plane when dry; ocelli consistently present, 1--5 in a cluster (i.e., ocelli adjacent along long axis) at leaf base.  Utriculate lobules absent.  Specialized asexual reproduction sometimes present, by dehiscent leaves or by plant regeneration from leaf margin cells.  Sexual condition dioicous, rarely autoicous.  Perianth ellipsoid, 4 keels forming smooth flattened, sharply-angled crests (horns absent), dorsal keel sometimes present as weak fold.

Bark of living trees; evergreen forests in moist subtropical portions of se Coastal Plain; low elevations; Fla., Ga., La., Miss., S.C.; West Indies; Central America; South America.

Ceratolejeunea laetefusca is the most common species of the genus in North America.  It is rarely found with mature perianths, and sterile plants growing in deep shade might be mistaken for a species of Cheilolejeunea.  Careful observation of the hyaline papilla should resolve any confusion, however, because the papilla is proximal to the marginal tooth in Ceratolejeunea, but distal in Cheilolejeunea. The brown pigmentation, usually present in C. laetefusca will also usually distinguish it from other Lejeuneaceae with 2-lobed underleaves.   Although C. guianensis has been reported from the U.S. by M. Fulford (1945), and rather tentatively by G. Dauphin (2003), no specimens observed for this study could be referred to C. guianensis.  G. Dauphin (2003) differentiated C. guianensis from C. laetefusca by are the presence of flagelliform branches and leaves incurved when dry, but also stated that these differences are not sufficient to separate the taxa.

3.   Ceratolejeunea ceratantha (Nees & Mont.) Schiffner, Bot. Jarhb.23: 582.  1897

Lejeunea ceratantha Nees & Montagne, Ann. Sci. Nat., Bot., sér. 2.  Bot. 14: 335. 1840

Plants reddish brown when dry.  Lateral leaf lobe asymmetrically ovate, somewhat falcate, margin entire to crenate or toothed on antical margin and leaf apex, apex rounded to sharply acute, plane; ocelli usually present, 2--5 in a line (i.e., adjacent ocelli joined along short axis) extending from leaf base into leaf midportion.  Utriculate lobules occasionally present at branch bases.  Sexual condition autoicous.  Perianth obovoid, keels forming 4 triangular horns with tapered or inflated tips, surface crenuate, dorsal keel absent.

Bark at base of living trees; humid, densely vegetated "islands" of subtropical forest (i.e., hammocks); low elevations; Fla.; West Indies; Central America.

Ceratolejeunea ceratantha is known from only two scanty and depauperate collections in Florida, both of which were treated by R. M. Schuster (1980) as C. rubiginosa Steph. The Florida collections exhibit an entire to weakly dentate leaf margin and the ocelli are single or absent in some leaves, or may form a broken line in the leaf midportion, characters that fit better with C. ceratantha, as G. Dauphin (2003) attested.   Ceratolejeunea rubiginosa is characterized by ocelli in an unbroken line and distinct dentations  along the leaf margin. 

OTHER REFERENCES  Schuster, R. M.  1963.  An annotated synopsis of the genera and subgenera of Lejeuneaceae.  Nova Hedwigia Beih. 9: 1--203.   Schuster, R. M.  1984.  Evolution, Phylogeny and Classification of the Hepaticae.  In: R. M. Schuster, ed.  1984.  New Manual of Bryology.  Vol. 2, pp. 892--1070.  Nichinan, Japan.

4.  CHEILOLEJEUNEA  (Spruce) Schiffner in A. Engler & K. Prantl, Nat. Pflanzenfam. 1(3): 124.  1893 * [Greek cheilos, lip, alluding to tendancy for old perianths to split along the lateral keels, forming two lobes, or lips, and Lejeunea, a related genus]

Euosmolejeunea (Spruce) Schiffner, Leucolejeunea A. Evans

Plants 0.2--2 mm wide; forming loosely interwoven to tightly appressed mats, microphyllous branches sometimes present; pale to olive green to when dry.  Branches Lejeunea-type.  Stems with 7 epidermal cells surrounding 10--30 inner cells, epidermal cells not or slightly larger.  Lateral leaf insertion J-shaped, dorsal insertion longer than ventral, more than 5 leaf cells attached to stem; leaves leaves narrowly to widely spreading when dry, plane to slightly convex when moistened, contiguous to imbricate; lobe orbicular to ovate or ovate-falcate, apex rounded; cells of leaf midportion isodiametric to slightly longer than wide, cell wall middle lamella colorless, trigones small to large, triangular to cordate, intermediate thickenings sometimes present; oil bodies usually 1--6 per cell, very large, botryoidal; ocelli absent.  Lobule always fully formed, ovoid, 0.2--0.7 lobe length, convex proximally, plane distally, free margin inrolled for about 0.5 --0.9 lobule length, with 1 single-celled tooth, blunt or pointed, hyaline papilla at its distal base; stylus absent.  Underleaves produced in a 1:2 ratio with lateral leaves, inserted across 2 stem cells, distant to contiguous, entire or 2-lobed, ovate to orbicular, 1--4 times stem length; lobes parallel, triangular, lateral margins entire, base cuneate to auriculate, cells of underleaf base uniform in size. Specialized asexual reproduction in some species by caducous leaf lobes.  Sexual condition autoicous or dioicous.  Androecia on short or long branches, bracteoles at base only.  Gynoecia on short or long branches, innovations usually present, single or occasionally paired, leaf sequence lejeuneoid or pycnolejeuneoid, sterile or fertile; bracts in one pair, somewhat larger than lateral leaves, margin entire, keel rounded to acutely folded, not winged; perianth obdeltoid to obclavate, not or slightly dorsiventrally flattened, keels 4--5, forming longitudinal folds that extend 0.3--0.5 perianth length, smooth. 

Species ca. 150  (10 in the flora): North America, Mexico, West Indies, Bermuda, Central America, South America, Africa, Atlantic Islands (including Macaronesia), Indian Ocean Islands, Pacific Islands (including Hawaii and New Zealand), Australia.

Although the position of the hyaline papilla is the most definitive feature differentiating Cheilolejeunea from Lejeunea, this can be a difficult character to observe, requiring careful dissection and flattening of the lobule so it can be mounted on a microscope slide for observation at a magnification of 200--400 times.  If it is not possible to observe this character, secondary characters that may help to distinguish the two genera are color (plants usually bright green or yellow green in Lejeunea, dark or brownish green in Cheilolejeunea), cell wall thickenings (cells usually thin-walled with distinct trigones, and walls usually uniformly thickened in Cheilolejeunea), lobule development (most often fully developed in Cheilolejeunea, often reduced in some species of Lejeunea, underleaf base (basal cells often distinctily larger than adjacent cells in Lejeunea, not so in Cheilolejeunea), gynoecial innovations leaf sequence (always lejeuneoid in Lejeunea, sometimes pycnolejeuneoid in Cheilolejeunea).   Likely confusion between particular species of Cheilolejeunea and Lejeunea is discussed under those species.  One of the North American species belongs to subgenus Cheilolejeunea (C. adnata); the other five belong to subgenus Euosmolejeunea.  Cheilolejeunea is currently placed in subfamily Lejeuneoideae, tribe Lejeuneeae, subtribe Cheilolejeuneinae.  It is the sole member of this subtribe in North America (L. Söderström, et al.  2016).

SELECTED REFERENCES   Cheilolejeunea in Gradstein, S. R. & D. Da Costa.  2003.    Hepaticae and Anthocerotae of Brazil. Mem. New York Bot. Garden 87: 124--129. 1980.  Leucolejeunea in Gradstein, S. R. & D. Da Costa.  2003.  Hepaticae and Anthocerotae of Brazil. Mem. New York Bot. Garden 87: 167.  Evans, A. W.  1908.  Hepaticae of Puerto Rico IX.  Brachiolejeunea, Ptychocoleus, Archilejeunea, Leucolejeunea, and Anoplolejeunea.  Bull. Torrey Bot. Club 35: 155--179.   Cheilolejeunea.  In: R. M. Schuster.  1966--1993.  Hepaticae and Anthocerotae of North America.  New York. Vol. 4, pp. 848--909.  Leucolejeunea.  In: R. M. Schuster.  1966--1993.  Hepaticae and Anthocerotae of North America.  New York. Vol. 4, pp. 814--848.   Schuster, R. M.  2006.  Studies on Lejeuneaceae. V.  On Leucolejeunea and allies.  J. Hattori Bot. Lab. 100:  361--406.  W. Ye & R. Zhu.  Leucolejeunea, a new synonym of Cheilolejeunea (Lejeuneaceae), with special reference to new combinations and nomenclature.  J. Bryol. 32: 279--282.  2010.

1. Underleaves entire.

2.  Lateral leaves strongly convex, basiscopic margin of lobe strongly inrolled, lobule not visible without removing leaf from stem.

3 . Lobule 0.6--0.7 lobe length, tooth rather uniform, strongly falcate, 3--6 cells long, 3--4 cells wide at base, apex acuminate, tooth apex often touching lobule apex, forming a circular sinus ………………………….

……………………............……………4.  Cheilolejeunea conchifolia

3.  Lobule ca. 0.5 lobe length, tooth variable in shape and size, roughly triangular, sometimes acuminate-falcate, 1--3 cells long, 1--3 cells wide at base, sinus irregular to lunulate .………...10.  Cheilolejeunea xanthocarpa

2.  Lateral leaves plane to weakly convex, basiscopic margin not or slightly inrolled, lobule visible without removing it from stem.

4. Lobule 0.3--0.4 lobe length, lobular tooth isodiametric, triangular, composed of 1--2 cells, bluntly rounded to sharply acute, sinus straight to lunulate or slightly sinuous; underleaves distant to contiguous or slightly imbricate, orbicular, upper margin rounded to slightly truncate and retuse, base cuneate …………………….…………..3.  Cheilolejeunea clypeata

4.  Lobule 0.4--0.5 lobe length, lobular tooth variable in shape, broadly to narrowly triangular, straight or falcate, 3--8 cells long, 2--4 cells wide, sinus sinuous and irregular, sometimes with a second distinct to indistinct tooth; underleaves usually imbricate, broadly orbicular to reniform, upper margin rounded to truncate, often retuse, sometimes revolute, base cuneate to cordate…………………………………..…9.  Cheilolejeunea unciloba

1.  Underleaves 2-lobed. 

5.  Lateral leaf lobe margin entire or with rhizoids (on leaves with eventually deciduous lobes); lobule free margin tooth more than 2 times longer than wide, apex acutely pointed; gynoecial innovations usually absent; perianth strongly doriventrally flattened…………………………………  1. Cheilolejeunea adnata

5. Lateral leaf lobes never with rhizoids; lobule free margin tooth quadrate to triangular, apex rounded; gynoecial innovations present; perianth inflated or slightly dorsiventrally flattened.

6.  Plants small (0.2--0.7 mm wide); autoicous.

7.  Lateral leaf lobe apex broadly rounded; leaf cells uniformly thick-walled (distinct trigones absent); light green to grayish green; innovation leaf sequence pycnolejeuneoid; widely distributed in S.E. U.S. ……..…………………..5. Cheilolejeunea. discoidea

7.  Lateral leaf lobe apex narrowly to broadly acute; leaf cells with moderately thick walls and coarse trigones; olive to brownish green; innovation leaf sequence lejeuneoid; distribution limited to Southern Appalachians  ...........................6. Cheilolejeunea evansii

6.  Plants larger (0.6--1 mm wide); dioicous.

8.  Underleaves large (often nearly as large as lateral leaves), contiguous to imbricate, base strongly cordate to auriculate, insertion strongly arched; lateral leaf lobes broadly oblong to orbicular; oil bodies usually 1 per cell ………………..……………………….2. Cheilolejeunea  clausa

8.  Underleaves small to large (not as large as lateral leaves), distant to imbricate, base cuneate to rounded or weakly cordate, insertion straight to shallowly arched; lateral leaf lobe oblong to broadly oblong; oil bodies usually 2--5 per cell.

9.  Underleaves on leading stems orbicular to slightly reniform, imbricate, base rounded to weakly cordate; leaves widely spreading, usually plane; gynoecia with single or one paired innovations, innovations often fertile; microphyllous branches absent; deciduous leaf lobes sometimes present (in C. polyantha var. caduciloba)

…………………………. 5.  Cheilolejeunea polyantha

9.  Underleaves on leading stems obovate (widest above midlength), distant to contiguous, base cuneate to slightly rounded; leaves narrowly to widely spreading; gynoecia with one innovation, innovations usually sterile; microphyllous branches occasionally present; deciduous leaf lobes absent ………….6.  Cheilolejeunea  rigidula

1. Cheilolejeunea adnata (Kunze ex Lehmann) Grolle, J. Bryol. 9: 529.  1977

Jungermannia adnata Kunze ex Lehmann, Nov. Stirp. Pug. 6: 46.  1834; Cheilolejeunea decidua (Spruce) Evans

Plants 0.6--1 mm wide; tightly appressed to substrate, branches with deciduous lobes absent, microphyllous branches absent; light to dark green.  Lateral leaves widely spreading, plane, imbricate; lobe broadly ovate to slightly ovate-falcate, margin entire or with rhizoids (on leaves with eventually deciduous lobes), apex broadly rounded, basiscopic margin plane; cell walls thin, trigones moderate, intermediate thickenings small; oil bodies 2--4.  Lobule ovoid, about 0.25 lobe length, free margin tooth acicular, more than 2 times longer than wide, apex sharply pointed, sinus between tooth and apex contracted, orbicular, apex sharply acute.  Underleaves 2-lobed, smaller than lateral leaves, distant, suborbicular, 1--2 times stem width; lobes 0.5 underleaf length, parallel to divergent, 7--9 cells wide at base, underleaf base cuneate, attachment straight to slightly arched.  Specialized asexual reproduction by deciduous leaf lobes.  Sexual condition dioicous.  Gynoecia restricted to short branches, innovations usually absent, if present, always single and sterile, leaf sequence lejeuneoid; bracts approximately equal in size to lateral leaves, bracteole 2--3 times underleaf size; perianth with 4 keels, dorsiventrally compressed. 

