9. CERATOLEJEUNEA Jack & Stephani, Hedwigia 31: 16. 1892 * [Greek keras, horn, and Lejeunea, name of a related genus].
Barbara M. Thiers
Plants 1--1.5 mm wide, tightly appressed to substrate, brown to reddish brown, microphyllous branches occasionally present. Stems with 7 epidermal cells surrounding 10--20 cortical cells. Lateral leaves widely spreading when dry, plane to convex when moist; 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, convex proximally, plane distally, free margin inrolled for about 0.75--0.9 lobule length, with 1 single-celled, often falcate tooth, hyaline papilla at its proximal base; lobules at stem bases sometimes utriculate (i.e., as large as leaf lobe, strongly inflated with free margin strongly inrolled for entire length). Underleaves distant to contiguous, ovate to orbiculate, 1.5--2 times stem length, 2-fid; lobes erect, triangular; lateral margins entire, basal marginal cells not distinctly larger than adjacent cells, rhizoid disc not differentiated. 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. Gynoecial innovations 1--2, leaf sequence pycnolejeuneoid, bracts somewhat larger than lateral leaves, keel rounded to acutely folded, not winged; perianth with 4 keels forming shoulder-like crests or terete horns that extend beyond apex of perianth.
Species 19 (3 in the flora): pantropical, with greatest diversity in neotropics.
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.
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 compressed, 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 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 undivided 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. ser. 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 areas of subtropical forest (i.e., hammocks); low elevations; Fla.; West Indies; Central America.
Ceratolejeunea ceratantha is known from only two collections in Florida, both of which were treated by R. M. Schuster (1980) as C. rubiginosa Steph. G. Dauphin (2003) identified one of these as C. ceratantha, which he differentiates from C. rubiginosa on the basis of ocelli in a broken line (i.e., ocelli separated by non-ocellate cells) in C. ceratantha rather than in an unbroken line in C. rubiginosa, and a leaf margin dentate only at the apex (as opposed to along the entire antical apex in C. rubiginosa). The Florida collections are scanty and depauperate, but 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 suggest C. ceratantha.
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.