Plagiochila corrugata (Nees) Nees & Mont.

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

Plagiochila corrugata (Nees) Nees & Mont.

( Fig. 5)

Jungermannia corrugata Nees , Flora Brasiliensis seu Enumeratio Plantarum 1 (1): 378 (1833). — Plagiochila corrugata (Nees) Nees & Mont., Annales des Sciences naturelles, Botanique (sér. 2) 5: 52 (1836). — Type: Brazil. Martius s.n. (holo-, STR; fide Heinrichs et al. 2004b).

Plagiochila cambuena Steph. , Botanical Gazette 15: 289 (1890) — Type: Madagascar ( Vanden Berghen 1981; Heinrichs et al. 2004b).

Plagiochila madagascariensis Steph. , Bulletin de l’Herbier Boissier (sér. 2) 4 (6): 594 (1904), nom. illeg. — Type: Madagascar ( Vanden Berghen 1981).

Plagiochila undulata Dugas, Annales des Sciences naturelles, Botanique (sér. 10) 11: 121, 188 (1928), nom. illeg. — Type: Madagascar ( Grolle 1995).

SPECIMENS EXAMINED. — Madagascar. Plateau de Ikanga, Besson 326 ( PC). — Prov. Antsiranana • Marojejy Reserve, Mandena, III.1990, Pócs et al. 90110/ A ( EGR as P. repanda, GOET ). — Prov. Antananarivo • Bonjolava Forest, IX.1974, Cremers 3444 ( BR); Lake Mantasoa, VIII.1959, Bosser 13122 ( BR); III.1974, Onraedt 70 M2171 ( BR); VII.1998, Pócs et al. 9851/ A ( EGR); Mandraka Forest , Onraedt 70 M2176 , 70 M2193 ( BR).— Prov. Fianarantsoa • Ambositra, Amalatery, on trees, 1800 m, Onraedt 70 M0396 ( EGR as P. rodriguezii ); Andringitra Nat. Park, VII.1955, Bosser 9632 ( BR); Pic Boby , IX.1994, Vojtkó 9458/ H, 9458/ W ( EGR); tributary W of Korokoro river , Pócs 9473/ AV ( EGR); Ifanadiana , Ranomafana village , VII.2004, Pócs 04122/ B ( EGR); Ranomafana Nat. Park , Namorona river waterfalls, VII.2004, Pócs 04126/ AS ( EGR); slope of Mt. Vatolampy near Ambatolahy village , Pócs 04129/AB ( EGR, GOET), 04129/ AC, 04129/ H ( EGR) .

DISTRIBUTION AND HABITAT. — Afro-American: in Africa largely restricted to East Africa, in tropical America occurring in southern subtropical regions (southeastern Brazil, northern Argentina, Paraguay, Bolivia). Its distribution resembles that of P. boryana . In Madagascar P. corrugata is found on bark and rock in humid to subhumid evergreen forests and coffee plantations, from sea level to 2000 m.

DESCRIPTION (see also Vanden Berghen 1981 as P. cambuena ; Heinrichs et al. 2004b)

Plants 2-4 mm wide, to 8 cm long, rigid, irregularly pinnate, dichotomous in younger parts, branching terminal and intercalary. Creeping, rhizome-like shoot present, short. Stem surface without paraphyllia (but teeth on the decurrent ventral leaf bases and on underleaves may sometimes resemble paraphyllia). Mature stem leaves imbricate and ventrad, obliquely spreading and somewhat curved outwards, very asymmetrical, ovate-triangular, 1-1.5× longer than wide, ampliate, ventral margin strongly undulate-crispate over most of its length but without teeth except at the base (in plants from Madagascar), apex entire or with a few short teeth, dorsal margin narrowly recurved, entire; dorsal bases longly and broadly decurrent, concealing the stem, ventral base longly and broadly decurrent, usually more than 0.2 mm long, undulate and with a few cilia and lacinia. Leaf cells subisodiametrical, c. 18-25 µm wide in midleaf, rather thin-walled, with small cordate to slighly swollen trigones; vitta-like area absent; cuticle smooth; oil bodies not observed. Underleaves present, up to 0.5 mm long, deeply bifid, outer margins often with cilia or lacinia. Androecia terminal to intercalary, of 4-10 pairs of bracts. Perianth without stalk, perianth mouth densely toothed by shortly triangular teeth. Vegetative reproduction by cladia from ventral leaf surfaces.

NOTES

Plagiochila corrugata (sect. Vagae) is recognized by the rigid, irregularly (bi)pinnate to dichotomous plants with terminal and intercalary branches, and with ampliate, ventrad leaves with strongly undulate-crispate ventral margins and longly and broadly decurrent bases, which are concealing the stem surface. Underleaves are present. By the undulate-crispate ventral leaf margins P. corrugata is similar to P. squamulosa and P. rodriguezii , but P. rodriguezii differs in the shortly and narrowly decurrent ventral leaf bases without cilia or lacinia on the decurrent strip, absence of underleaves, and smaller leaf cells (10-20 µm wide in midleaf) with large trigones and angular-undulate lumina. Plagiochila squamulosa , a common and variable species in the mountains of East Africa ( Jones 1962; Vanden Berghen 1981) that is very rare in Madagascar, is more closely similar to P. corrugata , but differs by numerous small paraphyllia on the ventral stem surface. The paraphyllia can be confused with underleaves and lacinia of ventral leaf bases, but differ from the latter by the rounded cells of the paraphyllia, those of amphigastria and lacinia being quadrate to elongate.

Vanden Berghen (1981) noted a close morphological similarity between P. corrugata (synonym: P. cambuena ) and P. ulata Inoue & Grolle from New Guinea. However, the latter species has undulate dorsal leaf margins ( Piippo 1989); in P.corrugata the dorsal leaf margins are plane.