BFNA Title: Macrodiplophyllum
Author: D. H. Wagner
Date: Jan. 10, 2017
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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XXX. MACRODIPLOPHYLLUM (Buch) Persson, Svensk Bot. Tidskr. 43: 507. 1949 [Latin macro, large, Latin diplophyllum, doubled leaf; alluding to a related genus with conduplicate leaves]

 

David H. Wagner

 

 

Plants 10--110 x 2--4 mm, ascending to erect, in tufts or scattered among other bryophytes, yellowish green to pale olive green or greenish brown, sometimes tinged red near apex. Stems 300--400 x 350--500 \um;  outer cortical cells thick walled in (1--)2--4 layers, yellowish green near apex, becoming dark brown to black with age, branches few, lateral or ventral, often as paired innovations below gynoecia. Leaves contiguous to imbricate, complicate 2-lobed with smaller dorsal and larger ventral lobes, dorsal to ventral lobe length ratio 0.3--0.9;  dorsal lobe 2 x 1 mm, subtransversely inserted, insertion line extending partially across stem to wrapping around opposite side of stem, decurrent to 0.2 width of stem or not decurrent, spreading 30--80º from stem axis, obliquely obovate, oblong to strap shaped, usually slightly convex, outer margin parallel to line of keel, 0.5--2 mm; ventral lobe to 2.8 x 1.6 mm, transversely inserted, insertion line slightly arched, not decurrent or decurrent to 0.1--0.2 of stem width, midline spreadng 60--90º from stem axis, oblong, obliquely obovate to spatulate, straight or weakly falcate, slightly convex, spreading to deflexed;  keel keel strong, not winged, straight to curved, 0.25--0.7 of ventral lobe length; margins entire to strongly but unevenly spinose-dentate, apices often eroded from gemma production; cells at leaf base elongate rectangular, trigones bulging with nodose cell walls, to 95 x 25 \um; median cells cells polygonal, mostly isodiametric, usually with bulging trigones,  30 x 25 \um,  marginal cells with evenly thickened walls usually forming a distinct border in 2---3(--4) rows, one species without a definite border; cuticle rarely nearly smooth, usually striolate to verruculose, in one species strongly papillose; oil bodies 2--10 per cell, usually finely granulose, rarely of amorphous texture, clear to pale brown. Specialized asexual reproduction by gemmae, produced in masses on leaf margins at shoot apex, 2--4 celled, angular, rounded polygonal or oval, outer walls thick, inner walls intersecting. Sexual condition dioicous; sporophytes rarely observed. Androecia terminal, rarely observed, unknown in most species, male bracts similar to vegetative leaves but gibbous, closely overlapping. Gynoecia terminal, often producing paired innovations below unfertilized perianth, female bracts in one pair, similar to vegetative leaves but larger and more prominently dentate. Perianth rare in most species, cylindrical to slightly flattened, pluriplicate to the base or occasionally plicate only in distal half, weakly dorsiventrally compressed, mouth lobulate or lacerate with slender, sometimes branched, lobulae to 20 cells long. Capsule with walls 3--4(--5) stratose, elaters 2-spiral, spores 15--18 /um, minutely punctate or verruculose.

 

Species 5 (5 in the flora), close to Pacific Ocean in an arc from Japan and Korea north through Russian Far East, sporadically to Yakutia and Baikal Siberia, across the Aleutian Archipelago and down the west coast of North America to northern California.

 

The genus Macrodiplophyllum is distinguished by its robust habit, rounded, lingulate leaf lobes, elongated basal laminal cells, perianth pluriplicate usually to the base, perianth mouth constricted and lobulate or laciniate-ciliate, with few to many branched cilia. It is a member of cool temperate rain forest ecosystems, primarily terrestrial on peaty soil, in crevices between rocks, on cliff faces, and occasionally corticolous on tree bases or downed logs. It is a natural biogeographic group characterized by an array of ancestral traits. Molecular phylogenetic analysis shows that Macrodiplophyllum in a broad sense is derived from the more generalized genus Diplophyllum and is basal to two more specialized genera, Douinia and Scapania (Heinrichs et al. 2012). Alternate classifications would place the three historically recognized species of Macrodiplophyllum in Diplophyllum (Hong 1980), all in Scapania (Potemkin 2002), or assign one species to Scapania and two to Douinia (Konstantinova et al. 2013). The two recently described species, M. flaccidum and M. rubrum  (Wagner 2016), have yet to be subjected to molecular phylogenetic analysis.

