Plagiochila terebrans Nees & Mont.

Gradstein, S. Robbert & Reeb, Catherine, 2022, The genus Plagiochila (Dumort.) Dumort. (Marchantiophyta) in Madagascar, Cryptogamie, Bryologie 20 (5), pp. 65-106 : 98-102

Plagiochila terebrans Nees & Mont.

( Fig. 22 )

Plagiochila terebrans Nees & Mont. , Species Hepathicarum (fasc. 2-4): 98 (1840). — Type: France. La Réunion, C. Richard s.n. (lecto-, designated here, PC0699835 [=MB3436]!; isolecto-, PC0699833! [=MB3435]). In the protologue no collector is cited, but in Synopsis Hepaticarum ( Gottsche et al. 1844: 36) Richard is cited as the collector of the type.

Plagiochila angustissima Steph. , Bulletin de l’Herbier Boissier (sér. 2) 2 (12): 975 (1902). — Type: Madagascar ( Jones 1962).

Plagiochila berthieui Steph. , Bulletin du Jardin botanique national de Belgique 32: 36 (1893). — Type: Madagascar ( Vanden Berghen 1981).

Plagiochila borgenii Gottsche, Abhandlungen des Naturwissenschaftlichen Vereins zu Bremen 7: 341 (1882), nom. inval. — Type: Madagascar ( Grolle 1995).

Plagiochila fissicalyx Steph. , Bulletin de l’Herbier Boissier (sér. 2) 2 (12): 970 (1902).— Type: Madagascar ( Vanden Berghen 1981).

Plagiochila hildebrandtii Steph. , Bulletin de l’Herbier Boissier (sér. 2) 2 (12): 982 (1902). — Type: Madagascar ( Vanden Berghen 1981).

Plagiochila laxifolia Gottsche, Abhandlungen des Naturwissenschaftlichen Vereins zu Bremen 7: 339 (1882).— Type: Madagascar ( Jones 1962; Grolle 1995).

Plagiochila replicatula Steph. , Bulletin de l’Herbier Boissier (sér. 2) 2 (12): 982 (1902).— Type: Madagascar ( Vanden Berghen 1981).

Plagiochila sublinearis Gottsche, Abhandlungen des Naturwissenschaftlichen Vereins zu Bremen 7: 341 (1882).— Type: Madagascar ( Grolle 1995).

A B D C G F J E H I

A B E F C D G H J K I

ADDITIONAL SPECIMENS EXAMINED. — Madagascar. Forêt d’Amperifery, Campenon 246 as “ P. rutenbergii Gottsche ” ( PC). — Prov. Antananarivo • Angavokely, I.1978, Tixier 11111, 11848 ( BR); Analamanga, Angavokely Forest, I.2011, Reeb 11 M140 , 11 M152 ( PC); Ankaratra, Manjakatompo Reserve, 1971, Cremers 1683, 1694, 1711, 1742, 1744 ( BR), Pócs 9481/ AH, Pócs 9481/D, 9481/ R ( EGR); Mandraka, II.1974, Onraedt 70 M2174 , 70 M2183 ( BR); Mandraka , Mt. Hantsambatonangavo , IX.1994, S. Orbán 9452/ CY ( EGR).— Prov. Antsiranana • Marojejy Nat. Park, Andampibe valley , III.1990, Pócs et al. 90111/ A ( EGR).— Prov. Fianarantsoa •

Nosiarivo, XI.1976, Tixier 9546 ( BR); Ambatofitorahana Forest S of Ambositra, Onraedt 70 M402 , 70M. 443, 70 M5321 , 70 M5325 , 70 M5321 , 70 M5379 ( BR); 33 km SSW of Ambositra, IX.1994, Pócs 9479/ C, 9479/ G ( EGR, GOET); Andringitra Nat. Park , trail to Pic Boby, IX.1994, Orbán 9458/ AD ( EGR); W tributary of Korokoro river , IX.1994, Pócs 9472/ A, 9472/ B, 9472/ C, 9472/ F, 9473/ BB, 9473/ BC, 9473/BE ( EGR); Ranomafana Nat. Park , Sahamalaotra Forest near Vohipara village , VII.2004, Pócs et al. 04120/BW ( EGR, GOET); near Ambatolahy, XI.1994, Pócs 9466/ S ( EGR); beyond W park boundary, Mt. Namatoana , Pócs & Tuba 04130/ K ( EGR). — Prov. Toamasina • East of Beforono, 600 m, III.1970, Cremers 70 M8061 ( BR); W coast of Masoala Peninsula, S of Ambanizana village, IX.1994, Pócs 9446/ AD, 9446/GQ, 9449/ H ( EGR); Andasibe-Mantadia Nat. Park , III.1990, Pócs et al. 90103/ AL, 90104/AB, 90105/D ( EGR), 9016/AG ( EGR, GOET); X.1994, Pócs 9485/ B ( EGR) .