Bark of living trees and sometimes decorticated wood; evergreen forests in the most humid regions of the se Coastal Plain; low elevations; Fla.; s Mexico; West Indies; Central America; South America.

Cheilolejeunea adnata is the easiest to distinguish from the other North American species of Cheilolejeunea.  All plants of C. adnata appear to have deciduous leaf lobes, which can be identified prior to dehiscence by the presence or marginal rhizoids.  The lobule apex also clearly differentiates this species in that the free margin tooth is long and sharply pointed, and the sinus between the tooth and the lobule apex is contracted, forming a circular opening.   Cheilolejeunea adnata might be confused with Rectolejeunea berteroana, which also has rhizoids on the leaf margin and a sharply pointed lobule free margin tooth.  However, R. berteroana has ocelli in the leaf lobe (scattered as well as basal), underleaves with distinctly angled lateral margins, the hyaline papilla is proximal to the lobule free margin  tooth, gynoecial innovations are usually present, and the innovation leaf sequence is pycnolejeuneoid.

2.  Cheilolejeunea clausa (Nees & Montagne) R.  M. Schuster, Hepat. Anthoc. N.  Amer. 4: 863. 1980

Lejeunea clausa Nees & Montagne, Ann. Sci. Nat., Bot., ser. 2, 14: 337.  1840; Euosmolejeunea clausa Evans; E. opaca (Gottsche) Stephani

Plants 0.6--1 mm wide; stems often very long and sparsely branched, loosely interwoven over substrate, branches with deciduous lobes absent, microphyllous branches absent; whitish to dull olive pale grayish green. Lateral leaves narrowly spreading, convex, imbricate; lobe broadly oblong to orbicular, margin often crenulate, apex broadly rounded, basiscopic margin plane; cell walls thin, trigones very large, cordate, intermediate thickenings absent; oil bodies usually 1 per cell.  Lobule ovoid-triangular, 0.2 --0.3 lobe length, free margin tooth bluntly triangular, sinus between tooth and apex straight to weakly lunulate, apex acute to subacute.  Underleaves 2-lobed, as large as lateral leaves, contiguous to imbricate, orbicular to quadrate, 3--5 times stem width; lobes extending 0.3--0.5 underleaf length, parallel to connivent, 6--9 cells wide at base, underleaf base strongly cordate to auriculate, attachment strongly arched.  Specialized asexual reproduction absent.  Sexual condition dioicous.  Gynoecia on short branches, innovations present or occasionally absent, always single, leaf sequence lejeuneoid, always sterile; bracts 15--2 times longer than lateral leaves, bracteole 1--1.25 times underleaf size; perianth with 5 keels, dorsal keel more weakly defined, somewhat dorsiventrally flattened. 

On bark of living trees; confined to low-lying forests, swamps or forests adjoining coastal streams; low elevations; Ala., Fla., Ga., La., Miss., S.C.; Mexico; West Indies; Bermuda; Central America; South America.

When typically developed, Cheilolejeunea clausa is easily distinguished from all other species of Cheilolejeunea by the very long, sparsely branched main stems, convex lateral leaves, and very large, imbricate underleaves.  In some populations, however, the underleaves are smaller and contiguous rather than imbricate.  At this extreme C. clausa may be confused with C. rigidula.  However, the underleaf base in C. clausa is always rounded to cordate (not cuneate as in C. rigidula), and gynoecia are almost always limited to short branches with short, sterile innovations.  The lobule in C. clausa is usually triangular-ovoid, not ovoid as in C. rigidula.  Confusion with C. polyantha is also possible, though less likely; plants of C. polyantha tend to produce strong secondary branches as long as primary branches and grow more tightly appressed to the substrate.  The leaf lobe is more widely spreading in C. polyantha, and gynocial plants of C. polyantha often paired innovations and innovatios in series.  Cheilolejeunea clausa is closely related to C. trifaria, a pantropical species, according to R. M.Schuster (1980). S. Gradstein and D. da Costa (2003) differentiate the species based on sexuality (C. trifaria is monoicous), underleaf shape (wider than long in C. trifaria) and the occasional presence of deciduous leaf lobes in C. trifaria.

3.  Cheilolejeunea clypeata (Schweinitz) W. Ye & R. L. Zhu, J. Bryol. 32: 280, 2010

Jungermannia clypeata Schweinitz, Spec. Fl. Amer. Sept. Crypt. Hepat. P. 12.  1821;

Archilejeunea clypeata (Schweinitz) Schiffner; Leucolejeunea clypeata (Schweinitz) A. Evans

Plants 1.5--2 mm wide; forming appressed mats, branches with deciduous lobes absent, microphyllous branches absent; glaucous or pale grayish green.  Lateral leaves widely spreading, weakly convex, imbricate, lobe orbicular to oblong ovate and slightly falcate, margin entire, apex rounded, plane to slightly deflexed (but not involute), basiscopic margin plane cuneate to rounded; cell walls thin, trigones small or large, triangular to cordate, intermediate thickenings sometimes present; oil bodies 1 or rarely 2.  Lobule visible without removing leaf from stem, ovate-triangular to ovate-oblong, 0.3--0.4 lobe length, apex acute, tooth isodiametric, triangular, composed of 1--2 cells, bluntly rounded to sharply acute, sinus straight to lunulate or slightly sinuous, keel straight to rounded.  Underleaves entire, smaller than lateral leaves, distant to contiguous or slightly imbricate, orbicular, 1--3 times stem width, upper margin rounded to slightly truncate and retuse, underleaf base cuneate, insertion straight to slightly arched.    Gynoecia usually terminal on long branches, occasionally on short branches, innovations usually single or paired, leaf sequence pycnolejeuneoid, sometimes fertile; gynoecial bracts not or slightly larger than lateral leaves, bracteole not or slightly larger than underleaves; perianths keels 4--5, not or slightly flattened.

On bark of living trees, rock walls and boulders; Ala., Ark., Conn., Del., D.C., , Fla., Ga., Ind., Kans., Ky., Mass., Md., Mich., Miss., Mo.,  N.C., N.H., N. J., N.Y., Ohio, Okla., Pa., R.I., S.C., Tex., Tenn., Vt., Va., W. Va. 

Cheilolejeunea clypeata is the most widely distributed species in North America, and is morphologically the most variable of the entire-leaved Cheilolejeuneas.  Plants from different areas or habitats may differ greatly in vigor. R. M. Schuster (1980) related the morphological variations in C. clypeata to geographic regions of the Southeastern U.S.  He described plants of wetter, mountainous regions of the Piedmont as the typical form with small lobules (0.3 lobe length), lobule apices obtuse to rounded, underleaves distant to approximate; plants of the same region but from drier habitats he describe as having suberect to almost squarrose leaves, lobules larger (up to 0.5 lobe length), more convex leaves with a weaker lobule tooth and distant underleaves.  These squarrose-leaved plants might be confused with C. xanthocarpa, although in C. xanthocarpa the lobule is usually longer (0.6--0.7 lobe length) and the free margin is strongly inrolled.  The third form, characteristic of the coastal plain, that has more imbricate underleaves, a lobule up to 0.5 lobe length, lobule tooth cell larger (2-celled).   Such forms might be confused with C. unciloba, which differs nonetheless in the irregular nature of the lobule free margin tooth and the long, sinuous sinus between tooth and lobule apex.   

4.  Cheilolejeunea conchifolia (A. Evans) W. Ye & R.L. Zhu, J. Bryol. 32: 280. 2010  E

Archilejeunea conchifolia A. Evans, Mem. Torrey Bot. Club 8: 128.  1902; Leucolejeunea conchifolia (A. Evans) A. Evans

Plants 0.7--1.5 mm wide; forming appressed mats, branches with deciduous lobes absent, microphyllous branches absent; whitish green to pale yellowish green.  Lateral leaves strongly convex, lobe asymmetrically ovate, apex rounded, basiscopic margin strongly inrolled; cell walls thin, trigones small or large, triangular to cordate, intermediate thickenings sometimes present; oil bodies 1 or rarely 2.  Lobule not visible without removing leaf from stem, narrowly oblong-ovate, 0.6--0.7 lobe length, apex acute, rather uniform, tooth strongly falcate, 3--6 cells long, 3--4 cells wide at base, apex acuminate, tooth apex often touching lobule apex, forming a circular sinus, keel straight to rounded.  Underleaves entire, smaller than lateral leaves, contiguous to imbricate, orbicular to somewhat wider than long, 3--5  times stem width, upper margin truncate, entire to slightly retuse, margin plane, underleaf base cuneate to rounded, insertion straight to slightly arched.   Gynoecia usually terminal on long branches, occasionally on short branches, innovations usually single or paired, leaf sequence pycnolejeuneoid, sometimes fertile; gynoecial bracts not or slightly larger than lateral leaves, bracteole not or slightly larger than underleaves; perianths keels 4--5, not or slightly flattened.

On bark of living trees; Ala., Fla, Ga., La., Miss., N.C., S.C., Tex.,Va.

The strongly convex leaves, the long, narrow lobules and the acuminate, hook-shaped tooth distinguish Cheilolejeunea conchifolia, which is endemic to the southeastern flora region.  The shape of the tooth and of the circular sinus formed between the tooth and lobule apices are quite uniform within the species.  Rarely one encounters plants with a reduced lobule tooth; such plants could be confused with C. xanthocarpa.  Cheilolejeunea conchifolia is sometimes misidentified as C. unciloba, but the nature of the lobule apex and the sinus between tooth and lobe apex should separate these species easily.  Also, C. conchifolia is similar in size to C. clypeata, smaller than either C. unciloba or C. xanthocarpa.

5.  Cheilolejeunea discoidea (Lehmann & Lindenberg) Kachroo & R. M. Schuster, J. Bot. Linn. Soc. 56: 509.  1961.

Jungermannia discoidea Lehmann & Lindenberg, Pug. 6: 47.  1834; Cheilolejeunea myriantha (Nees & Montagne) Schuster; Euosmolejeunea parvula Evans

Plants 0.4--0.7 mm wide, tightly appressed to substrate, light green; branches with deciduous lobes absent, microphyllous branches occasionally present.  Lateral leaves narrowly spreading, plane to convex, contiguous; dorsal lobe broadly ovate to ovate-triangular, margin entire, apex broadly rounded, basiscopic margin plane; cell walls uniformly thick-walled, trigones and intermediate thickenings absent; oil bodies 1--3 per cell. Lobule ovoid, 0.3--0.5 lobe length, free margin tooth quadrate to triangular, apex rounded, sinus between tooth and apex weakly to strongly lunulate, apex acute to attenuate-falcate (curved slightly upward).  Underleaves 2-lobed, smaller than lateral leaves, distant to barely contiguous, broadly ovate to suborbicular, 2--3 times stem width; lobes extending 0.4--0.5 underleaf length, parallel to divergent, 4--6 cells wide at base, underleaf base cuneate, attachment straight to slightly arched.  Specialized asexual reproduction absent.  Sexual condition autoicous.  Gynoecia usually restricted to short branches, innovations present throughout, always single and sterile, leaf sequence pycnolejeuneoid; bracts 1.3--1.5 times longer than lateral leaves, bracteole 3--4 times underleaf size; perianth with 5 keels, slightly dorsiventrally flattened, dorsal keel less defined. 

Bark of living trees; in oak forests, hammock forests and mangrove swamps; low elevations; Ala., Ga, Fla., N.C., S.C; Mexico; West Indies; Bermuda; Central America; South America.

The most distinctive features of C. discoidea are the very small size, the convex, narrowly spreading leaf lobes, the very small trigones, the often numerous perianths (plants autoicous), and the pycnolejeuneoid innovation leaf sequence.  This species could probably only be confused with C. evansii, which is similar in size.  However, C. evansii has acute leaf lobes, more bulging trigones, larger lobules relative to the lateral leaves and a lejeuneoid innovation leaf sequence. 

6.  Cheilolejeunea evansii (M. S. Taylor) R.  M. Schuster, Hepat. Anthoc. N.  Amer. 4: 876. 1980  E

Euosmolejeunea evansii M. S. Taylor, Ann. Bryol. 11: 155.  1938

Plants 0.4--0.7 mm wide, appressed to substrate; branches with deciduous lobes absent, microphyllous branches occasionally present, light green.  Lateral leaves narrowly spreading, plane to slightly convex, contiguous; dorsal lobe broadly ovate to ovate-triangular, margin entire, apex narrowly to broadly acute, basiscopic margin plane; cell walls moderately thick, trigones large, triangular to cordate, intermediate thickenings absent; oil bodies 1--3.  Lobule ca. 0.5 lobe length, free margin tooth isodiametric, rounded, sinus between tooth and apex weakly to strongly lunulate, apex acute to attenuate-falcate (curved slightly upward).  Underleaves 2-lobed, smaller than lateral leaves, distant to barely contiguous, broadly ovate to suborbicular, 2--3 times stem width, lobes extending 0.4--0.5 underleaf length, parallel to divergent, 4--6 cells wide at base, underleaf base cuneate, attachment straight to slightly arched.  Specialized asexual reproduction absent.  Sexual condition autoicous.  Gynoecia on short or long branches, innovations present throughout, always single and sterile, leaf sequence lejeuneoid; bracts 2--2.5 times longer than lateral leaves, bracteole 4--5 times underleaf size; perianth with 5 keels. 

On bark of living trees; deeply shaded ravines near swiftly flowing water, or on wooded slopes of gorges; moderate elevations;  Ala. (Covington, Jackson counties), Ga. (Rabun Co.), N. C. (Jackson, Macon, Transylvania counties), S. C. (Pickens, Oconee counties).

Chilolejeunea evansii is known only from the Blue Ridge Escarpment near the the southern edge of the Blue Ridge Mountains.  Because of its very limited distribution, this species is unlikely to be confused with any other species of Cheilolejeunea. It is most similar in appearance to C. discoidea, as discussed under that species.

