Plagiochila simplex (Sw.) Lindenb.

Gradstein, S. Robbert & Reeb, Catherine, 2022, The genus Plagiochila (Dumort.) Dumort. (Marchantiophyta) in Madagascar, Cryptogamie, Bryologie 20 (5), pp. 65-106 : 94

Plagiochila simplex (Sw.) Lindenb.

( Fig. 18 )

Jungermannia simplex Sw. , Nova Genera et Species Plantarum seu Prodromus: 145 (1788). — Plagiochila simplex (Sw.) Lindenb. , Species Hepathicarum (fasc. 2-4): 54 (1840). — Type: Jamaica. Swartz s.n. (holo-, S!).

ADDITIONAL SPECIMENS EXAMINED. — Madagascar. Prov. Fianarantsoa • Andringitra Nat. Park, ridge 6 km E of Pic Boby , IX.1994, Pócs 9475/ H ( EGR, GOET) .

DISTRIBUTION AND HABITAT. — Afro-American: tropical America (widespread), Madagascar (new); new to Africa.In Madagascar found on bark in elfin forest dominated by bamboos at 1450-1700 m.

DESCRIPTION (see also Heinrichs et al. 1998)

Plants small, 1.5-2 mm wide, to 4 cm long, irregularly pinnate, branches intercalary. Creeping, rhizome-like primary stem present. Mature stem leaves distant to contiguous, obliquely to widely spreading, strongly ventrad, asymmetrically ovate to oblong, 1.3-2× longer than wide, widest in the middle, often caducous, base not ampliate and not shouldered, apex irregularly rounded to truncate, often bifid, margins unbordered, curved, toothed near apex by 2-12 short, triangular teeth, the teeth 1-3-4) cells long, the apex sometimes with two larger, lobe-like teeth, the teeth on the ventral margin extending downwards to the lower 1/3 and becoming progressively smaller below, dorsal margin and leaf bases entire; leaf bases shortly and narrowly decurrent, decurrent ventral part c. 0.1 mm long.Leaf cells subisodiametrical, c. 20-35 µm wide in midleaf, 1-1.5× longer than wide, with rather small radiate trigones, cells not thicker-walled to the margin, leaf base without vitta-like area; cuticle smooth; oil bodies not observed. Underleaves absent. Androecia not seen. Perianths on a short stalk, base not covered by bracts. Vegetative reproduction by caducous leaves.

NOTES

Plagiochila simplex (sect. Heteromallae) is a widespread neotropical specides that was recored from La Réunion byLindenberg (1840). The record from La Réunion has not been confirmed, however, and the species was excluded from Africa by Grolle (1995) and Wigginton (2018). The occurrence of P. simplex in Africa is here confirmed.Characteristic are the flaccid plants with obliquely spreading, ventrad, frequently caducous ovate-oblong leaves that are less than 2× longer than wide, with small teeth at apex and along the ventral margin, subisodiametric leaf cells with small radiate trigones, no vitta, and perianths on a short stalk. The species is close to P. pectinata but the leaves in the latter species are more elongate (2-3× longer than wide), leaf cells rectangular and perianths not stalked.

Figures

FIG. 18. ― Plagiochila simplex (Sw.) Lindenb.: A, habit; B, shoot in dorsal view, with intercalary branch; C, shoot in dorsal view; D-F, shoot in ventral view with intercalary branching and stalked perianth; G, leaves; H, leaf apex; I, J, midleaf cells. From Ecuador, Gradstein 12633 (GOET, QCA). Scale bars: A, 5 mm; B-E, G, 1 mm; F, 0.5 mm; H, 0.01 mm; I, 0.05 mm; J, 0.025 mm.