Disentangling the diversity and taxonomy of Hymenophyllaceae (Hymenophyllales, Polypodiidae) in the Mascarene archipelago, with ecological implications Author Dubuisson, Jean-Yves Institut de Systématique, Evolution, Biodiversité (ISYEB), Sorbonne Université - SU, MNHN, CNRS, EPHE, 57 rue Cuvier, CP 48, 75005 Paris, France. Author Pechon, Timothée Le Institut de Systématique, Evolution, Biodiversité (ISYEB), Sorbonne Université - SU, MNHN, CNRS, EPHE, 57 rue Cuvier, CP 48, 75005 Paris, France. & Botanic Garden Meise, Nieuwelaan 38, 1860 Meise, Belgium Author Bauret, Lucie Institut de Systématique, Evolution, Biodiversité (ISYEB), Sorbonne Université - SU, MNHN, CNRS, EPHE, 57 rue Cuvier, CP 48, 75005 Paris, France. & Institut de Systématique, Evolution, Biodiversité (ISYEB), Muséum national d’Histoire naturelle, CNRS, Sorbonne Université, EPHE, 57 rue Cuvier, CP 39, 75005 Paris, France. Author Rouhan, Germinal Institut de Systématique, Evolution, Biodiversité (ISYEB), Muséum national d’Histoire naturelle, CNRS, Sorbonne Université, EPHE, 57 rue Cuvier, CP 39, 75005 Paris, France. Author Reeb, Catherine Institut de Systématique, Evolution, Biodiversité (ISYEB), Sorbonne Université - SU, MNHN, CNRS, EPHE, 57 rue Cuvier, CP 48, 75005 Paris, France. Author Boucheron-Dubuisson, Elodie Institut de Systématique, Evolution, Biodiversité (ISYEB), Sorbonne Université - SU, MNHN, CNRS, EPHE, 57 rue Cuvier, CP 48, 75005 Paris, France. Author Selosse, Marc-André Institut de Systématique, Evolution, Biodiversité (ISYEB), Muséum national d’Histoire naturelle, CNRS, Sorbonne Université, EPHE, 57 rue Cuvier, CP 39, 75005 Paris, France. & Department of Plant Taxonomy and Nature Conservation, University of Gdansk, Wita Stwosza 59, 80 - 308 Gdansk, Poland. Author Chaussidon, Cécile Institut de Systématique, Evolution, Biodiversité (ISYEB), Sorbonne Université - SU, MNHN, CNRS, EPHE, 57 rue Cuvier, CP 48, 75005 Paris, France. Author Dajoz, Isabelle Institut d’Ecologie et des Sciences de l’Environnement de Paris (iEES), Univ. Paris Diderot, Sorbonne Université, CNRS, INRA, IRD, UPEC, 4 place Jussieu, CC 237, 75252 Paris cedex 05, France. Author Pynee, Kersley The Mauritius Herbarium, Agricultural Services, Agronomy Division, Ministry of Agro-Industry and Food Security, Réduit, Mauritius. Author Grangaud, Edmond 21, les Cytises - Terre-Sainte, 97410 Saint-Pierre, La Réunion, France. Author Robert, Yannis Association des Naturalistes de Bourbon, 18 rue des capucines, 97431 Plaine des Palmistes, La Réunion, France. Author Tamon, Jean- Maurice Association des Naturalistes de Bourbon, 18 rue des capucines, 97431 Plaine des Palmistes, La Réunion, France. Author Hennequin, Sabine Institut de Systématique, Evolution, Biodiversité (ISYEB), Sorbonne Université - SU, MNHN, CNRS, EPHE, 57 rue Cuvier, CP 48, 75005 Paris, France. text Phytotaxa 2018 2018-11-09 375 1 1 58 http://dx.doi.org/10.11646/phytotaxa.375.1.1 journal article 10.11646/phytotaxa.375.1.1 1179-3163 13727979 15. Didymoglossum cuspidatum (Willd.) Ebihara & Dubuisson ( Ebihara et al. 2006: 236 ), Fig. 13 Trichomanes cuspidatum Willd. (Willdenow 1810: 499). ≡ Microgonium cuspidatum (Willd.) C.Presl ( Presl 1843: 20 ). Type :— MAURITIUS . ‘ Grandes forêts des Iles de France’ , without date, J.B.G.M. Bory de Saint-Vincent s.n. ( lectotype B, BW 20 205010!, here designated; isolectotype P, P00612305 !). = Trichomanes bojeri Hook. & Grev. ( Hooker & Greville 1829 : pl. 155). Type:—‘In sylvis umbrosis, ad arborum truncos, in Insula Mauritii’, without date, D. Bojer s.n. ( holotype K, K000435677!). Short description—Epiphytic or lithophytic; long-creeping filiform rhizomes, rootless and densely covered by dense black trichomes, bearing widely separated pending fronds; fronds sub-sessile or well stipitate, up to 6 cm long, usually less than 3–4 cm long, quite variable and highly polymorphic, glabrous, entire with entire to mostly sinuate margins, to slightly lobed, sub-circular to narrowly deltoid to lanceolate, sometimes linear, with palmate venation, false veins parallel to true veins in addition to a continuous sub-marginal false vein ( Fig. 13E ); 1–10 sori per fertile frond, cylindrical to narrowly campanulate with a slightly dilated mouth and usually immersed in apical distinct lobes when numerous; receptacle short to long-exerted. Global distribution—Western Indian Ocean (excl. Comores ). Current distribution in Mascarenes— La Réunion , Mauritius , Rodrigues . Ecology—Opportunistic, epiphytic and lithophytic on various substrates in the understory of rainforests and in wet ravines from low to middle elevations ( 0–1,300 m ). The species is usually abundant in lowland rainforests, but is rarer and mostly located in wet ravines in montane rainforests. This is the single Hymenophyllaceae species present on Rodrigues , in a single wet ravine. Specimens examined—‘Ile de Mascareigne’, without locality, 1831, C. Bélanger s.n. (P00612306). — MAURITIUS . Bel Ombre , October 2010 , S . Hennequin et al. 383 ( MAU 0008184 , P02432448 ) ; Fayence Mt. , December 2007 , K . Pynee et al. s.n. ( MAU 0008189 ) ; Rambouillet , April 2011 , K . Pynee s.n. ( MAU 0008209 ) ; Alma Hill , September 2012 , K . Pynee et al. s.n. ( MAU 0008224 ) ; Bar Le Duc , August 2011 , K . Pynee et al. s.n. ( MAU 0009100 ) ; Trou aux Cerfs , October 2015 , K . Pynee et al. s.n. ( MAU 0011483 ) ; Mare Longue , October 2010 , S . Hennequin et al. 361 ( MAU 0011513 , P02432425 ) . — LA RÉUNION . Without locality, without date, J . M . C . Richard 122 ( P00065001 ) ; Ilet Alcide , November 2004 , F . Rakotondrainibe et al. 6897 ( P00411902 ) . Note—This widespread species is readily distinguished from the other Didymoglossum species in Mascarenes by its glabrous fronds. Its distinctiveness outside the Mascarenes is discussed in Saïd et al. (2017) .