DISTRIBUTION AND HABITAT. — Widespread in tropical and southern Africa. In Madagascar on bark, rock, soil and rotten wood in humid to subhumid evergreen forests from sea level to 2150 m.

DESCRIPTION (see also Jones 1962; Vanden Berghen 1981; Wigginton 2004)

Plants c. 2-5 mm wide, to 5 cm long, very flaccid, dichotomous to irregularly pinnately branched, branches mostly terminal, basal branches sometimes intercalary, rhizome-like creeping shoot present. Mature stem leaves distant to contiguous to subimbricate, ventrad, obliquely to widely spreading, sometimes deflexed, asymmetrically ovate-oblong to ligulate or ovate-triangular, 1.5-3× longer than wide, widest in the lower third or middle, branch leaves not ampliate and not shouldered, ventral margin usually recurved in the lower half, older stem leaves ampliate or not ampliate; leaf margins unbordered, dorsal leaf margin entire, apex and ventral margin with 3-20 small to large triangular teeth, the tip cell of the teeth elongate, 2-4× longer than wide, often broken; leaf bases narrowly decurrent, dorsal base shortly to moderately decurrent, ventral base very shortly decurrent. Cells of branch leaves small, subrectangular and in rows, c. 14-20 µm wide in midleaf, c. 1.5× longer than wide, with small triangular or cordate trigones, on longer walls radiate and sometimes confluent; cells of older stem leaves larger and subisodiametrical, not in rows, 18-25 µm wide in midleaf, trigones larger and swollen, cells not forming a border; cells in the dorsal leaf base not conspicuously elongate, vitta-like area absent; cuticle smooth; oil bodies not observed. Underleaves lacking or very small. Androecia terminal or intercalary, with 4-12 pairs of bracts. Perianths campanulate, mouth with narow laciniae, base not stalked. Vegetative reproduction by caducous leaves.

NOTES

Plagiochila terebrans (sect. Vagae) is a very common and variable species that is distinguished by the flaccid, dichotomous to irregularly pinnate plants with mostly terminal branches and with distant to subimbricate, ovate-oblong to ligulate leaves that are not ampliate to somewhat ampliate in basal stem leaves. The leaf margins have 3-20 triangular teeth with an elongate tip cell (2-4× longer than wide) and rather shortly decurrent bases, and the leaf cells are relatively small (15-25 µm wide in midleaf). Branch leaf cells are smaller than stem leaf cells and more elongate, subrectangular, ± arranged in rows.

Plagiochila terebrans may be confused with P. pectinata , but latter species lacks terminal branches and has leaves usually more strongly ventrad. Plagiochila terebrans approaches the neotropical P. deflexirama Taylor and P. tamariscina Steph. ( Pócs 2006; Gradstein 2021), but branching in the latter two species is purely pinnate, not dichotomous, and caducous leaves are not produced.

Figures

FIG. 22. ― Plagiochila terebrans Nees & Mont.: A, habit; B, dried shoot showing leaves ventrad habit of leaves; C, D, shoots in dorsal view with terminal branches; E, shoot in ventral view, showing underleaf; F, underleaf; G, leaves; H, leaf apex; I, midleaf cells; J, female bracts and perianth. From Reeb CR11152 (PC). Scale bars: A, B, 5 mm; C, D, G, J, 1 mm; E, 0.5 mm; F, 0.1 mm; H, I, 0.05 mm.