 

SELECTED REFERENCES  Choi, S. S., V.A. Bakalin, and B. Sun. 2012. Scapania and Macrodiplophyllum in the Russian Far East. Bot. Pacifica 1: 31--95. Heinrichs, J., A. Bombosch, K. Feldberg, H. P. Kreier, J. Hentschel, J. Eckstein, D. Long, R.L. Zhu, A. Schäfer-Verwimp, A. R. Schmidt, B. Shaw, A. J. Shaw & J. Váňa. 2012. A phylogeny of the northern temperate leafy liverwort genus Scapania (Scapaniaceae, Jungermanniales). Mol. Phylog. Evol. 62: 973--985. Konstantinova N. A., A. A. Vilnet, L. Söderström, A. Hagborg, M. J. von Konrat. 2013. Notes on Early Land Plants Today. 14. Transfer of two Macrodiplophyllum species to Douinia (Scapaniaceae, Marchantiophyta). Phytotaxa 76(3): 31--32. Potemkin, A. D. 2002. Phylogenetic system and classification of the family Scapaniaceae Mig. emend. Potemkin (Hepaticae). ). Ann. Bot. Fenn. 39: 309--334. Vilnet, A. A., N. A. Konstantinova and A. V. Troitsky. 2011 [“2010”].  Molecular insight on phylogeny and systematics of the Lophoziaceae, Scapaniaceae, Gymnomitriaceae and Jungermanniaceae. Arctoa 19: 31--50. Wagner, D. H. 2016. Two new species of Macrodiplophyllum (Marchantiophyta) endemic to western North America. Phytoneuron 2016-57: 1--22.

 

1.  Dorsal lobe base reaching across stem, the base tightly wrapped around stem opposite the keel; ventral lobe base with a well-defined strip of thick-walled marginal cells armed with closely set, slender, unicellular, spinose teeth; spinose strip often strongly red pigmented.

 

2.  Cuticle faintly striolate to verruculose; leaves contiguous, evenly spaced so the keel is usually exposed at stem to leaf junction; midline of distal half of ventral lobes spreading 55--85º from stem; spinose strip at base of ventral lobe usually bright orange-red …..5. Macrodiplophyllum rubrum

 

2.  Cuticle strongly papillose with several globose papillae over each median cell; leaves mostly imbricate with few keels exposed; midline of distal half of ventral lobes spreading 80--90º from stem; spinose strip at base of ventral lobes not pigmented ….. 2. Macrodiplophyllum microdontum

 

1.  Dorsal lobe base reaching 0.5--0.9 across stem but not wrapped around opposite side; ventral lobe base entire or with scattered marginal teeth, low or up to 4 cells in length, not spinose; margins not pigmented or at most light pink.

 

3.  Dorsal lobes 0.8--0.9 as long as ventral lobes, about as broad as ventral lobes; margins uniformly entire ….. 4. Macrodiplophyllum imbricatum

 

3.  Dorsal lobes less than 0.7 as long as ventral lobes, much narrower than ventral lobes; margins sparsely to moderately dentate, at least at apex of lobes.

 

4.  Distal half of ventral lobe spreading less than 75º from stem; lobes with small, inconspicuous teeth; leaf form changed little upon drying …..3.  Macrodiplophyllum plicatum

 

4.  Distal half of ventral lobe spreading close to 90º from stem; both lobes regularly dentate, teeth usually prominent at lobe apices; leaves wilted and contorted when dry   …..1. Macrodiplophyllum flaccidum

 

1. Macrodiplophyllum flaccidum D.H. Wagner, Phytoneuron 2016-57: 8. 2016 [E]

 

