Plagiochila bifaria (Sw.) Lindenb.

Gradstein, S. Robbert & Reeb, Catherine, 2022, The genus Plagiochila (Dumort.) Dumort. (Marchantiophyta) in Madagascar, Cryptogamie, Bryologie 20 (5), pp. 65-106 : 72

Plagiochila bifaria (Sw.) Lindenb.

( Fig. 3 )

Jungermannia bifaria Sw. , Nova Genera et Species Plantarum seu Prodromus: 145 (1788). — Plagiochila bifaria (Sw.) Lindenb. , Species Hepathicarum (fasc. 5): 127 (1843). — Type: Jamaica. Swartz s.n. (holo-, S!).

ADDITIONAL SPECIMENS EXAMINED. — Madagascar. Prov. Antananarivo • Ankaratra, Manjakatompo Forest Reserve , saddle between Mt. Andriandra and Mt. Ambohimandrana, on soil in montane forest mixed with Plagiochila terebrans , 2050-2130 m, IX.1994, Pócs 9481/ AA ( EGR, GOET) .

DISTRIBUTION AND HABITAT. — Peri-Afro-American (tropical America, Madagascar) and western Europe; new to Africa. In Madagascar found in a mossy montane forest at 2050-2130 m.

DESCRIPTION (see also Heinrichs et al. 1998, 2004a; Paton 1999 as Plagiochila killarniensis Pearson )

Plants 2-3 mm wide, to 4 cm long, irregularly pinnate, all branches intercalary.Creeping, rhizome-like primary stem not observed. Mature stem leaves distant to contiguous, obliquely spreading and strongly ventrad to subtransverse, subfalcate, asymmetrically obovate-oblong, 1.5-2× longer than wide, widest in or above the middle, the upper half or two third often broken away, ventral leaf base not ampliate and not shouldered, apex rounded to truncate, margins unbordered, dorsal margin straight or slighty curved, narrowly recurved, ventral margin arched, leaves with 4-7 widely-spatiated teeth at apex and on the upper half of the ventral margin, two teeth at apex being larger than the other ones, the apex appearing asymmetrically bifid, teeth narrowly to broadly triangular, 2-6(-15) cells long, sometimes broken, made up of subquadrate cells, the tip cell more elongate; leaf bases shortly and narrowly decurrent, the decurrent ventral portion 0.15-0.3 mm long. Leaf cells subisodiametrical to somewhat elongate, 20-30 µm wide in midleaf, 1-1.5× longer than wide, with rather small, well-defined, swollen trigones, the trigones usually not radiate, intermediate thicken - ings occasionally present, leaf base with a conspicuous vitta-like area of larger and wider cells; cuticle smooth; oil bodies not observed. Underleaves absent. Androecia terminal to intercalary, with 3-5 pairs of bracts. Perianth campanulate, exserted beyond the bracts, mouth coarsely toothed, base without stalk. Vegetative reproduction by leaf fragmentation.

NOTES

Plagiochila bifaria (sect. Arrectae Carl) is a widely distributed and highly variable neotropical-western European species that is for the first time recorded from Africa. Characteristic are the fragmenting, subtransverse, obliquely spreading, obovate-oblong leaves with several teeth in the upper half including two larger apical ones (up to 15 cells long), the leaves thus appearing bifid, and the presence of a distinct vitta-like area of larger cells at the leaf base ( Heinrichs et al. 1998, 2004a). The species differs from P. punctata , another member of the sect. Arrectae in Madagascar, by having fragmenting instead of caducous leaves. The Madagassan P. bifaria plants stand out by having rather few teeth per leaf (4-7) and were growing mixed with P. terebrans , but clearly differed from the latter species by the darker brown color and subtransverse, less elongate leaves with an asymmetrically bifid apex.

Figures

FIG. 3. ― Plagiochila bifaria (Sw.) Lindenb.: A, habit; B, dry shoots in lateral view; C, shoots in dorsal view; D, shoot in ventral view;E, intercalary branches (leaves removed); F, leaves; G, leaf apex; H, leaf base; I, J, midleaf cells. From Pócs 9481 (EGR). Scale bars: A-C, F, 1 mm; D, E, 0.5 mm; G, H, 0.25 mm; I, J, 0.05 mm.