Crepidomanes trinerve (Baker) Dubuisson & Ebihara

Dubuisson, Jean-Yves, Pechon, Timothée Le, Bauret, Lucie, Rouhan, Germinal, Reeb, Catherine, Boucheron-Dubuisson, Elodie, Selosse, Marc-André, Chaussidon, Cécile, Dajoz, Isabelle, Pynee, Kersley, Grangaud, Edmond, Robert, Yannis, Tamon, Jean- Maurice & Hennequin, Sabine, 2018, Disentangling the diversity and taxonomy of Hymenophyllaceae (Hymenophyllales, Polypodiidae) in the Mascarene archipelago, with ecological implications, Phytotaxa 375 (1), pp. 1-58 : 23-24

11. Crepidomanes trinerve (Baker) Dubuisson & Ebihara ( Dubuisson et al. 2013: 187), Fig. 11

Trichomanes trinerve Baker (1877: 465) . Type:— MAURITIUS. Without locality, without date, H. Barkly and A.M. Barkly s.n. (holotype K, K000228373!).

= Trichomanes ambongoense Bonap. ( Bonaparte 1920a: 13, 14). Type:— MADAGASCAR. ‘ Ambongo’, without date, H. Perrier de la Bâthie 7501 (lectotype P, P00466414 !; isolectotype P, P00466408 !, designated by Dubuisson et al. 2013); H. Perrier de la Bâthie 7769 (paralectotype P, P00466412 !, P00466413 !) ; H. Perrier de la Bâthie 7770 (paralectotype P, P00466410 !, P00466411 !) ; H. Perrier de la Bâthie 7771 (paralectotype P, P00466409 !, P00482601 !) .

= Trichomanes angustilaciniatum Bonap. (Bonaparte 1925: 11, 12). Type :— MADAGASCAR. ‘ Massif d’Andringitra’, April 1921, H. Perrier de la Bâthie 13756 (lectotype P, P00482604 !, here designated; isolectotype P, P00482603 !).

Short description—Lithophytic, less often epiphytic; long-creeping filiform rhizomes, rootless and densely covered by dense black trichomes, bearing widely separated pending fronds; fronds with slightly winged stipes, up to 3.5(–5) cm long, flabellate to obovate, palmatisect to digitate, less often pinnatifid, with always, when dry, folds parallel to veins; sori few, paratactic, campanulate with a well dilated mouth; receptacle usually included to slightly exerted.

Global distribution—Western Indian Ocean (incl. Comores; excl. Seychelles).

Current distribution in Mascarenes— La Réunion, Mauritius.

Ecology—Usually lithophytic on shaded, wet rocks in lowland rainforests at low elevations (500–800 m) and one population reported in a wet ravine on the western side of La Réunion in remnants of semi-dry forest. Because of the easy confusion with the other dwarf Crepidomanes species, additional field investigations are required to assess the distribution of this species in the Mascarenes.

Specimens examined— MAURITIUS. Montagne du Corps de Garde, November 1973, M. J. E. Coode 4103 ( MAU 0012276 ) ; Rivière des Galets , D. Lorence 1483 ( MAU 0012277 ) ; Montagne des Deux Mamelles , January 1972, D. Lorence s.n. ( MAU 0012278 ) ; Tamarind Falls , March 1975, D. Lorence 1133 ( MAU 0012279 ) ; Vacoas , 1867, C. Meller s.n. ( MAU 0012280 ) ; Without locality, without date, sine collector ( MAU 0012281 ) .

— LA RÉUNION. Les Canots, September 2009, J.-M. Tamon 113 (private collection).

Note—As reported in Dubuisson et al. (2013) and Saïd et al. (2017), Crepidomanes trinerve is often confused with C. minutum , the first being even considered as a synonym of C. minutum by Roux (2009). Both taxa are nevertheless clearly distinct based on the stipe, which is terete and wingless in C. minutum (see Fig. 10C–G ) and slightly but always winged in C. trinerve , in addition to some sorus features ( Dubuisson et al. 2013). Crepidomanes trinerve was initially considered absent on La Réunion and the La Réunion specimens of C. trinerve were considered to be C. inopinatum var. tamonii ( Dubuisson et al. 2014) . However, C. trinerve specimens were finally and recently discovered and clearly identified on La Réunion at ‘Les Canots’ locality. The species is known on Mauritius from the type and a few herbarium specimens (see Dubuisson et al. 2013).

Genus Didymoglossum Desv. ( Desvaux 1827: 330)

Figures

FIGURE 10. A. Crepidomanes inopinatum (Pic.Serm.) J.P.Roux var. inopinatum, as lithophyte (La Réunion, ‘Petite Plaine’). B. C. inopinatum var. tamonii Y.Robert & Dubuisson, habit (Y. Robert 913, P02433924). C. C. minutum (Blume) K.Iwats. var. minutum, as epiphyte (La Réunion, ‘Bébour’). D. C. minutum var. minutum, frond with long terete wingless stipe. E. C. minutum var. minutum, showing stipe proliferation, scale = 1 cm (from Madagascar, F. Rakotondrainibe 3698, P00085267). F. C. minutum var. mascarenense Pynee & Dubuisson, as epiphyte (La Réunion, ‘Grand Etang’). G. C. minutum var. mascarenense, detail of fronds with short stipes. (photographs. A: J.-Y. Dubuisson; C–D: C. Chaussidon; F–G: E. Grangaud).

FIGURE 11. Crepidomanes trinerve (Baker) Dubuisson & Ebihara. A. As lithophyte in a wet ravine of the western side of La Réunion (‘Les Canots’; photograph by J.-M. Tamon). B. Habit (from Comores, F. Rakotondrainibe 6651, P00310478; modified from Dubuisson et al. 2013).