Plants 20--60 x 2--4 mm, ascending to erect, yellowish green to pale olive green, sometimes tinged red near apex. Stems 335--370 x 235--260 \um, outer cortical cells thick walled in 2--4 layers, olive green at apex, dark brown to black below, sparsely branched. Leaves contiguous to mostly imbricate; dorsal to ventral lobe length ratio 0.5--0.7;  dorsal lobe 1.2--1.6 x 0.5--0.8 mm, subtransversely inserted, insertion line weakly arched, weakly decurrent for 0.1--0.2 of stem width, midline smoothly curved from base to apex, spreading 30--80º from stem axis, obliquely obovate to arcuate, flat to slightly convex, apex obtuse to rounded, basal margin reaching across stem not quite to opposite side; ventral lobe 1.4--1.9 x 0.4--0.9 mm, transversely inserted, insertion line slightly arched, decurrent for 0.1--0.2 of stem width, midline spreading 60--90º from stem axis, obliquely obovate to spatulate, weakly falcate, slightly convex, contorted when dry; keel curving evenly from base, often dark brown to black, 0.3--0.5 of ventral lobe; cells at leaf base elongate-rectangular, 36--40 x 18-20 \um, trigones strongly bulging, walls nodose; median cells (15--)20--26(--27) \um, trigones bulging, margins with evenly thick walled cells in 2--3 cell rows, finely dentate with few teeth at lobe bases but teeth regularly produced on distal third except where eroded by gemma production, apex of ventral lobe with occasional multicellular teeth; cuticle smooth; oil bodies 2--3(--4) per cell, reniform-fusiform, amorphous texture, pale brown, nearly filling cell lumen. Specialized asexual reproduction not known. Sexual condition dioicous. Androecia occasional, becoming intercalary, male bracts average 6, similar to vegetative leaves but strongly gibbous at base. Gynoecia terminal, female bracts like vegetative leaves but larger and more prominently dentate-spinose. Perianth frequent, deeply plicate in distal half only, long emergent, mouth lacerate with slender, sparsely branched lobulae up to 8 cells long.

 

Wet rocks or soil between rocks, often on streamside cliffs; B.C.; Alaska, Wash.

 

Macrodiplophyllum flaccidum is most similar to M. plicatum in morphology and ecology. Both occur almost exclusively on inorganic substrates such as cliff faces, boulders, and sandy soil. One of the most distinctive characters of M. flaccidum, dry and contorted leaves, is seen only in dried specimens. Therefore, it is more easily recognizable in the herbarium than in the field. The presence of a prominent black keel and black stem is suggestive but not diagnostic. Whereas most species of this genus have at least some roughening of the cuticle, striolate, verruculose to papillose, the cuticle of M. flaccidum is usually quite smooth making the plants appear glossy or shiny when dry. Dry specimens of M. plicatum have a distinctly velvety or satiny appearance.

 

2. Macrodiplophyllum microdontum (Mitten) Persson, Svensk Bot. Tidskr. 43: 507. 1949

 

Martinellius microdontus Mitten, Trans. Linn. Soc. London, Bot. 3: 196. 1891; Diplophyllum microdontum (Mitten) H. Buch; Scapania microdonta (Mitten) Müller Freib.

 

Plants 30--70 x 4--4.4 mm, ascending to erect, yellowish green to brownish green or fuscous brown. Stems 300--350 x 500--550 \um, outer cortical cells thick walled in 2--4 layers, yellowish green near apex and fuscous brown below, sparsely branched. Leaves closely imbricate; dorsal to ventral lobe length ratio 0.5--0.6; dorsal lobe  1.6--2 x 0.8--1 mm, subtransversely inserted, insertion line slightly arched, weakly decurrent for 0.1--0.2 of stem width, spreading 35--50º from stem axis, obliquely oblong to ovate, slightly convex,  apex rounded, basal margin auriculate, arching over stem and wrapped around opposite side; ventral lobe  2--2.6 x 1.2--1.6 mm, transversely inserted, insertion line slightly arched, decurrent for 0.1--0.2 of stem width, midline angled 70--85º from stem axis, obliquely oblong to obovate, slightly convex; keel 0.25--0.35 of ventral lobe, semicircularly arched, diverging 30--50º from stem axis at the base, curving away to 110--140º at the distal end; cells at leaf base elongate, 50--75 x 18--25 \um, trigones strongly bulging; median cells 25--37 x 25--30 \um, trigones strongly bulging,  marginal cells with bulging trigones like median cells; ventral lobe base with a well defined marginal border of thick-walled cells 2--5 cells wide extending up to 1 mm from point of insertion, armed with closely set, slender, unicellular, sometimes recurved spinose teeth, denticulate to dentate at apex with sharp, unicellular teeth over 2 times longer than wide, sometimes eroded by gemma production; oil bodies 4--6(--8) per cell, spherical to elliptical, 5.5--7.5 x 5--6 \um, granulose. Gemmae uncommon, produced in masses at apices of leaves, oval to rounded polygonal, 2--4 celled, brown.  Sexual condition presumed dioicous. Androecia not known. Gynoecia terminal. Perianths rare, deeply plicate, long emergent, mouth lobulate-ciliate, the lobululae 8--16 cells long.

 

Arctic and subarctic; shaded rocks, cliffs, crevices in gravelly barrens; B.C., Yukon; Alaska; Asia (Russian Far East, Southern Siberia).

 

Macrodiplophyllum microdontum is distinctively characterized by dramatically large, bulbous papillae crowded on the  cuticle of the leaves.  This species is sparsely distributed over a wide area. Plants bearing perianths have not been seen in North America.