7.  Cheilolejeunea polyantha A. Evans, Mem. Torrey Bot. Club 8: 141.  1902 E

Euosmolejeunea polyantha (A. Evans) R. M. Schuster & Hattori

Plants 0.6 --1.0 mm wide, in tightly appressed mats or tufts, green- to yellowish or olive-green, branches with deciduous lobes occasionally present; microphyllous branches absent.  Lateral leaves widely spreading, usually plane, contiguous to densely imbricate; dorsal lobe ovate to orbicular, margin entire to slightly crenulate, apex acutely to broadly rounded, basiscopic margin plane; cell walls moderately thick, trigones small, rarely moderate, triangular, intermediate thickenings usually absent, oil bodies 2--5. Lobule ovoid to ovoid-rectangular, 0.3 --0.4 lobe length, free margin tooth isodiametric, bluntly pointed, sinus between tooth and apex straight to weakly lunulate, apex acute to attenuate-falcate (curved slightly downward).  Underleaves 2-lobed, imbricate, smaller than lateral leaves, orbicular to slightly reniform, 3--4 times stem width; lobes extending 0.5 underleaf length, parallel to divergent, 10--14 cells wide at base, underleaf base rounded to weakly cordate, attachment straight to slightly arched.  Specialized asexual reproduction by deciduous leaf lobes occasionally present.  Sexual condition dioicous.  Gynoecia on short or long branches, innovations present throughout, single or paired, often fertile, leaf sequence lejeuneoid; bracts 1.5--2.6 times longer than lateral leaves, bracteole 1.5--2 times underleaf length; perianth with 4 keels extending 0.5 length, dorsiventrally flattened ventral keels less well defined than lateral keels. 

Varieties 2; restricted to central and southern Florida.

As the name suggests, gynoecial plants of Cheilolejeunea polyantha typically bear many gynoecia, usually arranged in a series of fertile innovations arranged in series (one fertile innovation per gynoecium, subtended by another single fertile innovation) or in parallel (two innovations per gynoecium, each subtended by fertile innovations. The large underleaves that are often wider than long are also diagnostic for this species, however this feature is observable only on mature stems---the underleaves are small and distant on young stems.  Plants with small underleaves (especially sterile ones) may be difficult to distinguish from C. rigidula. However, even when small, the underleaves are almost always clearly orbicular in C. polymorpha (i.e., widest at midleaf), but in C. rigidula are obovate  (widest above midleaf).

1.  Leaves imbricate, convex, lobes not deciduous; underleaves densely imbricate, reniform, slightly wider than long, 1.2 times wider than long, base cordate to auriculate; gynoecia on long leafy shoots with 1(--2) innovations per gynoecia …………………....

…………………………………………….a.  Cheilolejeunea  polyantha var. polyantha

1.  Leaves contiguous, plane, lobes often deciduous; underleaves contiguous, suborbicular, approximately as wide as long, base rounded; gynoecia usually on short branches with single innovations …………b. Cheilolejeunea polyantha var. caduciloba

1a.  Cheilolejeunea polyantha var. polyantha   E

Lateral leaves weakly to strongly imbricate; lobe convex. Underleaves imbricate, orbicular to reniform, usually wider than long, base cordate to auriculate.  Specialized asexual reproduction by deciduous leaves absent. Gynoecia on short or long branches, innovations single or paired, usually fertile.

On bark of living trees and shrubs (trunks and branches); infrequent in moist hammock forests; low elevations; Fla., Ga., La., S.C.

1b.  Cheilolejeunea polyantha Evans var. caduciloba R. M. Schuster, Hepat. Anthoc. N. Amer. 4: 887. 1980  E

Lateral leaves contiguous; lobe plane. Underleaves contiguous, suborbicular, about as wide as long, base rounded.  Specialized asexual reproduction by deciduous leaf lobes. Gynoecia usually on short branches, innovations present throughout, usually single, often fertile.

On bark of living trees, usually near trunk base; open hammock forests; low elevations;.  Fla., Ga, La.

8.  Cheilolejeunea rigidula (Nees ex Montagne) R. M. Schuster, Hepat. Anthoc. N. Amer. 4: 893. 1980

Lejeunea rigidula Nees ex Montagne, Ann. Sci. Nat., Bot., ser. 2, 14: 336.  1840;  Cheilolejeunea duriuscula (Spruce) Schiffner, Eusomolejeunea duriuscula (Spruce) Evans, Euosmolejeunea rigidula (Montagne) Steph; Lejeunea austinii Lindberg, Lejeunea duriuscula Spruce, Lejeunea underwoodii Stephani

Plants 0.6 --1 mm wide, tightly appressed to substrate, olive green, branches with deciduous lobes absent, microphyllous branches occasionally present.  Lateral leaves narrowly to widely spreading, flattened to slightly convex, contiguous to imbricate; lobe ovate to oblong, sometimes slightly falcate, margin entire, apex broadly rounded, basiscopic margin plane; cell walls thin to moderately thick, trigones small to large, triangular to cordate, intermediate thickenings usually absent; oil bodies 2--4.  Lobule ovoid to ovoid-rectangular, 0.2--0.25 lobe length, free margin tooth isodiametric, rounded, sinus between tooth and apex weakly lunulate, apex acute to attenuate.  Underleaves 2-lobed, smaller than lateral leaves, distant to contiguous, obovate, widest above midlength, 2.5--4.0 times stem width; lobes extending 0.3--0.4 underleaf length, parallel to slightly divergent,  6--13 cells wide at base, underleaf base cuneate to slightly rounded, attachment straight to slightly arched.  Specialized asexual reproduction absent.  Sexual condition dioicous.  Gynoecia on short or long branches, innovations present throughout, always single, usually sterile, leaf sequence lejeuneoid; bracts 1--1.5 times longer than lateral leaves, bracteole 1.5--2.0 times underleaf size; perianth with 4--5 keels, dorsal keel less well defined, keels extending 0.3--0.5 perianth length. 

On bark of living leaves, on decorticated wood, rarely on soil; in coastal forests, hammocks, swamps, palmetto woodlands; low elevations; Ala., Fla., Ga., La., Miss., N.C., S.C., Tex.; Mexico; West Indies; Central America; South America; Asia); Africa; Atlantic Islands; Indian Ocean Islands; Pacific Islands; Australia.

Cheilolejeunea rigidula is a very polymorphic species that in extreme phases can resemble C. clausa (large underleaved phase, apparently growing in deep shade) or C. polyantha (plants with paired or fertile innovations).   The most consistent features of this species are the shape of the lateral leaf (always distinctly longer than wide) and the underleaf (obovate, and cuneate to slightly rounded at the base.

9. Cheilolejeunea unciloba (Lindenberg) Malombe, Acta Bot. Hung. 51: 325. 2009

Lejeunea unciloba Lindenberg in C. M. Gottsche, J. B. W. Lindenberg & C. G. D. Nees, Syn. Hepat., 331.  1845; Archilejeunea unciloba Schiffner; Leucolejeunea unciloba (Lindenberg) A. Evans

Plants up to 2 mm wide, forming appressed mats, pale glaucous to grayish green; branches with deciduous lobes absent, microphyllous branches occasionally present.  Lateral leaves plane, lobe oblong-ovate, sometimes slightly falcate, apex rounded, not or very weekly incurved, basiscopic margin plain or only slightly involute, cell walls thin, trigones small or large, triangular to cordate, intermediate thickenings sometimes present; oil bodies 1 or rarely 2.  Lobule visible without removing leaf from stem, rectangular, 0.4--0.5 lobe length, apex acute to acuminate, tooth variable in shape, broadly to narrowly triangular, straight or falcate, 3--8 cells long, 2--4 cells wide, sinus sinuous and irregular, sometimes with a second distinct to indistinct tooth, keel straight to slightly arched or slightly rounded, insertion straight to slightly arched.  Underleaves entire, usually imbricate, broadly orbicular to reniform, 3--5 times stem width, upper margin rounded to truncate, often retuse, sometimes revolute, underleaf base cuneate to cordate.  Gynoecia almost always on short branches, innovations single, leaf sequence pycnolejeuneoid, sometimes fertile; gynoecial bracts not or slightly larger than lateral leaves, bracteole not or slightly larger than underleaves; perianths keels 4--5, not or slightly flattened.

.

On bark of living trees, rock walls and boulders; Ala., Ark., Del., Fla., Ga., Ky., La., Md., Miss., N.C., R.I., S.C., Tenn., Tex., Va., W. Va.; Mexico; West Indies; Bermuda; Central America; South America; Africa.

Cheilolejeunea unciloba is the largest species in the genus, although the size range overlaps with all the other species.  The most robust forms have very widely spreading leaves, and a long free margin tooth.  Weak plants (and smaller fertile stems) may have a weakly developed lobular tooth, reminiscent of Cheilolejeunea clypeata.  Cheilolejeunea unciloba is usually larger than C. clypeata, the lobule is longer relative to the leaf lobe, the lobule tooth is usually multi-celled, and is separated from the lobule apex by an elongated, sinuous sinus, unlike C. clypeata.  

10. Cheilolejeunea xanthocarpa (Lehmann & Lindenberg) Malombe, Acta Bot. Hung. 51: 326. 2009

Jungermannia xanthocarpa Lehmann & Lindenberg in Lehmann, Nov. Stirp. Pug. 5: 8.  1833; Archilejeunea xanthocarpa Schiffner; Cheilolejeunea xanthocarpa (Lehmann & Lindenberg) A. Evans

Plants 1--1.5 mm wide, forming appressed mats, pale glaucous green; branches with deciduous lobes absent, microphyllous branches occasionally present.  Lateral leaves strongly convex when wet or dry, lobe (when flattened) broadly ovate to oblong-ovate, apex and basiscopic margin strongly inrolled, cell walls thin, trigones small or large, triangular to cordate, intermediate thickenings sometimes present; oil bodies 1 or rarely 2.  Lobule not visible without removing leaf from stem, due to inrolling, but when flattened is ovoid to oblong, ca. 0.5 lobe length, apex visible without removal of leaf from stem, acuminate, tooth variable in size and shape, roughly triangular, sometimes acuminate-falcate, 1--3 cells long, 1--3 cells wide at base, sinus lunulate, keel straight, continuous with inrolled leaf margin.  Underleaves entire, strongly imbricate, broadly orbicular to reniform, 3--5 times stem width, upper margin rounded or truncate, sometimes slightly recurved, but not retuse, underleaf base rounded to subcordate, insertion straight to slightly arched. Gynoecia on short or long branches, innovations single, leaf sequence pycnolejeuneoid, sometimes fertile; gynoecial bracts not or slightly larger than lateral leaves, bracteole not or slightly larger than underleaves; perianths keels 4--5, not or slightly flattened.

On bark of living trees; Fla., Miss.; Mexico; West Indies; Bermuda; Central America; South America; Asia; Africa; Atlantic Islands; Indian Ocean Islands; Pacific Islands; Australia.

When typically developed, Cheilolejeunea xanthocarpa is quite distinctive because of the leaf orientation. The leaves are leaves strongly convex, with the lobule keel continuous with this revolute border.  This is the least common species of Cheilolejeunea in North America, although it is the most widely distributed species of the genus.

OTHER REFERENCES   Schuster, R. M.  1963.  An annotated synopsis of the genera and subgenera of Lejeuneaceae.  Nova Hedwigia Beih. 9: 1--203.   Schuster, R. M.  1984.  Evolution, Phylogeny and Classification of the Hepaticae.  In: R. M. Schuster, ed.  1984.  New Manual of Bryology.  Vol. 2, pp. 892--1070.  Nichinan, Japan.

5.  COLOLEJEUNEA  (Spruce) Schiffner in Engler & Prantl, Nat. Pflanzenfam. 1(3): 117.  1893 *  [Greek kolos, mutilated, alluding to absence of underleaves), and Lejeunea, a related genus]

Lejeunea subg. Cololejeunea Spruce, Trans. & Proc. Bot. Soc. Edinburgh 15: 291. 1884; Aphanolejeunea A. Evans; Leptocolea (Spruce) A. Evans

Plants up to 1.5 mm wide; all branches tightly appressed to substrate; pure green, whitish or yellow green, sometimes brownish with age.  Branches Aphanolejeunea-type (non-collared) Lejeunea-type (collared).  Stems with 5--6 epidermal surrounding 1 inner cell, epidermal cells not or only slightly larger than inner cells.    Lateral leaf insertion u-shaped, with usually 5 or fewer leaf cells attached to stem; leaves plane when dry or moistened, distant to imbricate; lobe lanceolate to ovate or obovate; cells of leaf midportion isodiametric, cell wall middle lamella colorless, trigones small, intermediate thickenings usually absent; oil bodies 2--15 per cell, oblong to ellipsoid, small to large, segmented, granulose or botryoidal; ocelli absent.  Lobule fully formed or reduced, saccate lobules ovoid, free margin inrolled for up to 0.75 to entire length, usually with two marginal teeth: a weakly to strongly differentiated 1--4 cells long apical tooth, (i.e., located closest to the apex of the lobule) that is separated on its proximal side (i.e., the side toward the lobule base) by a slit-like or U- sinus from a triangular, preapical tooth, hyaline papilla in most of our species on the inner surface of the lobule at the base of the apical tooth; stylus (i.e., a linear to lanceolate projection at the lobule base) consisting of 1--many cells sometimes present.  Underleaves absent, but often with rhizoid bundles at their place.  Specialized asexual reproduction by gemmae produced from dorsal surface of leaf cells.  Sexual condition autoicous (sometimes paroicous).  Androecia on short or long branches, sometimes subtending gynoecia.  Gynoecial innovations present or absent, single or paired; bracts in one pair, similar in size to lateral leaves, margin entire, bract keel rounded, not winged; perianth obovoid to obpyriform, inflated,0--5-keeled, keels when present forming longitudinal folds that extend 0.3--0-.5 perianth length.

Species approximately 380 (11 in the flora): North America, Mexico, West Indies, Bermuda, Central America, South America, Eurasia, Africa, Atlantic Islands (including Macaronesia), Indian Ocean Islands, Pacific Islands (including Hawaii and New Zealand), Australia.

