Plagiochila boryana Steph.

Gradstein, S. Robbert & Reeb, Catherine, 2022, The genus Plagiochila (Dumort.) Dumort. (Marchantiophyta) in Madagascar, Cryptogamie, Bryologie 20 (5), pp. 65-106 : 72-76

Plagiochila boryana Steph.

( Fig. 4 )

Plagiochila boryana Steph. , Bulletin de la Société royale de Botanique de Belgique 31 (2): 118 (1892).— Type: France. La Réunion, Rodriguez 174 (lecto-, designated byHeinrichs [2002], G00064121; isolecto-, PC0785962!).

ADDITIONAL SPECIMEN EXAMINED. — Madagascar. Prov. Fianarantsoa • Andringitra Mts. Nat. Park, montane rainforest along tributary W of Korokoro river , 1000-1270 m, IX.1994, Pócs 9473/ AZ ( EGR) .

DISTRIBUTION AND HABITAT. — Afro-American: at high elevation in East Africa ( Uganda, Tanzania) and on La Réunion and Madagascar, furthermore occurring in the mountains of southeastern Brazil and Bolivia where it was described as Plagiochila guttulata Herzog ( Heinrichs 2002) . Plagiochila boryana was recorded from Madagascar by Stephani (1892b, 1893), but this record was not mentioned in Vanden Berghen (1981) and Heinrichs (2002); the occurrence of P.boryana on Madagascar is here confirmed. The species was found in Madagascar on twigs in subhumid mid-elevation forest, 1000-1270 m.

DESCRIPTION (see also Vanden Berghen 1981; Heinrichs 2002)

Plants robust, 5-9 mm wide, little branched, all branches intercalary, rhizome-like creeping shoot present. Mature stem leaves loosely imbricate, widely spreading, alternate, ovate-oblong to ovate-triangular, c. 1.5× longer than wide, widest at the base, ampliate, unbordered, apex rounded,margins with 10-25(-50) teeth, the teeth rather short, 2-5 cells long, mostly linear with a 1-2 cell wide base, present at the apex, along the ventral margin and, occasionally, at the dorsal base; dorsal base longly decurrent, the decurrent part partly covering the stem, ventral base rather shortly and narrowly decurrent. Leaf cells isodiametrical to somewhat elongate, very large, 35-45 µm wide in midleaf, with small trigones, leaf base without vitta-like area; cuticle densely papillose to almost smooth, the papillae numerous per cell, rounded to oblong; oil bodies not observed. Underleaves absent. Male plants slightly smaller than female plants. Androecia in a cluster of 3- 5 male branches at the stem apex. Perianth without stalk, perianth mouth with numerous narrowly triangular or linear teeth. Vegetative reproduction absent.

NOTES

Plagiochila boryana (sect. Hylacoetis Carl) is recognized by the robust plants (more than 5 mm wide) with purely intercalary branching, ampliate leaves with rather short, linear teeth (2-5 cells long, 1-2 cells wide at the base), very large leaf cells (35- 45 µm wide in midleaf)and a papillose cuticle. The papillosity of the cuticle varies and in the Madagassan collection (Pócs 9473/AZ) part of the leaf cells were smooth. The dorsal leaf bases in the species are normally entire ( Heinrichs 2002) but Vanden Berghen (1981) observed toothed dorsal leaf bases in robust populations from the African mainland.

By its large leaf cells P. boryana differs from all Madagassan Plagiochila species except the rare P. macrostachya (synonym: P. granditexta ). The latter species is readily separated from P. boryana by its subopposite leaves, coarser triangular teeth and fully smooth cuticle.

Figures

FIG. 4. ― Plagiochila boryana Steph.: A, habit;B, intercalary branching; C, shoot in dorsal view;D, E, shoot in ventral view,showing ampliate leaf bases; F, leaves; G, leaf margin with teeth; H, I, midleaf cells, showing papillose cuticule. From Bolivia, Heinrichs 4353, 4104 (GOET) and Réunion, Bizot 2985 (PC). Scale bars: A, 5 mm; B, 0.5 mm; C-F, 1 mm; G, 0.1 mm; H, I, 0.05 mm.