 

3. Macrodiplophyllum plicatum (Lindberg) Persson, Svensk Bot. Tidskr. 43: 507. 1949

 

Diplophyllum plicatum  Lindberg, Contr. Fl. Crypt. As., 235. 1872; Scapania plicata (Lindberg) Potemkin; Douinia plicata (M. Howe) Konstantinova et Vilnet

 

Plants 20--60 x 2--4.8 mm, in small patches, ascending to erect, yellowish green to brownish green. Stems 300--350 x 500--550 \um, outer cortical cells thick walled in 2--4 layers, yellowish green near apex and fuscous brown below, sparsely branched, mostly ventral. Leaves contiguous to mostly imbricate; dorsal to ventral lobe length ratio 0.4--0.5; dorsal lobe 1.2--1.6 x 0.5--0.8 mm, subtransversely inserted, insertion line weakly arched, weakly decurrent for 0.1--0.2 of stem width, spreading 35--50º from stem axis, obliquely obovate, lingulate to spatulate, flat to slightly convex, apex rounded, basal margin reaching across stem to opposite side; ventral lobe  2.0--2.8 x 0.9--1.4 mm, transversely inserted, insertion line arched, not decurrent, midline spreading 70--85º from stem axis, obliquely obovate to spatulate, weakly falcate, slightly convex; keel 0.3--0.4 of ventral lobe length, diverging 10--30º from stem axis at base and gradually curving up to 80--100º at the end; cells at leaf base elongate, 30--70 x 17.5--35 \um, trigones bulging; median cells 18--32.5 x 17--25 \um, trigones bulging,  evenly thick walled cells in 2--3 cell rows at margin, margins denticulate to dentate at least at apex of ventral lobe; cuticle striolate to verrucose; oil bodies 5--8(--10) per cell, spherical to elliptical, granulose. Gemmae uncommon, produced in masses at apices of leaves, distinctly angular, 2(--4) celled, brown. Sexual condition presumed dioicous. Androecia not known. Gynoecia terminal, female bracts in one pair, larger than sterile leaves, dorsal lobe to 1.7 mm, ventral lobe to 2.9 mm. Perianth rare, cylindrical, pluriplicate, weakly dorsiventrally compressed, 4--5 x 1--12 mm, mouth shallowly lobulate, lobe margins dentate with 1--3 celled teeth.

 

Terrestrial, on shaded rocks, crevices in gravelly barrens, humus along stream bed or coniferous forest floor; B.C.; Alaska, Wash.; Asia (Japan, Russian Far East).

 

Macrodiplophyllum plicatum is most similar to M. flaccidum. The dense, finely granular papillae on the cuticle of M. plicatum gives leaves when dry a satin like sheen, in contrast to the glossy dried leaves of M. flaccidum. The keel of M. plicatum is moderately curved while that of M. flaccidum curves in a semicircle. The dorsal and ventral lobes of M. plicatum are both relatively straight  and diverge at differing angles from the stem while the lobes of M. flaccidum curve away in a parallel fashion. Habitat and substrate are quite variable over the range of the species. The typical form has lingulate leaves that are sparingly dentate. There is an uncommon form which has broader, more obovate and more strongly dentate lobes, occuring throughout the range of the typical form. It is more often found on tree bases than the typical form; it will likely prove to be distinct upon further study.

 

4. Macrodiplophyllum imbricatum (M.A. Howe) Persson, Svensk Bot. Tidskr. 43: 508. 1949

 

Scapania imbricata M. Howe, Bull. New York Bot. Gard. 2(6): 104. 1901; Diplophyllum imbricatum (M. Howe) Müller Freib. ex Stephani; Douinia imbricata (M. Howe) Konstantinova et Vilnet; Diplophyllum hyalinum Brinkman ex Frye et Clark

 