Cololejeunea is easily distinguished from all other North American genera of Lejeuneaceae by the small size of the plants and the absence of underleaves. A. W. Evans (1911) and R. M. Schuster (1980) recognized Aphanolejeunea as distinct from Cololejeunea, based on differences in branch type (Lejeunea-type in Cololejeunea, Aphanolejeunea-type in Aphanolejeunea), gemmae characters (shape, point of origin, presence of adhesive cells) and lateral leaf lobe development (uniform or dimorphic).  However, the lack of consistency in these characters in species outside North America, as well as the nesting of Aphanolejeunea within Cololejeunea in a major phylogenetic reconstruction of the family based on molecular characters (R. Wilson et al, 2007) have led specialists in the group (e.g., T. Pócs in Gradstein & Ilkiu-Borges, 2009, T. Pócs & Bernecker, 2009) to synonymize Aphanolejeunea. Cololejeunea is currently placed in subtribe Cololejeuneinae of tribe Lejeuneaceae of subfamily Lejeuneoideae.  There are 10 genera in this subtribe, of which Diplasiolejeunea is the only other genus that occurs in North America (Söderström, L., et al.  2016). 

SELECTED REFERENCES   Evans, A. W.  Hepaticae of Puerto Rico. X .  Cololejeunea, Leptocolea and Aphanolejeunea.  Bull. Torrey Bot. Club 38: 215--286.  1911.  Pócs, T.   Aphanolejeunea, Cololejeunea in Gradstein, S. R. & D. Da Costa.  2003.  Hepaticae and Anthocerotae of Brazil. Mem. New York Bot. Garden 87:130--135. Pócs, T. & A. Bernecker.  2009. Overview of Aphanolejeunea (Jungermanniopsida) after 25 years.  Polish J. Bot. 54: 1--11.   Schuster, R. M.  1955.  Notes on Nearctic Hepaticae.  III.  Paradoxae:  Cololejeunea, Section Minutissimae.  J. Elisha Mitchell Sci. Soc. 71: 281--247.  Schuster, R. M.  1980.  Cololejeunea, Aphanolejeunea.  In: R. M. Schuster.  1966--1993.  Hepaticae and Anthocerotae of North America.  New York. Vol. 4, pp. 1230--1314.

1.  Plants less than 0.5 mm wide; vegetative branches non-collared (Aphanolejeunea-type); leaves on a given stem strongly dissimilar in size, small leaves usually lacking a lobule.

2.  Plants 0.2 mm wide or less; gemmae growing into a long, linear bi-seriate thallus before producing new vegetative shoots. [TB1] .…. 8.  Cololejeunea minuscula

2.  Plants up to 0. 5 mm wide; gemmae growing directly into new vegetative shoots (no bi-seriate thallus stage).

3. Apical tooth of lobule free margin 2-celled, separated from preapical tooth by a broad u- or v- shaped sinus, oil bodies 2--6 per cell.

4.  Dorsal lobe narrowly ovate, ca. 1.5--2 times longer than wide, apex subacute to acute; dorsal surface of each lobe cell with a large, conical papilla with a rounded, thick-walled apex; perianth at maturity with 5 weak keels (sometimes barely discernible…..

……………………………….3.  Cololejeunea clavatopapillata

4.  Dorsal lobe lanceolate to ovate-lanceolate, 2--3 times longer than wide, apex acute to acuminate;  dorsal surface of each lobe cell with a small conical papilla that is thin-walled at apex; perianth at maturity with 5 sharp keels……………6.  Cololejeunea diaphana

3. Apical tooth of lobule free margin 1 or 2-celled, separated from preapical tooth by a very narrow slit-like sinus; oil bodies 4--15 per cell.

5.  Lateral leaf lobe up to 2 times longer than wide, apex narrowly to broadly acute, oil bodies 4--9 per cell, composed of minute globules; lobule apical tooth 1 or usually 2-celled, falcate; mature perianths lacking keels…………….....12.  Cololejeunea sintenisii 

5.  Lateral leaf  lobe 2.5--3 times longer than wide, apex narrowly acute to acuminate, oil bodies 4--12, homogeneous, apical tooth 1-celled, straight or weakly falcate;  mature perianth with distinct

keels ................................................ 5.  Cololejeunea cornutissima

1.  Plants usually 0.5--1.5 mm wide; vegetative branches collared cells (Lejeunea-type); on a given stem uniform in size, with lobe and lobule present.

6.  Leaf cells without a papilla on the dorsal surface of each leaf cell.

7. Lobule always reduced, apical tooth 2--5 cells long, preapical tooth absent.….………………………..…………….11.  Cololejeunea setiloba

7. Lobules fully formed or reduced, apical tooth 2 cells long, preapical tooth present.

8.  Lateral leaf lobe broadly ovate to orbicular, apex broadly rounded; saccate lobule up to 0.9 lobe length, perianth terete             ….……………………………………9.  Cololejeunea minutissima

8.  Lateral leaf lobe narrowly ovate; apex acutely rounded, saccate lobule up to 0.50 lobe length, perianth dorsiventrally compressed.

9.  Lateral leaf lobes on mature stems with finger-like hyaline cells projecting from the apex, sometimes also with several rows of finger-like hyaline cells along upper lobe margin; lobule up to 0.5 lobe length; perianth  keels smooth

...…………………………….2.  Cololejeunea cardiocarpa

9.  Lateral leaf lobes without finger-like hyaline cells projecting from the apex or along the upper lobe margin; lobules up to 0.4 lobe length; gemmae 16-celled; perianth keels crenulate  to irregularly dentate……………………… .……………………………..13. Cololejeunea subcristata

6.  Leaf cells with large papillae.

10.  Stylus inconspicuous or absent, if present, consisting of 1--2 thin-walled cells at point of attachment of lobule to stem.

11.  Plants up to 0.9 mm wide; lateral leaf lobes oblong to obovate, slightly falcate, apex broadly rounded; papilla apex rounded; lobules uniformly saccate, apical tooth 2-celled, preapical tooth single-celled, narrowly triangular and falcate (British Columbia) ……………………….………………………………………………….7.  Cololejeunea macounii

11.  Plants up to 0.5 mm wide; lateral leaf lobes ovate to ovate lanceolate, not falcate, apex acutely pointed; papilla apex acutely pointed; lobules usually reduced, apical tooth single-celled, preapical tooth multicellular, broadly triangular, linear  (Southeastern U.S.)……………………………..………………………………………………4. Cololejeunea contractiloba

10.  Stylus conspicuous, forming a multi-celled projection (1--12 cells long, 1--2  cells wide) at point of attachment of lobule to stem.

12 .  Lateral leaf lobe apex sharply acute; lobule usually reduced, lobule cells papillose; stylus 1--9 cells long by 1--2 cells wide, stylus cells sometimes papillose; gemmae absent; known only from the southeastern U.S.  …………………………..….……..……….10.  Cololejeunea ornata

12 .  Lateral leaf lobe apex acutely rounded; lobule uniformly saccate,  lobule cells lacking papillae; stylus 5--12 cells long, 1 cell wide, stylus cells not papillose, gemmae present; known from northeastern  North America……………………………………1. Cololejeunea biddlecomiae

1.      Cololejeunea biddlecomiae (Austin ex Pearson) A. Evans, Mem. Torrey Bot. Club 8: 168.  1902

Lejeunea biddlecomiae Austin ex Pearson, List Canadian Hepat., 5.  1890; Lejeunea calcarea Sullivant; L. echinata Austin

Plants up to 0.75 mm wide.  Branches Lejeunea-type  Lateral leaves  on a given stem uniform in size, with lobe and lobule present; lobe ovate, 1.3--2  times longer than wide, apex acutely rounded, margin serrulate; dorsal surface of each lobe cell elevated into a prominent, conical, thick-walled papilla; oil bodies 4--12  per cell, composed of small globules.  Lobule uniformly saccate, broadly ovoid, up to 0.5 lobe length, cells convex but not papillose; apical tooth of free margin 2--4-celled, triangular to acicular, preapical tooth triangular, smaller than apical tooth, sinus between preapical and apical tooth u- or v-shaped; stylus conspicuous, ciliate, 5--12 cells long, 1 cell wide, stylus cells not papillose.  Specialized asexual reproduction by gemmae produced from dorsal surface of interior leaf lobe cells composed of 26--32 cells. Sexual condition autoicous.  Perianth inflated, keels 5, forming sharp longitudinal folds that extend 0.5 perianth length, keels and surface of perianth between keels papillose in upper 0.75 of perianth length.

On bark of living trees or rock (usually calcareous).  N.B., N.S., Ont., Que.; Ark., Conn., D.C., Ga., Ind., Ill., Iowa, Kans., Ky., Maine, Mass., Mich., Miss., Minn., Mo., N.C., N.H., N.J., N.Y., Ohio, Okla., Pa., S.C., Tenn., Va., Vt., W. Va., Wis.; Europe;

Cololejeunea biddlecomiae is the most widespread and abundant species of Cololejeunea in North America. The ovate lateral leaf lobe with rounded apex and sharp conical papillae, the usually uniformly saccate lobule and conspicuous multicellular stylus are the most distinctive features. The species shows very little variation from population to population.  It  superficially resembles C. contractiloba and C. ornata.  Cololejeunea contractiloba is similar in gemma type, leaf cell papillae, and the faintly segmented oil bodies.  However, C. contractiloba often has reduced lobules, and lacks a distinct stylus at the ventral base of the lobule. C. ornata has a prominent stylus, as does C. biddlecomiae, but is smaller, has sharply acute leaf lobes, often has reduced lobules and  lacks gemmae.

2.      Cololejeunea cardiocarpa (Montagne) A. Evans, Mem. Torrey Bot. Club 8: 172. 1902

Lejeunea cardiocarpa Montagne in Sagra, Hist. Phys. Cuba, Bot., Pl. Cell.), 476. 1842; Cololejeunea jooriana (Austin) A. Evans

Plants up to 1.2 mm wide.  Branches Lejeunea-type.  Lateral leaves on a given stem uniform in size, with lobe and lobule present; lobe narrowly ovate, ca. 2  times longer than wide, apex acutely rounded to pointed, margin mostly entire, but with 2--10 hyaline, finger-like cells projecting from the apex, sometimes also with several rows of finger-like hyaline cells along upper lobe margin; cells not papillose; oil bodies 3--7 per cell, composed of large globules.  Lobule usually saccate, broadly ovoid, up to 0.5 lobe length, cells not papillose; apical tooth of free margin 2-celled, acicular, preapical tooth triangular, smaller or as large as apical tooth, sinus between preapical tooth and apical tooth u- or v-shaped; stylus absent or existing as a single thin-walled cell, not papillose.  Specialized asexual reproduction by gemmae produced from ventral surface of interior leaf lobe cells, composed of 25--28 cells. Sexual condition autoicous (sometimes paroicous).  Perianth dorsiventrally flattened, keels 5, forming sharp longitudinal folds that extend 0.5--0.7 perianth length, keels and surface between keels smooth.

On bark of living trees (twigs, branches and trunks), living leaves; hammock forests; low elevations; Ala., Fla., La., Miss., N.C., S.C., Va.; Mexico; West Indies; Bermuda; Central America; South America; Eurasia; Africa; Atlantic Islands; Indian Ocean Islands; Australia.

When normally developed, the hyaline, finger-like cells at the lobe apex are diagnostic for Cololejeunea cardiocarpa. However, sometimes these are poorly developed or lacking, and if care is not taken when removing the plant from the substrate, the hyaline cells may be severed from the leaf margin.  Very well developed plants will have a distinct hyaline border on upper lobe margin (i.e., toward the shoot apex).  Another source of variation within the species is antheridial position.  These are sometimes produced in morphologically distinct androecial bracts on separate branches, but sometimes are produced in the axils of typically-appearing lateral leaves that subtend a gynoecium.  Among North American species, C. cardiocarpa is most likely to be confused with C. subcristata, from which it is differentiated in lead 9 of the species key.

3.  Cololejeunea clavatopapillata Stephani,  Hedwigia 34: 246.  1895

Aphanolejeunea tuberculata (A. Evans) R. M. Schuster; Cololejeunea tuberculata A. Evans

Plants up to 0.4 mm wide.  Branches  Aphanolejeunea-type.  Lateral leaves on a given stem uniform in size, with lobe and lobule present; lobe narrowly ovate, ca. 1.5--2 times longer than wide, apex subacute to acute, margin sharply dentate; dorsal surface of each lobe cell with a large, conical papilla with a rounded, thick-walled apex; oil bodies 2--4  per cell, composed of minute globules (barely discernible at 1000X).  Lobule saccate or most often reduced, when saccate ovoid, up to 0.5 lobe length, cells papillose, apical tooth of free margin 2-celled, acicular, pre-apical tooth triangular, smaller than apical tooth, sinus between preapical tooth and apical tooth, wide u- or v- shaped, reduced lobules rectangular, apical tooth as in saccate lobule, but preapical tooth reduced; stylus absent or existing as a single thin-walled cell, not papillose.  Specialized asexual reproduction by gemmae produced from marginal lobe cells, composed of 16--18 cells, growing directly into new vegetative shoots. Sexual condition autoicous.  Perianth inflated, keels 5 in the juvenile form (still enclosed in bracts) but at maturity lacking keels or with weak keels, entire perianth surface papillose in upper 0.6--0.6 of perianth.

On living leaves of Trichomanes.  Fla.; West Indies; South America; Africa.

The most distinctive features of C. clavatopapillata are the large knob-like papillae on all lobe and lobule cells, the keel-less or weakly keeled perianth and the non-collared (Aphanolejeunea-type) vegetative branches.  C. clavatopapillata is most similar to C. ornata in papilla structure and distribution on the plant (basically on all leaf surfaces), as well as leaf and bract shape.  Cololejeunea ornata, however, produces Lejeunea-type branches, has a very distinct stylus at the lobule base, lacks gemmae, and mature perianths have five distinct keels. Cololejeunea sintenisii also has keel-less perianths, but has ovate-lanceolate to broadly lanceolate leaves, an elongate, falcate lobule apical tooth that is separated from a the pre-apical tooth by a narrow slit-like sinus.

