Plagiochila punctata (Taylor) Taylor var. paucidentata (Mont. & Gottsche) Gradst., 2022

Gradstein, S. Robbert & Reeb, Catherine, 2022, The genus Plagiochila (Dumort.) Dumort. (Marchantiophyta) in Madagascar, Cryptogamie, Bryologie 20 (5), pp. 65-106 : 88

Plagiochila punctata (Taylor) Taylor var. paucidentata (Mont. & Gottsche) Gradst. , comb. nov.

( Fig. 13 )

Plagiochila paucidentata Mont. & Gottsche, Annales des Sciences naturelles, Botanique (sér. 4) 6: 197 (1856).— Plagiochila mascarena Gottsche, Annales des Sciences naturelles, Botanique (sér. 4) 8: 335 (1857), nom. superfl. — Type: France. La Réunion, C. Richard s.n. (lecto-, designated by Grolle [1995], PC0031004).

Plagiochila emarginata sensu Vanden Berghen (1981) , non typus (fide Grolle 1995).

SPECIMENS EXAMINED. — Madagascar. Prov. Antsiranana • Marojejy Nat. Park , elfin forest on ridge, 1000-1400 m, III.1990, Pócs et al. 90114/ BG ( EGR as P. pectinata ). — Prov. Toamasina • Andasibe-Mantadia Nat. Park, rocky ridge of Mt. Andrianavibe , 950-1050 m, X.1994, Pócs & Szabo 9487/BQ, det. J. Heinrichs as P. punctata ( Heinrichs et al. 2005b) (EGR, GOET) .

DISTRIBUTION AND HABITAT. — East African Islands ( Madagascar, La Reúnion; Mauritius?); first reported from Madagascar byGottsche (1857 as P. mascarena ; fide Grolle 1995), but this record was not mentioned in Vanden Berghen (1981). More recently, this variety has been found twice in Madagascar, growing on bark in ridge forest (elfin forest) at 950-1400 m. In La Réunion var. paucidentata occurs at slightly higher elevation, above 1500 m, on various substrates (bark, soil, rock) in exposed environments ( Vanden Berghen 1981).

DESCRIPTION (see also Vanden Berghen 1981

as P. emarginata )

Plants 1-2 mm wide, 1-5 cm long, sparsely branched, branches intercalary, sometimes denuded by caducous leaves. Mature stem leaves distant to subimbricate, obliquely spreading, ventrad to subtransverse, obovate-oblong, 1.3-1.5(-2)× longer than wide, wideste towards the apex, not ampliate, older stem leaves slightly bordered, apex broadly rounded, margins plane or slightly recurved, entire or with 1-5 small teeth near the apex, the teeth made up of short cells; leaf bases not or shortly decurrent. Leaf cells subisodiametrical, c. 20-30 µm wide in midleaf, trigones small to large and swollen, in older stem leaves becoming larger and confluent along the margin, forming a weakly defined border; leaf base with an ill-defined vitta-like area of larger cells; cuticle smooth; oil bodies not observed. Underleaves absent. Androecia terminal, short, of 4-7 pairs of bracts. Perianth without stalk, perianth mouth with triangular teeth. Vegetative reproduction by caducous leaves, the caducous leaves similar to ordinary leaves.

NOTES

Plagiochila punctata var. paucidentata (Mont. & Gottsche) Gradst. , comb. nov. differs from var. punctata in the more elongate, obovate-oblong leaves, 1.3-2× longer than wide, with margins entire or with 1-5 small teeth near apex. The trigones of leaf cells vary considerably in size and in older stem leaves the trigones tend to become larger and confluent along the margin, forming a weakly defined border.

Figures

FIG. 13. ― Plagiochila punctata (Taylor) Taylor var. paucidentata (Mont. & Gottsche) Gradst., comb. nov.: A, habit; B, shoots in ventro-lateral view; C, shoot in dorsal view; D, shoot in ventral view; E, leaves; F, leaf bases with vitta-like area; G, midleaf cells; H, leaf margin cells; I, female shoot with perianth and innovation. From Szabo 9640/CS, Pócs 0861/R (EGR). Scale bars: A, 5 mm; B-D, I, 0.5 mm; E, 1 mm; F, 0.1 mm; G, H, 0.05 mm.