Taxonomic study of the fern genera Abrodictyum C. Presl and Trichomanes L. (Hymenophyllaceae, Polypodiidae) in the western Indian Ocean, and description of a new Abrodictyum species for Madagascar Author Dubuisson, Jean-Yves Author Bauret, Lucie Institut Systématique Evolution Biodiversité (ISYEB), Sorbonne Universités, MNHN, CNRS, UPMC, EPHE, Herbier National, 57 rue Cuvier, CP 39, 75005 Paris, France. Author Grall, Aurelie Royal Botanic Gardens, Kew, Richmond, Surrey, TW 9 3 AE, United Kingdom. Author Senterre, Bruno Island Biodiversity & Conservation Centre, associated with the University of Seychelles, Anse Royale, Mahé, P. O. Box 1348, Seychelles. & Evolutionary Biology & Ecology - CP 160 / 12, Université Libre de Bruxelles, 50 Av. F. Roosevelt, 1050 Bruxelles, Belgium. Author Said, Ahamada H. Institut Systématique Evolution Biodiversité (ISYEB), Sorbonne Universités, MNHN, CNRS, UPMC, EPHE, Herbier National, 57 rue Cuvier, CP 39, 75005 Paris, France. Author Pynee, Kersley The Mauritius Herbarium, Agricultural Services, Agronomy Division, Ministry of Agro-Industry and Food Security, Réduit, Mauritius. Author Ebihara, Atsushi Department of Botany, National Museum of Nature and Science, 4 - 1 - 1 Amakubo, Tsukuba, 305 - 0005, Japan Author Hennequin, Sabine text Phytotaxa 2017 2017-11-10 327 3 201 222 http://dx.doi.org/10.11646/phytotaxa.327.3.1 journal article 10.11646/phytotaxa.327.3.1 1179-3163 13723223 Trichomanes cupressoides Desv. (1827: 330) . ≡ Selenodesmium cupressoides (Desv.) Copel. (1938: 81) . ≡ Abrodictyum cupressoides (Desv.) Ebihara & Dubuisson (2006: 244) . Type:— SEYCHELLES . “Habitat in insulis Séchelles”, without date, without collector ( holotype P, P00065002!). Terrestrial ferns. Rhizomes short, erect, 0.5–1.2 cm in diameter, bearing long tufted erect red-brown trichomes, and numerous robust roots. Fronds clustered, erect; stipes 8–16 cm long, wingless and canaliculate, bearing occasional trichomes identical to those present on rhizomes, or concentrated on the stipe bases; rachises slightly winged on their upper part and with similar trichomes as the stipes and rhizomes. Laminae 12.0–18.0 × 5.5–11.0 cm, triangular to deltoid, tri-pinnate-pinnatifid; pinnae 3.5–7.0 × 1.0–3.0 cm, sub-horizontal to oblique, basally sub-opposite then alternate, triangular to linear; pinnules bi-pinnatifid, ovate to linear, with decurrent lamina along the second order rachises; ultimate segments fused at least at their third length, mostly with capillary apices; venation pinnate and anadromous. Sori paratactic, on acroscopic basal-most segments of proximal pinnules, 1.2–2.0 × 0.6–0.8 mm , 1–3 per pinnule, up to 26 per pinna, free, cylindrical, more often slightly bilabiate with a dilated mouth; receptacle short to long-exerted. Distribution and habitat: —Endemic to the Seychelles ( Mahé and Silhouette islands), terrestrial in the understory of rainforests from sea level to the highest summits (up to 800 m ) but restricted to wet and shady micro-habitats in the lowland belt, especially at the lower edge of granite boulders (receiving the shade and water catchment of the large rocks). It is more widespread in the understory of lower montane forests, above 500 m ( Table 1 ). Specimens examined :— SEYCHELLES . Mahé Island: without date, Awmack 393, 524 (SEY); Mare aux Cochons, August 1895 , Brauer 3, 4 (P01627088); Séchelles et 3 frères, without date, Commerson? s.n. (P00065003); Jasmin Peak, January 1970 , Fosberg 51965 (P01472766); without date, Fosberg & Mason 52003 (SEY); Morne Blanc, November 1982 , Friedmann 4370 (P01214236); without date, L. Humblot 1882 (P01427008, P01427009); Casse Dent, November 2006 , T. Janssen & Mougal 3225 (SEY, P00591042); Souvenir, November 1961 , Jeffrey 515 (P01627093, SEY); Morel 45 (SEY); Ravins derrière la ville de Mahé, February 1840 , Pervillé? s.n . (P01472767); 1841, Pervillé? s.n. (P01472768, P01627089); Congo Rouge, May 1970 , Procter 3923 (P01627091, SEY); Casse Dent, sur la route de Congo Rouge, March 2003 , G. Rouhan et al. 135 (P00696126); January 1876 , without collector. (P01627094); 1903, without collector. (P01627092); without date, Senterre & Malbrook 4995 (SEY). Silhouette Island: Mont “Corgate”, November 1973 , Bernardi 14647 (P01627090). Note:— The specimen P00065003 was first registered as isotype of Trichomanes cupressoides but it is from a different collection.