4.  Cololejeunea contractiloba A. Evans, Amer. J. Bot. 5: 131.  1918

Plants up to 0.5 mm wide.  Branches Lejeunea- or Aphanolejeunea-type.  Lateral leaves on a given stem uniform in size, with lobe and lobule present;  lobe ovate to ovate-lanceolate,  not falcate, ca. 2 times longer than wide, apex acutely pointed (terminated by 1--2 cells), margin sharply crenulate to serrulate; dorsal surface of each lobe cell with an acutely pointed papilla with a thickened cell wall at apex; oil bodies 3--7  per cell, composed of small or large globules. Lobule rarely saccate, usually reduced, occasionally vestigial, when saccate ovoid to broadly oblong, 0.5--0.6 lobe length, cells not papillose, apical tooth of free margin 1-celled, weakly to strongly differentiated, acicular to triangular, preapical tooth multicellular, broadly triangular, not falcate, equal in size or larger than apical tooth, sinus between preapical tooth and apical tooth variable, u- or wide v- shaped; stylus absent or existing as a single thin-walled cell, not papillose.  Specialized asexual reproduction by gemmae produced from ventral surface of interior leaf lobe cells, composed of 1--20 cells. Sexual condition autoicous (sometimes paroicous).  Perianth dorsiventrally flattened, keels 5, forming sharp longitudinal folds that extend 0.5 perianth length, keels and surface between keels papillose.

On bark of living trees (twigs, shrubs and trunks), rarely decorticated wood or limestone rock faces; dense hammock forests or along riverbanks and in flood zones low elevations; Ala., Fla., Ga., Miss., La.; s Mexico; South America.

The most distinctive features of C. contractiloba are the presence to two vegetative branch types (Lejeunea- and Aphanolejeunea-type), the prominent conical papillae, the lobule preapical tooth that is larger than the apical tooth, and the absence of a stylus. 

The leaf shape and strongly developed conical papillae suggest C. biddlecomiae, as described under that species.  Cololejeunea ornata also has similar papillae, but has a conspicuous stylus and lacks gemmae.

5. Colojeunea cornutissima (R. M. Schuster) Pócs, Polish J. Bot. 54: 4.  2009  E

Aphanolejeunea cornutissima R. M. Schuster, Bryologist 59: 217.  1956; A. evansii R. M. Schuster, hom. illeg. non A. evansii Herzog

Plants up to 0.25 mm wide.  Branches  Aphanolejeunea-type.  Lateral leaves on a given stem strongly dissimilar in size, small leaves lacking a lobule; lobes of lobulate leaves narrowly ovate to lanceolate, 2.5--3 times longer than wide, apex narrowly acute to acuminate, sometimes deflexed, lobes of leaves with reduced or absent lobules ovate to lanceolate, apex acute, margin of both lobe types sharply crenulate to serrulate; dorsal surface of each lobe cell with a small, broadly conical papilla; oil bodies 4--12  per cell, homogeneous.  Lobule saccate or reduced, sometimes completely absent, when saccate ovoid to oblong, 0.4--0.5 lobe length, cells not papillose, apical tooth of free margin 1-celled, bluntly pointed, straight or weakly falcate, preapical tooth triangular, equal in size to apical tooth, sinus between preapical tooth and apical tooth narrow, slit-like; stylus absent or existing as a single thin-walled cell, not papillose.  Specialized asexual reproduction by gemmae produced from marginal leaf lobe cells, composed of 16 cells.  Sexual condition autoicous.  Perianth inflated, keels 5, forming sharply angled longitudinal folds that extend 0.5--0.7 perianth length, keel papillose, surfaces between keels smooth.

On bark of living trees and decaying wood, occasionally on rock in limestone areas.  Fla.

The combination of Aphanolejeunea-type branches, the single celled, bluntly pointed, slightly falcate apical tooth separated from the preapical tooth by a slit-like sinus, and the perianth form (5 sharply angled, denticulate keels) will differentiate the endemic Cololejeunea cornutissima from all others in the genus.  The most similar species is C. sintenisii, which has a 2-celled apical tooth and a perianth with keels weak or lacking.

6.  Cololejeunea diaphana A. Evans, Bull. Torrey Bot. Club 32: 184.  1905

Aphanolejeunea diaphana (A. Evans) R. M. Schuster hom. illeg. non A. diaphana Herzog; Cololejeunea subdiaphana Jovet-Ast

Plants up to 0.5 mm wide.  Branches  Aphanolejeunea-type  Lateral leaves on a given stem more or less uniform in size, with lobe and lobule present;  lobe lanceolate to ovate-lanceolate,  2--3 times longer than wide, apex acute to acuminate, margin crenulate; dorsal surface of each lobe cell with a small conical papilla that is thin-walled at apex; oil bodies 2--6  per cell,  composed of small globules. Lobule saccate or reduced, when saccate ovoid, 0.4--0.5 lobe length, cells not papillose, apical tooth of free margin 2-celled, acicular, preapical tooth triangular, much smaller than apical tooth, sinus between preapical tooth and apical tooth u-or v-shaped; stylus absent or existing as a single thin-walled cell, not papillose.  Specialized asexual reproduction by gemmae produced from marginal or internal leaf lobe cells, composed of 19--22 cells.   Sexual condition autoicous.  Perianth dorsiventrally flattened, keels 5, forming longitudinal folds that extend 0.5--0.7 perianth length, keels papillose, surfaces between keels smooth.

On bark and leaves of living trees, in very humid sites only.  Fla; West Indies (Guadeloupe, Puerto Rico); South America (Brazil, Venezuela); Asia; Africa.

R. M. Schuster (1956) recognized Cololejeunea diaphana var. cristulata in addition to the typical variety.  I agree with T. Pócs (2009) that recognition of this variety is not warranted.   Plants of C. diaphana are indeed somewhat variable among populations in the features used by Schuster to circumscribe the variety (e.g., more prominent papillae, gemmae with 15- 16 cells, as opposed to 20--22 cells), but I found it impossible to consistently differentiate specimens based on these characters.  In leaf shape, C. diaphana is similar to C. ephemeroides, from which it is most easily distinguished by the structure of the teeth on the lobule free margin.  Cololejeunea diaphana is similar to C. sintenisii in the elongate leaf lobe, but C. sintenisii has a hook-shaped apical tooth that is sharply pointed and is separated from the preapical tooth by a narrow slit.

7. Cololejeunea macounii (Spruce ex Underwood) A. Evans, Mem. Torrey Bot. Club 8: 171.  1902

Lejeunea macounii Spruce ex Underwood, Bull. Torrey Bot. Club 17: 259.  1890

Plants up to 0.9 mm wide.  Branches Lejeunea-type.  Lateral leaves on a given stem uniform in size, with lobe and lobule present; lobe oblong to obovate, slightly falcate, 1.5--2 times longer than wide, apex broadly rounded, margin sharply crenulate to serrulate; dorsal surface of each lobe cell with a rounded papilla, cell wall strongly thickened at papilla apex; oil bodies unknown. Lobule uniformly saccate, ovoid, approximately 0.5--0.7 lobe length, cells not papillose; apical tooth of free margin 2-celled, linear, preapical tooth narrowly triangular and falcate, apex sharply pointed, sinus between preapical tooth and apical tooth u- or v-shaped; stylus inconspicuous, composed of 1--2 thin-walled cells, not papillose.  Specialized asexual reproduction by gemmae unknown.  Sexual condition unknown, hypothesized to be autoicous by R. M. Schuster 1955).  Perianth dorsiventrally flattened, keels 5, forming sharp longitudinal folds that extend 0.5 perianth length, keels and surfaces between keels papillate.

On bark of living trees, decorticated wood or rock; B.C.; Asia.

Cololejeunea macounii is one of only two species that occur on the west coast of North America (the other is Lejeunea alaskana). Cololejeunea macounii is known only from the mainland of British Columbia and Moresby Island of the Queen Charlotte Islands in North America, but is also known in Japan, Korea China and Taiwan.  It is apparently most closely related to C. denticulata of Japan.  Because of the strongly disjunct distribution from other species of Cololejeunea, it is highly unlikely that it would be confused with other species.  However, in addition to distribution, the broadly rounded dorsal lobe apices, the rounded, thick-walled papillae and cordate trigones serve to distinguish the species.

8. Cololejeunea minuscula Pócs, Polish J. Bot. 54: 7.  2009  E

Aphanolejeunea minuta R. M. Schuster, Hep. Anthoc. N. Amer. 4: 1390, fig. 774.  1980

Plants extremely small, up to 0.2 mm wide. Branches Aphanolejeunea-type.  Lateral leaves on a given stem strongly dissimilar in size, small leaves (which predominate) lacking a lobule; lobes of elobulate leaves linear to linear-lanceolate, 5--8 cells long by 2--4 cells wide (2 times longer than wide), apex acutely pointed to acuminate, lobes of lobulate leaves ovate, apex narrowly rounded to acute, margin entire to weakly crenulate; dorsal surfaces of some lobe cells gibbous to weakly papillose; oil bodies 6--12 per cell, homogeneous.  Lobule usually reduced to a single cell or absent; saccate lobule spherical to ovoid, 0.6--0.9 lobule length, cells not or weakly papillose apical tooth of free margin 1--2 celled, acicular, preapical tooth absent, stylus absent.  Specialized asexual reproduction by gemmae produced from marginal leaf lobe cells, composed of 10--16 cells, growing into a long, 2-seriate thallus before producing new vegetative shoots. Sexual condition probably dioicous.    Perianths unknown.     

On stems and leaf bases of Sabal palmetto, known only from the type locality in Highlands County, Fla.

According to R. M. Schuster (1980), Cololejeunea minuscula is the smallest hepatic in North America.  The species is still known only from the type locality, although it is likely more widespread but is overlooked because of its small size.  The size, the highly reduced nature of the lateral leaves and the thalloid post-dehiscence stage gemmae are the most distinctive features of the species.  Cololejeunea sintenisii is almost as small, but has larger leaves that are distinctly papillose, and lacks the thalloid gemma phase.

9.  Cololejeunea minutissima (Smith in Sowerby) Schiffner in A. Engler & K. Prantl, Hepat. (Engl.-Prantl), 122.  1893

Jungermannia minutissima Smith in Sowerby, Engl. Bot., 1633.  1806

Plants up to 0.5 mm wide.  Branches Lejeunea-type.  Lateral leaves on a given stem strongly dissimilar in size, size, shape and orientation (see subspecies below); lobe broadly ovate to orbicular, 1--1.4 times longer than wide, apex broadly rounded, margin crenulate; dorsal surface of leaf cells gibbous but not papillose; oil bodies 1--8 per cell,  composed of large globules.  Lobule saccate or explanate, saccate lobules broadly ovoid, up to 0.9 lobe length, cells not papillose, apical tooth of free margin 2-celled, acicular, preapical tooth triangular, smaller than apical tooth, sinus between preapical tooth and apical tooth u- or broad v-shaped; stylus absent or present as a single thin-walled cell, not papillose.  Specialized asexual reproduction by gemmae produced from interior or marginal leaf lobe cells, composed of 14--29 cells.  Sexual condition autoicous.  Perianth inflated, keels 5, forming sharp longitudinal folds that extend approximately 0.5 perianth length, keels and perianth surface between keels smooth.

Subspecies 2.  It is extremely difficult to separate the two subspecies consistently because most populations have a mixture of lobulate and elobulate leaves, because many specimens lack gemmae.  It is tempting to recognize only one polymorphic subspecies.  However, since the species has a worldwide distribution and because the extremes are so distinct, I maintain the two subspecies, pending a re-evaluation of the species throughout its range.

1.  Lobule usually fully formed, 0.8--0.9 lobe length, free margin tooth 2-celled; lobe suborbicular; gemmae composed of 26--48 cells; oil bodies small, 3--6 per cell

1a. Cololejeunea minutissima subsp. minutissima

1.  Lobule usually reduced to a narrow rectangular fold, keel between lobe and lobule weak, 0.6--0.8 lobe length, no distinct free margin tooth; lobe ovate; gemmae composed of 4--16 cells; oil bodies large, usually 1--2 per cell

1b. Cololejeunea minutissima subsp. myriocarpa

1a. Cololejeunea minutissima subsp. minutissima

Lateral leaf lobes plane to convex; oil bodies 2--8 per cell.  Lobule appressed to lobe, saccate.  Specialized asexual reproduction by gemmae composed of 26--48 cells. 

On bark of living trees; tolerant bright sunlight, salt spray; low elevations; Ala., Fla., Miss., La., N.C., S.C., Tenn., Tex., Va.; Mexico; West Indies; Bermuda; Central America; South America; Eurasia; Africa; Atlantic Islands; Indian Ocean Islands; Pacific Islands; Australia.

The large size of the lobule relative to the lobe, and the absence of papillate leaf cells separate C. minutissima subsp. minutissima from all other North American species of Cololejeunea.  However, many plants exhibit at least some explanate or squarrose leaves that are identical to those of C. minutissima var. myriocarpa.  As noted by R. M. Schuster (1980) plants from the northern and western edges of the range have fewer explanate leaves than those from the southern extremes.  Perhaps the species most likely to be confused with it is Microlejeunea ulicina, which has a similar leaf shape and lobe-to-lobule size ratio.  However, M. ulicina has underleaves (which are small and could be overlooked in casual inspection), usually one or more ocelli, and no preapical tooth on the lobule free margin.

1b. Cololejeunea minutissima subsp. myriocarpa (Nees & Montagne) R. M. Schuster, J. Elisha Mitchell Sci. Soc. 71: 232.  1955

Lejeunea myriocarpa Nees & Montagne in Ramon del la Sagra,Hist. Phys. Cuba, Bot.,  473.  1842;  Cololejeunea myriocarpa A. Evans

Lateral leaf lobes squarrose; oil bodies large, 1--2 (rarely 3--4) per cell.  Lobule usually plane, always reduced, not appressed against lobe but separated from it by a crease, lobule without a distinct tooth.  Specialized asexual reproduction by gemmae composed of 14--29 cells.   

