Lopholejeunea subfusca (Nees) Schiffn.
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Authority
Thiers, Barbara M. & Gradstein, S. Robbert. 1989. Lejeuneaceae (Hepaticae) of Australia. I. Subfamily Ptychanthoideae. Mem. New York Bot. Gard. 52: 79 p.
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Family
Lejeuneaceae
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Scientific Name
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Description
Species Description - Autoicous; plants to 2 cm long x 1-2 mm wide, dark green to black in the dried condition, on bark or rock. Branching Lejeunea-type, growth habit deliquescent. Stems 100-130 pm in diam., in cross-section composed of 12-14 epidermal cells surrounding 20-30 medullary cells, epidermal cells somewhat larger than medullary cells. Leaves diverging from stem at an angle of approx. 45-75°, contiguous to imbricate, flattened to slightly convex, dorsal lobe asymmetrically ovate to ovate-falcate, 600-850 x 425-650 µm, apex obtusely rounded, margins entire, acroscopic margin straight to rounded at dorsal base, not or slightly overlapping stem, basiscopic margin straight to rounded or arched; marginal cells of dorsal lobe quadrate to rectangular, 10-18 x 10-15 µm, cells of midportion isodiametric to oblong, 25-50 x 25-38 µm, cells of leaf base similar or somewhat larger, 50-55 x 25-38 µm, thin-walled, trigones small to large and bulging, intermediate thickenings small to large. Lobules variable in shape, when well developed basically ovoid but truncate distally, connate to lobe across 1-4 leaf cells, 200-350 x 150-210 µm, 1/3-¼ lobe length, strongly inflated proximally, keel strongly rounded, free margin inrolled proximally, flattened distally, with one single-celled, blunt apical tooth, sinus between tooth and distal edge of lobule straight to slightly lunulate, distal edge of lobule connate to lobe across 2-4 lobe cells; when reduced triangular to ovate, acute to acuminate distally, 120-170 x 120-150 µm, ¼-1/3 lobe length, flattened, keel straight to rounded, free margin flattened or slightly inrolled proximally, apical tooth barely distinguishable, sinus between tooth and distal edge of lobule straight to rounded. Underleaves distant to imbricate, orbicular to transversely oblong, 200-490 x 220-600 µm, 2-4 x stem width, apex rounded, margins entire, base cuneate to rounded, insertion straight. Gynoecia on long or short branches, bracts widely spreading, bract lobes broadly ob-ovate, averaging 900 x 800 µm, apex rounded to acute, margins weakly to strongly dentate-laciniate, bract lobules very small, sometimes explanate, rectangular, averaging 150 x 100 µm, apex truncate, margin entire; bracteoles obovate to flabelliform, weakly to strongly gibbous, averaging 800 x 1000 µm, margins entire. Perianths immersed or occasionally barely emergent, pyriform, averaging 875 x 500 µm (excluding ornamentation), with two strong lateral and ventral keels, occasionally with a trace of a dorsal keel (weakly dentate-laciniate), keels extending ½ to entire perianth length, keel ornamentation variable, ranging from dentate (with teeth 1-2 cells broad at the base and 3-5 cells long) to strongly laciniate (laciniae 2-8 cells broad and 5-25 cells long, with irregularly lobed, often dentate margins). Androecia on short or long branches, composed of 2-10 pairs of bracts.
Distribution and Ecology - Distribution and habitat. This species seems to be one of the few members of Lejeuneaceae subfamily Ptychanthoideae that can survive in fairly disturbed areas of tropical and subtropical Australia. Lopholejeunea subfusca is a pantropical species, occurring in areas of low elevation in subtropical and tropical regions of the Americas, Africa, Asia, and Pacifica.
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Discussion
Jungermannia subfusca Nees, Enum. pl. crypt. Jav. 36. 1830. Phragmicoma subfusca (Nees), Nees, Naturgesch. eur. Leberm. 3: 248. 1838. Lejeunea subfusca (Nees) Nees & Mont, in D’Orbigny, Voy. Amér. Mér. 7: 65. 1839. Symbiezidium subfuscum (Nees) Trevis., Mem. Reale 1st. Lomb. Sci. Mat. Nat. Ill 4: 403. 1877. Type. Java. Blume s.n. & s.d. (holotype, STR? [not available on loan]). Lopholejeunea subfusca is the most common and variable species of the genus in Australia, and thus is likely to give trouble in identification. Remarkably, it has never been reported previously from the continent. The best diagnostic features of L. subfusca are: (1) lobules strongly inflated proximally; (2) apex of lobule truncate and connate to the dorsal lobe across one to four lobe cells; (3) gynoecial bracteoles widely spreading and broadly obovate to flabelliform, gibbous; (4) lobules of gynoecial bracts entire-margined and small, less than ¼ bract lobe length, and 100 µm or less broad; and (5) perianths with four weakly to strongly laciniate keels, rarely with a weak dorsal keel. Any one or more of these features may be lacking, in any combination. Sterile plants with reduced lobules will be very hard to assign with certainty to this species, but fortunately gynoecia can be found in most populations. Generally, plants growing on bark in rain forest areas of high year-round humidity will exhibit more of the abovementioned features than collections from seasonally drier areas, or from unusually wet areas, e.g., near streams or waterfalls.