Didymoglossum lorencei (Tardieu) Ebihara & Dubuisson

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 : 26-27

14. Didymoglossum lorencei (Tardieu) Ebihara & Dubuisson ( Ebihara et al. 2006: 236), Fig. 12B–D

Trichomanes lorencei Tardieu ( Tardieu-Blot 1977: 147, pl. 1, t. 7–13). Type:— MAURITIUS. Valley Cascade, March 1975, D. Lorence 1175 (holotype P, P00477828!).

Short description—Epiphytic or lithophytic; long-creeping filiform rhizomes, rootless and densely covered by dense black trichomes, bearing widely separated pending fronds; fronds sessile to sub-sessile, up to 1.5 cm long, oblong to obovate, entire with entire to undulate margins, with palmate venation and false veins parallel to true veins, hairy with dark, not pedonculated trichomes on lamina margins ( Fig. 12D ); a single terminal sorus per fertile frond, cylindrical with lips usually parallel and with brown margins; receptacle usually covered by the lips..

Global distribution—Western Indian Ocean (excl. Seychelles).

Current distribution in Mascarenes— La Réunion, Mauritius.

Ecology—Epiphytic on tree-trunks or lithophytic on shaded, wet rocks in lowland rainforests (150–550 m) and also one reported population in a wet ravine of the western side of La Réunion in remnants of semi-dry forest.

Specimens examined— MAURITIUS. Vallée de Ferney, October 2010, S. Hennequin et al. 400 (MAU, P02432468)

— LA RÉUNION. Brûlé de Takamaka, June 2006, E. Grangaud 1752 (P01627307), October 2010, S. Hennequin et al. 309 (P02432362).

Note—This rare dwarf species can be confused in the wild with D. barklyanum , but clearly shows false veins parallel to true veins, absent in the latter species.

Genus Hymenophyllum Sm. (Smith 1793: 418)

Subgenus Hymenophyllum

Figures

FIGURE 12. A. Didymoglossum barklyanum (Baker) J.P.Roux, as lithophyte (Mauritius, ‘Vallée d’Osterlog’). B. D. lorencei (Tardieu) Ebihara & Dubuisson, as lithophyte (La Réunion, ‘Grand Etang’). C. D. lorencei, detail of frond with marginal trichomes (photographs. A–C: J.-Y. Dubuisson; D: J.-M. Tamon).