On bark of living trees (trunks and exposed roots), decorticated wood, living leaves; low elevations; Fla.; c Mexico, West Indies.

The most distinctive feature of Cololejeunea minutissima var. myriocarpa is the conspicuous flap-like lobule that usually has no marginal teeth and with a free margin that is not at all inrolled.  There is an intergradation between this type of lobule and that of the typical variety, however.

10.  Cololejeunea ornata A. Evans, Bryologist 41: 73.  1938

Plants up to 0.5 mm wide.  Branches Lejeunea-type.  Lateral leaves on a given stem uniform in size, with lobe and lobule present; lobe ovate, 1.5--2 times longer than wide, apex sharply acute, often deflexed, margin sharply crenulate to serrulate; dorsal surface of each lobe cell with a conical papilla, thick-walled at apex; oil bodies 3--6 per cell, composed of fine segments (barely distinct at 1000\x).  Lobule rarely saccate, usually reduced, saccate lobule ovoid to broadly oblong, 0.5--0.8 lobe length, cells papillose, apical tooth of free margin 1--2-celled, acicular, preapical tooth similar in size and shape to apical tooth, both teeth variable in size and shape among lobules on the same stem, preapical tooth usually smaller than apical tooth, sinus between preapical and apical tooth usually broadly u-shaped, reduced lobules rectangular, flattened, with a well-defined 1--2 celled marginal tooth, stylus well-developed, variable in size and shape, filamentous (1--9 cells long by 1--2 cell wide); stylus cells sometimes papillose.  Specialized asexual reproduction by gemmae absent.  Sexual condition autoicous.  Perianth inflated keels 5, forming weak longitudinal folds that extend 0.3--0.5 of perianth length, perianth keels and surface between keels papillose.  

On calcareous rock; low elevations; Fla., S.C., Tenn.; Japan.

Cololejeunea ornata is distinctive in its multicellular, sometimes even papillose stylus, the presence of sharply pointed papillae on leaves, lobules, styli and perianths, and the terete, weekly keeled perianth.  Cololejeunea biddlecomiae is similar in stylus elaboration, but lacks papillae on lobule and produces gemmae.

11.  Cololejeunea setiloba A. Evans, Bryologist 16: 51.  1913  E

Plants up to 0.8 mm wide.  Branches Lejeunea-type.  Lateral leaves on a given stem uniform in size, with lobe and lobule present; lobe ovate, 1.5--2 times longer than wide, apex acutely (rarely broadly) rounded, margin entire; dorsal surface of each lobe cell weakly convex but not papillose, oil bodies 2--4 per cell, composed of large globules.  Lobule always reduced, narrowly rectangular, 0.3--0.4 lobe length, cells not papillose, apical tooth of free margin 2--5 celled, acicular, tipped by the hyaline papilla, preapical tooth absent; stylus absent or existing as a single thin-walled cell, not papillose.  Specialized asexual reproduction by gemmae produced from ventral surface of interior leaf lobe cells, composed of 16 cells.  Sexual condition autoicous or paroicous.   Perianth inflated, keels 5, forming longitudinal folds that extend 0.5--0.7 perianth length, keels and surface between keels smooth,keels sometimes crenulate due to strongly convex cells.

On bark of living trees (trunks and twigs), decorticated wood; low elevations; Ala., Fla, La.

The lobule consisting of a narrow rectangular flap topped by an elongate apical tooth is diagnostic for Cololejeunea setiloba, an endemic.  The lobule in C. setiloba is reminiscent of that in Lejeunea pililoba, but the two species are easily distinguished because L. pililoba is larger and has 2-lobed underleaves.  The reduced lobules and non-papillose leaf cells are features shared in common by this species with C. minutissima var. myriocarpa, however the species differ in leaf lobe shape (almost orbicular in C. minustissima var. myriocarpa) and lobule tooth (1 blunt cell on reduced lobules in C. minutissima var. myriocarpa).

12.  Cololejeunea sintenisii (Steph.) Pócs, Crypt. Bryol. 29: 235.  2008

Lejeunea sintenisii Steph., Hedwigia 27: 291. 1888; Aphanolejeunea ephemeroides R. M. Schuster

Plants up to 0.35 mm wide.  Branches Aphanolejeunea-type. Lateral leaves on a given stem strongly dissimilar in size, small leaves usually lacking a lobule; lobes of lobulate leaves ovate-lanceolate to lanceolate, up to 2 times longer than wide, apex narrowly to broadly acute to acuminate, leaves with reduced or absent lobules also ovate-lanceolate but much smaller, 4--8 cells long and 3--8 cells wide, margin crenulate to denticulate; dorsal leaf cell surfaces with small conical papillae per cell; oil bodies 4--9 per cell, composed of minute globules.  Lobule saccate or reduced, when saccate ovoid, 0.4--0.75 lobe length, cells papillose, apical tooth of free margin 1 or usually 2-celled, falcate,  preapical tooth triangular, smaller than apical tooth, sinus between preapical tooth and apical tooth narrow, slit-like; stylus absent or existing as a single thin-walled cell, not papillose. Specialized asexual reproduction by gemmae produced from marginal or internal leaf lobe cells near the leaf apex, composed of 16 cells.  Sexual condition autoicous.  Perianth inflated, without keels, perianth surface papillose in upper half.

On bark of living trees (trunks and exposed roots).  Fla.; West Indies, Central America; South America; Asia; Africa; Atlantic Islands; Australia.

The diagnostic features for C. sintenisii are the elongated, sharply pointed and hook-shaped apical tooth and the eplicate perianths. Poorly developed, sterile plants could be confused with C. cornutissima, which normally can be easily differentiated as described in key couplet 5.

13.  Cololejeunea subcristata A. Evans, Bryologist 20: 24.  1917  E

Plants up to 0.85 mm wide.  Branches Lejeunea-type.  Lateral leaves  on a given stem uniform in size, with lobe and lobule present; lobe narrowly ovate, ca. 1.5 times longer than wide, apex acutely rounded, margin mostly entire; cells not papillose; oil bodies 3--10 per cell, composed of large globules. Lobule usually saccate, ovoid, 0.3--0.4 lobe length, cells not papillose, apical tooth of free margin 2-celled, acicular to slightly falcate, preapical tooth triangular, smaller than apical tooth, sinus between preapical tooth and apical tooth  u- or v-shaped; stylus absent or existing as a single thin-walled cell, not papillose.  Specialized asexual reproduction by gemmae produced from ventral surface of interior leaf lobe cells, composed of 16 cells.  Sexual condition autoicous.  Perianth not or barely dorsiventrally flattened, keels 5, forming longitudinal folds that extend 0.5--0.7 perianth length, keels crenulate to irregularly dentate surface between keels smooth.

On bark of living trees and living leaves, rare; low elevations; Fla.

Among the regional species of Cololejeunea lacking papillae, Cololejeunea subcristata differs from C. minutissma in leaf shape (ovate in C. subcristata, broadly ovate to orbicular in C. minutissima) and lobule size (0.3--0.4 lobe length in C. subcristata, 0.9 lobe length in C. minutissima).  Cololejeunea subcristata differs  from C. setiloba in the consistent development of saccate lobules, and from C. cardiocarpa in the absence of a hyaline leaf margin.  However, as described under that species, C. cardiocarpa can be difficult to distinguish from C. subcristata. Molecular study and/or morphological study of a broader range of specimens of C. subcristata may reveal that these two species should be treated as one. 

6. DIPLASIOLEJEUNEA  (Spruce) Schiffner in A. Engler & K. Prantl, Hepat. (Engl.-Prantl) 1(3): 121.  1893 *  [Greek diplasio, doubled, and Lejeunea, a related genus]

Plants ca. 1-- 2 mm wide; tightly appressed to substrate; pale to yellow green, sometimes brownish with age.  Branches Lejeunea-type.  Stems with 7 epidermal and 3 inner cells, epidermal cells not or slightly larger.  Lateral leaf insertion u-shaped, with usually 5 or fewer leaf cells attached to stem; leaves widely spreading when dry, plane to convex, imbricate, lobe ovate to suborbicular; leaf cells isodiametric, cell wall middle lamella colorless, trigones small, weak intermediate thickenings sometimes present; oil bodies 3--8 per cell, fusiform to elliptical, botryoidal; ocelli present, scattered in leaf lobe.  Lobule always fully formed, ovate to oblong, 0.5--0.7 lobe length, free margin inrolled for 0.5 --0.9 lobule length, with 2 strongly differentiated teeth, hyaline papilla on the inner surface of the lobule at the base of the free margin tooth; stylus absent.  Underleaves produced in a 1:1 ratio with lateral leaves, inserted across 2 stem cells, imbricate, 2-lobed, obdeltate, 4--6 times stem width; lobes divergent, lateral margins entire, base cuneate, cells of underleaf base uniform in size. Specialized asexual reproduction by gemmae produced from dorsal surface of interior leaf cells. Sexual condition autoicous.  Androecia on short branches, bracteoles present throughout (in 1:1 ratio with bracts).  Gynoecial innovations present, single; bracts in one pair, as large as lateral leaves, keel sharply folded, with a narrow wing; perianth oblong to obclavate, 5-keeled, keels extending 0.3--0.5 perianth length. 

Species ca. 70 (1 in the flora): North America, Mexico, West Indies, Bermuda, Central America, South America, Africa, Atlantic Islands (including Macaronesia), Indian Ocean Islands, Pacific Islands (including Hawaii and New Zealand), Australia.

Diplasiolejeunea is distinguished from other North American Lejeuneaceae by the presence of underleaves produced in a 1:1 ratio with lateral leaves (rather than a 1:2 ratio as in other genera with underleaves).  The doubling of the number of underleaves results from the sequence of divisions of the tetrahedral apical cell of the shoot.  R. M. Schuster (1980) described the sequence in Diplasiolejeunea as “pendulum type” because there is one ventral cell division after each lateral cell division.  Because Cololejeunea shares a segmentation pattern (though without underleaves) and both have a narrow, u-shaped leave insertion, Schuster (1980) placed Diplasiolejeunea in the Cololejeuneoideae. Molecular characters reinforce that these genera are closely related.  Diplasiolejeunea is currently placed in subfamily Lejeuneoideae, tribe Lejeuneeae, subtribe Cololejeuneinae with Cololejeunea and eight extra-North American genera (L. Söderström et al.  2016).

SELECTED REFERENCES   Evans, A.W.  Hepaticae of Puerto Rico. XI.  Diplasiolejeunea.  Bull. Torrey Bot. Club 39: 205--225.  1912.  Schäfer-Verwimp, A.   Diplasiolejeunea  in Gradstein, S. R. & D. Da Costa.  2003.    Hepaticae and Anthocerotae of Brazil. Mem. New York Bot. Garden 87: 140--144. Reyes, D.  1982.  El género Diplasiolejeunea en Cuba.  Acta Bot. Acad. Scient. Hung. 28: 145--180. Schuster, R. M.  1980.  Diplasiolejeunea.  In: R. M. Schuster.  1966--1993.  Hepaticae and Anthocerotae of North America.  New York. Vol. 4, pp. 1220--230.

1. Diplasiolejeunea rudolphiana Stephani, Hedwigia 35: 79.  1896

Plants 1--1.8 mm wide.  Lateral leaf lobe broadly ovate, 1.0 --1.5 x 1mm, margin entire, chlorophyllous (i.e., not hyaline) apex broadly rounded, acroscopic base cordate, basiscopic lobe base rounded, somewhat incurved.  Lobule proximal tooth irregular, poorly defined; distal tooth strongly differentiated, ciliate, 6--12 cells long; sinus between tooth and apex strongly rounded, apex acute to attenuate.  Underleaf lobes extending 0.5 underleaf length; lobes lanceolate, 5--8 cells wide at base, apex acute; margin entire, base cuneate. Gynoecial bracteole 2-lobed for 0.25--0.3 bracteole length, lobes parallel; perianths exerted for at least 0.5 perianth length.

On bark of branches and twigs of living trees and shrubs; hammock forests; low elevations; Fla.; Mexico; West Indies; Bermuda; Central America; South America; Africa; Atlantic Islands (including Macaronesia); Indian Ocean Islands; Pacific Islands (including Hawaii and New Zealand); Australia.

On superficial examination (dorsal surface only) D. rudolphiana might be mistaken for a species of Leucolejeunea, which is similar in size and color.

7. DREPANOLEJEUNEA  (Spruce) Schiffner, Hepat. (Engl.-Prantl) 1: 126.  1893 *  [Greek drepanon, a sickle, and Lejeunea, a related genus]

Lejeunea subg. Drepanolejeunea Spruce, Trans. & Proc. Bot. Soc. Edinburgh 15: 186. 1884

Plants up to 0.7 mm wide; forming tightly appressed mats, microphyllous branches sometimes present; light to yellowish green. Stems with 7 epidermal surrounding 3 inner cells, epidermal cells not or slightly larger.   Branches Lejeunea-type.  Lateral leaf insertion J-shaped, dorsal insertion longer than ventral, more than 5 leaf cells attached to stem; spreading when dry, plane to convex when moistened, distant to contiguous; lobe ovate-falcate, apex attenuate; cells of leaf midportion isodiametric to slightly longer than wide, cell wall middle lamella colorless, trigones small to moderate, triangular, intermediate thickenings rarely present; oil bodies usually 2--5 per cell, small to medium-sized, oblong to broadly elliptical, segmented or granular; ocelli present, 1--3 in leaf midportion.  Lobule always fully formed, flask-shaped, 0.4--0.8 lobe length, convex proximally, plane distally, inrolled for 0.5--0.9 length, 1 single-celled marginal tooth, sharply pointed, hook-shaped, hyaline papilla at proximal base of tooth; stylus absent.  Underleaves produced in a 1:2 ratio with lateral leaves, inserted across 2 stem cells, distant, 2-lobed, obdeltate, not or barely wider than stem; lobes divergent, filiform; lateral margins entire, base cuneate, cells of underleaf base uniform in size.  Specialized asexual reproduction by reduced, deciduous branches.  Sexual condition usually dioicous.  Androecia on short or long branches, bracteoles at base only.  Gynoecial on short or long branches, innovations present, single, usually sterile, leaf sequence pycnolejeuneoid; bracts in one pair, somewhat larger than lateral leaves, margin entire, keel sharply folded, not winged; perianth obovoid, not or slightly dorsiventrally flattened, keels 5, forming sharp, spinose-dentate shoulder-like crests. 

