Plagiochila drepanophylla Sande Lac.

Gradstein, S. Robbert & Reeb, Catherine, 2022, The genus Plagiochila (Dumort.) Dumort. (Marchantiophyta) in Madagascar, Cryptogamie, Bryologie 20 (5), pp. 65-106 : 77-78

Plagiochila drepanophylla Sande Lac.

( Fig. 6)

Plagiochila drepanophylla Sande Lac. , Synopsis Hepaticarum Javanicarum: 103 (1857).— Type: France. La Réunion, unknown collector (holo-, L; fide Vanden Berghen 1981).

Plagiochila dicrana Mitt. , Journal and Proceedings of the Linnean Society of London 22: 320 (1886). — Type: Madagascar ( Grolle 1995).

SPECIMENS EXAMINED. — Madagascar. Prov. Antsiranana • Marojejy Nat. Park, elfin forest on ridge, 1000-1400 m, III.1990, Pócs 90114/ BJ ( EGR). — Prov. Antananarivo • Lake Mantasoa , III.1974, Onraedt 70 M2116 ( BR); IV.1986, Tixier 8234 ( BR); Angavokely, near Carion, I.1970, Onraedt 70 M82 ( BR).— Prov. Fianarantsoa • c. 33- 34 km S of Ambositra, c. 1650 m, VIII.1871, Onraedt 70 M5380 , 70 M5324 a ( BR); IX.1994, Pócs 9479/ E ( EGR); Ankazonivady Forest Reserve, 16 km S of Ivato , VII.2004, Pócs et al. 04115/ Q ( EGR); Ramomafana Nat. Park , W slope of Mt. Vatolampy , VII.2004, Pócs 04129/ F ( EGR); summit ridge of Mt. Vatolampy , Pócs 04128/ F ( EGR); beyond park boundary, Mt. Namatoana , Pócs & Tuba 04130/AQ ( EGR); between Fianarantsoa and Mananjary, Besson s.n., isosyntype of Plagiochila valida Steph. ( PC0103073 !). — Prov. Toamasina • near Moramanga, X.1994, Pócs 9489 ( EGR, GOET); Andasibe-Mantadia Nat. Park, Mt. Andrianavibe , X.1994, Pócs 9487/BV, 9487/ CJ ( EGR) .

DISTRIBUTION AND HABITAT. — East Africa ( Tanzania), Madagascar, La Réunion. In Madagascar found on bark in humid or subhumid mid-elevation and montane forests, 900-2000 m.

DESCRIPTION (see also Jones 1962; Vanden Berghen 1981) Plants 2.5-4.5 mm wide, to 5 cm long, dichotomous or slightly and irregularly pinnate, branching terminal and intercalary, rhizome-like creeping shoot present. Mature stem leaves contiguous to subimbricate, suberect in the lower half, widely and horizontally spreading in the upper half, very asymmetrical, narrowly triangular-falcate, c. 2-3× longer than wide, widest near the base, ampliate, the ampliate ventral leaf bases sometimes forming an undulate crest that is concealing the stem; branch leaves less ampliate; leaf margins unbordered (but cells sometimes slightly more elongate-rectangular towards leaf margin), apex usually bifid, with (1-)2 very long, lobe-like teeth (to 0.3 mm long), the apical teeth erect to widely diverging (divariacate), ventral margin entire or with a few linear to narrowly triangular teeth (1-7), dorsal margin without or with one small tooth near apex, ventral and dorsal bases entire, dorsal bases longly and rather broadly decurrent, concealing the stem, ventral base conspicuosuly and very narrowly decurrent, the linear decurrent portion to 0.2 mm long, entire. Leaf cells c. 15-20 µm wide in midleaf, subrectangular, 1.5-2× longer than wide, the cells with conspicuous trigones, trigones cordate to swollen and slightly trabeculate; vitta-like area absent; cuticle smooth; oil bodies not observed. Underleaves present, very small, deeply bifid. Androecia terminal to intercalary, of 3-6 pairs of bracts. Perianth without stalk, perianth mouth densely ciliate. Vegetative reproduction by regenerants from leaf surfaces ( Vanden Berghen 1981).

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NOTES

Plagiochila drepanophylla (sect. Vagae) is readily recognized by the conspicuously falcate, asymmetrically bifid leaves with two large, sometimes widely, divaricately spreading teeth, longly decurrent dorsal and ventral leaf bases. Branching is terminal and intercalary. In the elongate leaf cells and conspicuously bifid apex, the species approaches members of the neotropical section Fuscolutea , especially P. aerea and P. tabinensis . The relationships of this species to other members of sect. Vagae, where Heinrichs et al. (2005a) place the species, are unclear and need study.

The isosyntype material in PC of P. valida Steph. (synonym: P. barteri var. valida [Steph.] VandenBergh.) from Madagascar, Besson s.n., is a poorly preserved specimen of P. drepanophylla .