Plagiochila strictifolia Steph.

Gradstein, S. Robbert & Reeb, Catherine, 2022, The genus Plagiochila (Dumort.) Dumort. (Marchantiophyta) in Madagascar, Cryptogamie, Bryologie 20 (5), pp. 65-106 : 98

Plagiochila strictifolia Steph.

( Fig. 21)

Plagiochila strictifolia Steph. , Hedwigia 30: 210 (1891). — Type: Cameroun. Etome, c. 250 m, Dusén 4 (holo-, G; iso-, BM; fide Jones 1962).

SPECIMEN EXAMINED. — Madagascar. Prov. Toamasina • W coast of Masoala Peninsula, S of Ambanizana village , IX.1994, Pócs et al. 9446/ P ( EGR) .

DISTRIBUTION AND HABITAT. — Tropical African lowland species, widely distributed in West Africa, rarer in East Africa ( Wigginton 2004); new to Madagascar. In Madagascar found on bark in remnant humid lowland forest at sea level.

DESCRIPTION (see also Jones 1962; Wigginton 2004) Plants 2-2.5 mm wide, to 5 cm long, flaccid, dichotomous, branches mostly terminal, intercalary branches very few. Creeping, rhizome-like primary stem present. Leaves contiguous, obliquely diverging from the stem in the basal half (at c. 50°) and conspicously arching outwards, horizontally spreading (not ventrad), symmetrically oblong-rectangular, c. 2-2.5× longer than wide, not or very slightly ampliate, apex rounded to subtruncate, plane or slightly undulate, dorsal margin concave, ventral margin convex, the two margins conspicuously running parallel, entire or with 1-4 small triangular teeth at the apex and along the upper ventral margin; dorsal leaf base shortly decurrent, ventral leaf base very shortly decurrent, decurrent part to 0.1 mm long. Leaf cells small, isodiametrical to slightly elongate, c. 15-20 µm wide in midleaf, thin-walled with small trigones, leaf base without vitta-like area; cuticle smooth; oil bodies not observed. Underleaves present, very small, deeply bifid with ciliate lobes. Androecia not seen. Perianth without stalk, perianth mouth densely laciniate. Vegetative reproduction not seen.

NOTES

Plagiochila strictifolia (sect. Vagae) is recognized by the flaccid, dichotomously branched plants with mostly terminal branches, horizontally spreading, oblong-rectangular, non-ampliate, outwards-arching leaves with rounded to subtruncate, subentire apex, ± entire margins, small thin-walled cells, very shortly decurrent leaf bases and small underleaves. In its subentire leaves, P. strictifolia resembles P. repanda but the leaves in the latter species are ampliate, branches are very scarce and mostly intercalary, and the leaf cells have large, swollen trigones.