Species ca. 120 (2 in the flora): North America, Mexico, West Indies, Bermuda, Central America, South America, Africa, Atlantic Islands (including Macaronesia), Indian Ocean Islands, Pacific Islands (including Hawaii and New Zealand), Australia.

R. M. Schuster (1990) considered Harpalejeunea and Leptolejeunea to be the genera most closely related to Drepanolejeunea, based on underleaf lobe orientation and the presence of ocelli (in some species).  Drepanolejeunea is currently placed in subfamily Lejeuneoideae, tribe Lejeuneeae, subtribe Drepanolejeuneinae.  This is the sole North American genus in this subtribe (L. Söderström et al.  2016).

SELECTED REFERENCE   Schuster, R. M.  1980.  Drepanolejeunea.  In: R. M. Schuster.  1966--1993.  Hepaticae and Anthocerotae of North America.  New York. Vol. 4, pp. 1192--1206.  

1. Leaves slightly falcate, basiscopic lobe base straight to slightly arched; lobule 0.5--0.6 lobe length; free margin tooth 1--2 celled, strongly hook-shaped, ocelli 2--5 per leaf; coastal plain ……………………………………………1.  Drepanolejeunea  sabaliana

1.  Leaves strongly falcate, basiscopic lobe base strongly arched; lobule 0.6--0.8 lobe length; free margin  tooth 1 celled,  straight or slightly curved; ocelli 1--2 per leaf; montane ………………………………………………2.  Drepanolejeunea appalachiana

1.  Drepanolejeunea sabaliana R. M. Schuster, J. Elisha Mitchell Sci. Soc. 83: 215.  1967  E

Plants 0.3--0.7 mm wide.  Lateral leaf lobe slightly falcate, apex long acuminate, tapering to a point that is a single cell wide and 1--3 cells long, acroscopic base straight to cuneate, basiscopic base straight to slightly arched; ocelli forming a broken line in the leaf midportion, 3--5 per leaf, often with 1--2 basal ocelli as well.  Lobule 0.5--0.6 lobe length, free margin tooth 1--2 celled, strongly hook-shaped, sharply pointed. Underleaf lobes suberect to weakly divergent. Androecia and Gynoecia not known. 

On bark of living trees, shrubs and lianas on decorticatd wood, occasionally on living leaves, vertical rock faces or boulders; deep shaded forests, swamps or along streams; low elevations; Fla., Miss.

The most distinctive features of the endemic Drepanolejeunea sabaliana are the small size, acuminate leaf lobes with prominent ocelli, and the underleaf lobes with uniseriate, slightly divergent underleaf lobes.  It is likely to be confused only with D. appalachiana, from which it is distinguished in the key. 

2.  Drepanolejeunea appalachiana R. M. Schuster, J. Elisha Mitchell Sci. Soc. 83: 219, fig. 76.  1967

Plants 0.25--0.5 mm wide.  Lateral leaf lobe strongly falcate, apex short acuminate, tapering to a single cell, acroscopic base straight to slightly sinuous, basiscopic base strongly arched; ocelli 1--2 at leaf base.  Lobule 0.6--0.8 lobe length, free margin tooth 1 celled, straight or slightly curved, keel crenulate in outline due to inflated cells. Underleaf lobes strongly divergent. Androecia unknown.  Gynoecial bract lobe 1--1.5 times leaf length, apex acuminate, margin dentate, margin crenulate to denticulate, bracteole sinus extending 0.25 bracteole length, lobes erect, acute to acuminate, dentate; perianth keels coarsely spinose. 

On bark of living trees, rarely on decorticated wood or living leaves; dense forests in sites near flowing water; low elevations; Ga., N.C., S.C., Tenn., Va.; West Indies (Puerto Rico).

The most distinctive features of Drepanolejeunea appalachiana are the small plant size, acuminate leaf lobes with prominent ocelli, and the underleaf lobes with uniseriate, slightly divergent underleaf lobes.  It is likely to be confused only with D. sabaliana, from which it is distinguished in the key. 

8.  FRULLANOIDES Raddi, Critt. Bras., 13.  1822 *  [similar to Frullania]

Brachiolejeunea subg. Plicolejeunea R. M. Schuster

Plants up to 1.5 mm wide; stems tightly appressed mats; dark brown to inky black.  Branches Lejeunea or Frullania-type.  Stems composed of 12--14 epidermal surrounding 22--36 inner cells, epidermal cells larger.  Lateral leaf insertion J-shaped, dorsal insertion longer than ventral, more than 5 leaf cells attached to stem; leaves convolute when dry, squarrose to widely spreading when moistened, imbricate; lobe ovate-falcate to oblong-falcate; cells of midportion longer than wide, cell wall middle lamella colorless, trigones large and cordate, intermediate thickenings absent; oil bodies 15--30 per cell, small, fusiform to ellipsoidal, surface smooth; ocelli absent.   Lobule always fully formed, ovate-triangular, 0.3--0.6 lobe length, inflated along keel but sharply flattened above, free margin plane throughout, with 4--6,  marginal teeth, 1--4-celled, bluntly pointed, hyaline papilla on the inner surface of the lobule at the base of first or second tooth; stylus absent.  Underleaves produced in a 1:2 ratio with lateral leaves, inserted across 4--6 stem cells, 3--4 times stem width, imbricate, entire, orbicular to obdeltate, upper margin truncate to broadly rounded, sometimes shallowly retuse, lateral margins plane, base cordate to auriculate, cells of underleaf base uniform in size.  Specialized asexual reproduction absent.  Sexual condition autoicous or dioicous.  Androecia on terminal or intercalary long branches, bracteoles present throughout.  Gynoecial innovations present, often paired, sometimes fertile, leaf sequence pycnolejeuneoid; bracts in one pair, larger than lateral leaves, keel sharply folded, with an auriculate wing near the base; perianth oblong to obovoid, inflated, keels 5--10, forming longitudinal folds extending entire perianth length.

Species 8 (2 in the flora): North America, Mexico, West Indies, Bermuda, Central America, South America.

Frullanoides can be separated from other North American genera of Lejeuneaceae by the dark secondary pigmentation, the multiple lobule teeth, usually paired and often fertile gynoecial innovations, and pluriplicate perianths.  R. M. Schuster (1980) did not recognize Frullanoides, and instead placed the two North American species in Brachiolejeunea subg. Plicolejeunea.  However, M. van Slageren (1985) considered Brachiolejeunea subg. Plicolejeunea to be sufficiently distinct from the other subgenera of Brachiolejeunea to recognize at the generic level, based on stem anatomy, pigmentation, sporophyte and sporeling characters.  He reinstated Frullanoides for this group.  Frullanoides is currently placed in subfamily Ptychanthoideae, with other regiona genera Acrolejeunea, Caudalejeunea, Lopholejeunea and Mastigolejeunea (Söderström, L., et al.  2016).

SELECTED REFERENCES   Evans, A. W.  1908.  Hepaticae of Puerto Rico IX.  Brachiolejeunea, Ptychocoleus, Archilejeunea, Leucolejeunea, and Anoplolejeunea.  Bull. Torrey Bot. Club  35: 155--179.   Gradstein, S. R.  1994.  Frullanioides.  In:  Lejeuneaceae:   Ptychantheae, Brachiolejeuneae.  Flora Neotropica Monograph 62: 130--142.   Schuster, R. M.  1980.  Brachiolejeunea.  In: R. M. Schuster.  1966--1993.  Hepaticae and Anthocerotae of North America.  New York. Vol. 4, pp. 757--774.   van Slageren, M. W.  1985.   A taxonomic monograph of the genera Brachiolejeunea and Frullanoides (Hepaticae), with a SEM analysis of the sporophyte in the Ptychanthoideae.  Utrecht.

1.  Dioicous; free margin teeth 3--6, each tooth 1--3-cells long, 1 cell wide at base, lobule teeth unevenly spaced along margin, first tooth situated close to lobule apex (within 5--7 cells of attachment to lobe), hyaline papilla at base of second tooth  …………….……...

………………………………………………………………….1.  Frullanoides corticalis

1.  Autoicous (rarely paroicous); free margin teeth 5--6, each tooth 1--5 cells long, 1--2 cells wide at base, lobule teeth evenly spaced along margin, first tooth not situated close to lobule apex (separated from point of attachment to lobe by more than 7 cells), hyaline papilla at base of first tooth ……………………………......2.  Frullanoides bahamensis

1.  Frullanoides bahamensis (A. Evans) van Slageren, Meded. Bot. Mus. Herb. Rijks Univ. Utrecht 544: 81.  1985 

Brachiolejeunea bahamensis A. Evans, Bull. Torrey Bot. Club 35: 383.  1908

Plants ca. 1 mm wide.  Branches Lejeunea-type. Lateral leaf lobe ovate to ovate-oblong, apex broadly to acutely rounded, acroscopic base cordate to slightly auriculate.  Lobule free margin with 5--6 teeth, each tooth 1--5 cells long, 1--2 cells wide at base, lobule teeth evenly spaced along margin, first tooth (i.e., tooth closest to lobule apex)  separated from point of attachment to lobe by more than 7 cells, hyaline papilla at base of first  tooth (i.e., tooth closest to lobule apex); lobule apex attenuate, often falcate, sinus between distalmost tooth and lobule apex elongate.  Underleaf base cordate to weakly auriculate. Sexual condition autoicous (rarely paroicous).  Gynoecial bract apex acutely pointed; lobule rectangular; bracteole base cuneate; perianth exerted for 0.20--0.25 perianth length, with 9--10 keels.

On bark of living trees, on rock; well-developed or degraded forests, salt or fresh water marshes; low elevations; Fla; West Indies.

Frullanoides bahamensis is likely to be confused only with F. corticalis, from which it differs in the arrangement of teeth on the lobule, as described in the species key.  It might also be confused with Acrolejeunea heterophylla, as discussed under that species.  The dark brown to black pigmentation is a trait shared with species of Lopholejeunea, Mastigolejeunea and Neurolejeunea. However, F. bahamensis has multiple lobule teeth (lobule tooth is single in Lopholejeunea, Mastigolejeunea and Neurolejeunea) paired innovations (innovations lacking in Lopholejeunea), and pluriplicate perianths (3-keeled in Mastigolejeunea, 2-keeled and compressed in Neurolejeunea).

2.     Frullanoides corticalis (Lehmann & Lindenberg) van Slageren, Meded. Bot. Mus. Herb. Rijks Univ. Utrecht 544: 84.  1985

Jungermannia corticalis Lehmann & Lindenberg in Lehmann, Nov. Min. Cogn. Stirp. Pug. 4: 50.  1832; Brachiolejeunea corticalis (Lehmann & Lindenberg) Schiffner

Plants up to 1.5 mm wide.  Branches usually Lejeunea-type, sometimes Frullania-type.  Lateral leaf lobe ovate, apex broadly rounded, acroscopic base cordate.  Lobule free margin with 3--6 teeth, each tooth 1--3-cells long, 1 cell wide at base, lobule teeth unevenly spaced along margin, first (most proximal) tooth situated close to lobule apex (within 5--7 cells of attachment to lobe), hyaline papilla at base of second tooth (i.e., tooth next to proximal most tooth); lobule apex acute, sinus between distalmost tooth and lobule apex short (4--6 cells), straight or slightly sinuous.  Underleaf base rounded to cordate. Sexual condition dioicous.  Gynoecial bract lobe apex acutely to obtusely rounded, lobule narrowly ligulate, bracteole base auriculate; perianth exerted for 0.2--0.33 perianth length, with 5--10 keels.

On bark of living trees (on rock outside of the flora area); hammock forests, mangrove swamps; low elevations; Fla; West Indies; South America.

Frullanoides corticalis is likely to be confused only with F. bahamensis, from which it is most easily distinguished by the arrangement of teeth on the lobule, as described the species key.  Differentiation of F. corticalis from other Lejeuneaceae with undivided underleaves is the same as described for F. bahamensis.

5. HARPALEJEUNEA  (Spruce) Schiffner in A. Engler & K. Prantl, Hepat. (Engl.-Prantl) 126.  1893 * [English harp, alluding to the shape of the underleaves, and Lejeunea, a related genus]

Lejeunea subg. Harpalejeunea Spruce, Trans. & Proc. Bot. Soc. Edinburgh 15: 164. 1884

Plants up to 1 mm wide; forming tightly appressed mats; pale to grayish green.  Stems with 7 epidermal surrounding 3--10 inner cells, epidermal cells not or slightly larger.  Branches Lejeunea-type.  Lateral leaf insertion J-shaped, dorsal insertion longer than ventral, more than 5 leaf cells attached to stem; leaves convolute to deflexed when dry, plane to convex when moistened, contiguous to imbricate; lobe ovate-falcate, apex acute; cells of leaf midportion isodiametric to slightly longer than wide, cell wall middle lamella colorless, trigones small to moderate, triangular to cordate, intermediate thickenings sometimes present; oil bodies usually 1--6 per cell, small, oblong to elliptical, segmented to botryoidal; ocelli present, 1--4, basal.  Lobule always fully formed, flask-shaped, 0.4--0.6 lobe length, convex proximally, plane distally, inrolled for 0.5--0.9 length, 1 single-celled marginal tooth, sharply pointed, straight or curved, hyaline papilla at proximal base of tooth; stylus absent.  Underleaves produced in a 1:2 ratio with lateral leaves, inserted across 2 stem cells, distant, 2-lobed, obdeltate, not or barely wider than stem; lobes parallel to divergent, filiform, lateral margins entire, base cuneate to rounded, cells of underleaf base uniform in size.  Specialized asexual reproduction usually absent (if present, by reduced, deciduous branches).  Sexual condition usually dioicous.  Androecia on short or long branches, bracteoles at base only.  Gynoecia on short or long branches, innovations present, single or paired, leaf sequence lejeuneoid, usually sterile; bracts in one pair, not or slightly larger than lateral leaves, margin entire, keel sharply folded, often with a narrow wing; bracts in one pair, not or slightly larger than lateral leaves, margin entire; perianth obovate to obclavate, not or slightly dorsiventrally flattened, keels 5, forming sharp longitudinal folds that extend 0.3--0.5 perianth length. 