Plants 10--40 x 2.5--3.5 mm, in tufts, ascending to erect, olive green to brownish green. Stems 400--450 x 250--350 \um, outer cortical cells thick walled in 1--2(3) layers, olive green at apex, fuscous brown below, sparsely branched. Leaves closely imbricate; dorsal to ventral lobe length ratio 0.8--0.9;  dorsal lobe 1.1--1.5 x 0.6--0.7 mm, subtransversely inserted, insertion line weakly arched, not decurrent, angled 30--50º from stem axis, obliquely obovate to spatulate, slightly convex,  apex rounded, basal margin arching over stem to opposite side; ventral lobe 1.6--1.8 x 0.7-0.8 mm,  transversely inserted, insertion line arched, not decurrent, midline angled 60--80º from stem axis, obliquely obovate to spatulate, slightly falcate and convex, apex rounded; keel 0.3--0.4 of ventral lobe length,  diverging 10--30º from stem axis at base and gradually curving up to 90--110º at the end; cells at leaf base elongate-rectangular, 62.5-85 x 20--25 \um, trigones bulging to nodose; median cells 25--25 x 20--29 \um, trigones bulging,  evenly thick walled cells in 2--3 cell rows at margin, margins entire throughout; cuticle striolate to weakly verrucose; oil bodies (3--)4---5(--7), mostly spherical, granulose. Gemmae rare, produced in masses at apices of leaves, spherical to angular, 2--4 celled, brown. Sexual condition presumed dioicous. Androecia not known. Gynoecia not known.

 

Montane to subalpine, on shaded rocks in stony fields, open rocky hillsides, or crevices in gravelly barrens; B.C.; Alaska; Asia (Russian Far East).

 

Macrodiplophyllum imbricatum has strictly entire leaf margins, unique in the genus. Also distinctive are the dorsal lobes being as broad or broader than the ventral lobes and consistently so closely inserted that the keel is never visible without dissection. Only the broad lobed form of M. plicatum is likely to be mistaken for this species; M. plicatum always has margins dentate at least at the apex of ventral lobes.

 

5. Macrodiplophyllum rubrum D. H. Wagner, Phytoneuron 2016-57: 1. 2016 [E]

 

Plants 20--110 x 2--4 mm, ascending to erect, in tufts or scattered among other bryophytes, yellowish green to pale olive green. Stems 440--520 x 320--350 \um; a single layer of outer cortical cells thick walled, olive green at apex, dark brown to black below, branches lateral, frequently produced as paired innovations subtending unfertilized gynoecia. Leaves imbricate-sheathing at base, spreading, distally pectinate, not imbricate; dorsal to ventral lobe length ratio 0.45--0.7; keel nearly straight  and parallel to antical margin of lobes, 0.45--0.7 of ventral lobe length;  dorsal lobe  1.1--1.5 x 0.6--0.7 mm, subtransversely inserted, insertion line weakly arched, not decurrent, spreading 40--55º from stem axis, oblong to strap shaped, slightly convex,  apex rounded, lobe base auriculate, reaching across stem and tightly wrapped around opposite side; ventral lobe 2.0--2.6 x 0.8--1.2 mm, transversely inserted, insertion strongly line arched, decurrent to half the stem width, midline angled 55--85º from stem axis, strap shaped, apex rounded, strongly convex, often deflexed when dry; cells at leaf base elongate-rectangular, 75--95 x 17--20 \um, trigones bulging, cell walls nodose thickened; median cells (18--)20--23(--27) \um, trigones concave to moderately bulging, margins evenly thick walled cells in 2--3 cell rows, more strongly thickened at base of ventral lobe, where 2--5 cells wide, extending up to 1 mm  from point of insertion, armed with closely set, slender, unicellular, sometimes recurved spinose teeth, the spinose strip usually strongly red pigmented at tip of shoot, darkening with age; cuticle striolate to weakly verrucose; oil bodies 5--8(--10) per cell, spherical to elliptical, granulose. Gemmae frequent, produced in masses at apices of leaves, spherical to rounded polygonal, 2(--4)-celled, pale tan. Sexual condition dioicous. Androecia not known. Gynoecia terminal, female bracts in one pair, larger than sterile leaves, dorsal lobe to 1.7 mm, ventral lobe to 2.9 mm; small bractlets sometimes included. Perianth occasional, deeply plicate to base, long-emergent, mouth lobulate-ciliate, lobulae branched, slender, sharp tipped, 6--10(--20) cells long, 1--4 cells wide.

 

Restricted to organic substrates; most common on bark of trees near their base and on decaying logs in coniferous forests or in more northern sites on peaty humus; B.C.; Alaska, Calif., Oreg., Wash. 

 

The frequent occurrence of Macrodiplophyllum rubrum on tree bases is in striking contrast to the predominantly rock and soil substrates favored by all other species of the genus. The most prominent diagnostic characteristic of this species, the bright red, spinose margin of the ventral lobes, is quite easily detected in the field with a hand lens. Although superficially quite different in general appearance, M. rubrum shares some fundamentally distinctive characters with M. microdontum: strongly differentiated, broad, spinose margin at the base of the ventral lobe and a dorsal lobe that wraps around the stem. Their ranges do not overlap.