Species 30 (2 in the flora): North America, Mexico, West Indies, Bermuda, Central America, South America, Africa, Atlantic Islands (including Macaronesia), Indian Ocean Islands, Pacific Islands (including Hawaii and New Zealand), Australia.

R. M. Schuster (1990) considered Drepanolejeunea and Leptolejeunea to be the genera most closely related to Harpalejeunea, based on underleaf lobe orientation and the presence of ocelli (in some species).  Harpalejeunea is currently placed in subfamily Lejeuneoideae, tribe Lejeuneeae, subtribe Lejeuneinae.  Other regional genera in the subtribe include Lejeunea and Microlejeunea (L. Söderström et al.  2016).

SELECTED REFERENCES   Grolle, R. & M. Reiner-Drehwald.  1999.  Review of the genus Harpalejeunea (Lejeuneaceae) including the description of H. grandis sp. nov. from páramos of Colombia.  J. Bryol. 21: 31--45.  Schuster, R. M.  1980.  Harpalejeunea.  In: R. M. Schuster.  1966--1993.  Hepaticae and Anthocerotae of North America.  New York. Vol. 4, pp. 1174--1192.  

1.    Lateral leaf lobe apex acute to apiculate, usually terminated by a single cell, lobe 1.5 --2 times as long as broad; trigones small, triangular to slightly bulging, intermediate thickenings usually absent; perianth keels smooth...1.  Harpalejeunea ovata ssp. integra

1.  Lateral leaf lobe apex acuminate, usually terminated by a tooth of 2--4 cells, lobe ca. 2 times as long as broad; trigones large and bulging, intermediate thickenings usually present; perianth keels denticulate near perianth apex…………………...2.  Harpalejeunea stricta

1.  Harpalejeunea ovata (Hooker) Schiffner ssp. integra R. M. Schuster, J. Elisha Mitchell Sci. Soc. 83: 199.  1967

Plants 0.4--0.6 mm wide.  Lateral leaf lobe 1.5 --2 times as long as broad, apex acute to apiculate, usually terminated by a single cell, acroscopic base cuneate to rounded, basiscopic base cordate to auriculate; trigones small, triangular to slightly bulging, intermediate thickenings usually absent.   Lobule ovate, 0.3--0.5 lobe length. Underleaves obcordate to obdeltate; lobes 4--6 (--8) cells broad at base. Gynoecial bract lobe ovate to orbicular, apex narrowly to broadly acute, bracteole oblong quadrate to oblong, lobes rounded; perianth keels smooth.

On bark of living trees, decorticated wood, vertical rock faces or boulders; deep shaded forests, swamps or along streams; low elevations; Ala., Fla, Ga., Ky., Miss., N.C.,  S.C., Tenn, Va., W.Va; West Indies; Europe.

According to R. M. Schuster (1980) Harpalejeunea ovata subsp. integra differs from the typical variety (not known from North America) in the unlobed (or emarginated) gynoecial bracteole, smaller size, and somewhat larger ventral stem epidermal cells.  Harpalejeunea ovata subsp. integra is most likely to be confused with H. stricta, from which it is differentiated in the key. Harpalejeunea ovata subsp. integra might also be confused with Drepanolejeunea appalachiana, from which it differs in underleaf lobe shape. The underleaf lobe is 4--8 cells wide with rounded apex in H. ovata subsp. integra but 1--2 cells wide and with an acutely pointed apex in D. appalachiana.

2.  Harpalejeunea stricta (Lindenberg & Gottsche) Stephani, Hedwigia 27: 291.  1888.

Lejeunea stricta Lindenberg & Gottsche, Syn. Hepat., 756.  1847

Plants 0.5--1 mm wide.  Lateral leaf lobe falcate, ca. 2 times as long as broad, apex acuminate, usually terminated by a tooth 2--4 cells long, acroscopic base straight to cuneate, basiscopic base strongly auriculate; trigones of leaf cells large and  bulging, intermediate thickenings usually present.  Lobule ovate, 0.4--0.6 lobe length. Underleaves broadly obtrapezoidal; lobes 4--5 cells broad at base. Gynoecial bract lobe ovate, apex acute to apiculate or acuminate, bracteole oblong quadrate to oblong, lobes acutely pointed; perianth keels denticulate near apex.

On bark of living trees, decorticated wood, vertical rock faces or boulders; in deep shaded forests, swamps or along streams; low elevations; Ala., Fla., Ga., Ky., Miss., N.C., S.C., Va., W.Va.; Mexico; West Indies; Europe.

As suggested by R. M. Schuster (1980) specimens from North America show features of both H. ovata and H. stricta, indicating that H. stricta should perhaps be considered a synonym of H. ovata.  However, since both of these species have ranges far beyond North America, a more extensive survey of specimens throughout the range of both species warranted.

10. LEJEUNEA  Libert, Ann. Gén. Sci. Phys. 6: 372.  1820 *  [For Alexandre Louis Simon Lejeune (1779--1858) of Vervier, Belgium]

Plants up to 1.6 mm wide; forming loosely or tightly appressed mats; pale yellowish to pure green.   Branches Lejeunea-type.  Stems with 7--12 epidermal cells surrounding 3--35 inner cells, epidermal cells distinctly larger than inner cells.  Lateral leaf insertion J-shaped, dorsal insertion longer than ventral, more than 5 leaf cells attached to stem; leaves spreading when dry, plane to convex when moistened, distant, contiguous or imbricate; lobe basically ovate, 1--1.5 times longer than wide, apex bluntly to acutely rounded, rarely pointed to apiculate, base at attachment to lobule straight to rounded, sometimes cordate; cells of leaf midportion isodiametric, cell wall middle lamella colorless,, trigones sometimes absent, usually small to large, triangular to cordate, intermediate thickenings sometimes present, usually small; oil bodies usually 2--50 per cell, small to large, spherical to elliptical or oblong, homogeneous or composed of small to large globules; ocelli absent.  Lobule saccate or reduced to a small flap or a stylus-like appendage, when saccate ovate to oblong, 0.1--0.5 lobe length, convex proximally, plane distally, inrolled for 0.75--0.9 length (flattened throughout or nearly so in L. cavifolia and L. sharpii), with a single-celled marginal tooth, bluntly to sharply pointed, isodiametric to elongate, reduced lobules in some species with a multicellular tooth (1--3 cells long in L. monimiae, 2--6 cells wide, 8--16 cells long in L. spiniloba and L. trinitensis), hyaline papilla at proximal base of tooth; stylus absent.  Underleaves produced in a 1:2 ratio with lateral leaves, inserted across 2 stem cells, 2-lobed, ovate to orbicular, 1--4 times stem width; lobes parallel to connivent, triangular; lateral margins entire or with a single tooth, base lunulate to cuneate to cordate, flanking cells of underleaf base (i.e., the basalmost marginal cell on each side of stem) often larger and more distinctly rounded in outline than other underleaf basal cells.  Specialized asexual reproduction absent or if present, by dehiscent leaves or branches.  Sexual condition autoicous or dioicous.  Androecia on long or short branches, bracteoles usually at base only (except in L. alaskana).  Gynoecia on short or long branches, innovations usually present, single or paired, innovation leaf sequence lejeuneoid sometimes fertile; bracts in one pair, similar in size or larger than lateral leaves, margin entire, keel rounded to sharply folded, rarely winged; perianth obovoid to obcordate, inflated or dorsiventrally flattened, keels 4--5, keels forming longitudinal folds that extend 0.3--0.5 perianth length, rarely forming ‘shoulders’ that extend above perianth apex, all keels equally developed, or lateral and ventral keels more often strongly developed than dorsal keels, smooth or crenulate (denticulate in L. bermudiana).

Species ca. 380  (22 in the flora): North America, Mexico, West Indies, Bermuda, Central America, South America, Eurasia, Africa, Atlantic Islands (including Macaronesia), Indian Ocean Islands, Pacific Islands (including Hawaii and New Zealand), Australia.

Schuster (1980) used a narrower generic concept for Lejeunea placing some species included here in Rectolejeunea and Taxilejeunea.  The classification used here follows recent phylogenetic studies that incorporate morphological and molecular characters (J. Heinrichs et al., 2013).  Lejeunea is currently placed in subfamily Lejeuneoideae, tribe Lejeuneeae, subtribe Lejeuneinae.  Other regional genera in the tribe include Harpalejeunea and Microlejeunea (L. Söderström et al.  2016).

SELECTED REFERENCES   Reiner-Drehwald 2003. Lejeunea. In: Gradstein, S. R. & D. Da Costa.  2003.    Hepaticae and Anthocerotae of Brazil. Mem. New York Bot. Garden 87: 155--163.  M. E. Reiner-Drehwald.  1999.  Catalogue of the genus Lejeunea Lib. (Hepaticae) of Latin America.  Bryophytorum Bibliotheca 54:7--101.  Heinrichs, J. et al.  2013.  Molecular phylogeny of the leafy liverwort genus Lejeunea (Porellales): evidence for a neotropoical origin, uneven distribution of sexual systems and insufficient taxonomy.  PLOS One 12: 1--14.  M. E. Reiner-Drehwald.  2000.  Las Lejeuneaceae (Hepaticae) de Misiones, Argentina.  VI.  Lejeunea y Taxilejeunea.  Tropical Bryology 19:  81--131. Schuster, R. M.  1980.  Lejeunea.  In: R. M. Schuster.  1966--1993.  Hepaticae and Anthocerotae of North America.  New York. Vol. 4, pp. 929--1111.

1.  Lobule never saccate, reduced to a small basal fold bearing a linear to lanceolate stylus 1--3 cells wide, 5--12 cells long.

2.  Lobule tooth large, 2--6 cells wide, 8--16 cells long; underleaves distant to contiguous, large (area ca. 0.5 that of adjacent lobe), sinus extending 0.4--0.6 underleaf length, lobes 4--6 cells wide at base …..………21. Lejeunea spiniloba

2.  Lobule tooth small, 1 cell wide, 2--12 cells long; underleaves distant, small (area ca. 0.2 that of adjacent lobe), sinus extending 0.5--0.8 underleaf length, lobes 3--4 cells wide at base ……………………….…22.  Lejeunea trinitensis

1.  Lobule saccate or reduced to a small flap, never modified into an elongated multicellular stylus.

3.  Lateral leaf lobe apex acutely pointed to apiculate, often deflexed, margins of leaves and underleaves crenulate (rarely denticulate).

4. Underleaves large, up to 4 times stem width, area 0.3 that of adjacent lateral leaf lobe, underleaf lobes 8--11 cells wide at base; perianth keels forming rounded, ill-defined longitudinal folds that extend 0.2--0.3 perianth length, keels smooth ……………………18. Lejeunea obtusangula

4. Underleaves smaller, up to 2 times stem width, area 0.1 that of adjacent lateral leaf lobe, underleaf lobes 4--6 cells wide at base; perianth keels forming sharp longitudinal folds that extend 0.75 perianth length, keels crenulate to denticulate …………………….…4. Lejeunea bermudiana

3.  Lateral leaf lobe apex acutely to broadly rounded, plane or slightly deflexed, margins of leaves and underleaves entire (underleaf margin often with tooth in Lejeunea laetevirens).

5.   Specialized asexual reproduction by dehiscent leaves or branches       present.

6.  Plants with microphyllous branches (i.e., stems with leaves                                     consistently smaller than on primary stems).7. Lejeunea cancellata

6.  Plants without microphyllous branches.

7. Plants large (up to 1.5 mm wide); stem in cross-section with 7--12 epidermal cells; pre-dehiscent leaves often decurved, lobules reduced, not

dehiscing with lobe ………19. Lejeunea phyllobola

7.  Plants smaller up to 1 mm wide); stem in cross-section with 5 epidermal cells; pre-dehiscent leaves not decurved, lobules not reduced, dehiscing

with lobe.

8. Dioicous; underleaves up to 2 times stem width; branches with dehiscent leaves,  often erect or arching……10. Lejeunea deplanata

8. Autoicous; underleaves up to 3 times stem width; branches with dehiscent leaves rare, not differentiated from other branches…………………..17. Lejeunea monimiae

5.   Specialized asexual reproduction absent.

9. Plants small (usually less than 0.5 mm wide); lateral leaves distant, rarely contiguous; cell cuticle asperulate; lobule uniformly saccate, large (up to 0.5 lobe length); underleaves distant, small (1--2 times stem width).

10.  Underleaves approximately as wide as stem, underleaf lobe apex acutely rounded, walls of cells near underleaf tip thinner than other underleaf cells and sometimes collapsed ……………………...………………...2.  Lejeunea aphanes

10.  Underleaves up to 2 times wider than stem, underleaf lobe apex sharply acute to attenuate, cells at apex of underleaf lobes not distinctly thinner than elsewhere in underleaf lobe  .………….……………………… 14 Lejeunea laetevirens

9. Plants larger (usually more than 0.5 mm wide); lateral leaves contiguous to imbricate; cell cuticle not asperulate; lobule saccate or reduced, small to medium-sized  (usually 0.2--0.4 lobe length); underleaves distant to imbricate, large 2--4 times stem width.

11.  Lateral leaf lobes deflexed; androecia with bracteoles throughout.

12. Underleaves contiguous to imbricate, up to 4 times stem width, underleaf base rounded to cordate; lobule narrowly ovoid;  known only from Alaska ……………………………..3  Lejeunea alaskana

12.  Underleaves distant, up to 2 times stem width, underleaf base rounded to cuneate; l