Hymenophyllum capillare Desv.

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 : 30-31

18. Hymenophyllum capillare Desv. ( Desvaux 1827: 333), Fig. 15A, B

≡ Sphaerocionium capillare (Desv.) Copel. ( Copeland 1938: 33). Type:— LA REUNION. ‘Pend aux arbres dans les forets humides Ile Bourbon’, without date, without collector (lectotype P, P00065016!, here designated). Note: The reference both in the protologue and on the sheet to ‘Tristan da Cunha’ (label handwritten by Desvaux in the left bottom corner) and to ‘ Trich. hirsutum Du Pet. -Th.’ (handwritten by Thouars) supports the type status of the specimen here selected as lectotype. However, considering the handwritten label by J.M.C. Richard (Director of the Botanical Garden in La Réunion from 1831) on the left of the plant, the origin of the plant might be ambiguous, as the plant is here said from ‘Bourbon’ (La Réunion). In fact, as detailed by Christensen (1940) and, later supported by Morton (1973), the annotation by Desvaux mentioning ‘Insula Tristan da Cunha’ is erroneous because H. capillare does not occur on this island. Thus, the Bourbon annotation makes sense even if it seems to have been later crossed out on the sheet.

= Hymenophyllum pendulum Bory (Bory 1834: 81, 82, pl. 8, fig. 2). ≡ Sphaerocionium pendulum (Bory) C.Presl ( Presl 1843: 34). Type:—‘Des forêts de Mascareigne’, an X [1801–1802], J.B.G.M. Bory de St.-Vincent s.n. (lectotype P, P00477830!, here designated in accordance with the lectotypification proposed by R. Pichi-Sermolli directly on the sheet). Note: the lectotypification is supported by the strong resemblance between the illustration in Bory (1834) and the Bory’s specimen.

Short description—Epiphytic; long-creeping filiform rhizomes, bearing sparsely distributed roots and long reddish-brown trichomes, and widely separated pending fronds; fronds with usually wingless stipes and rachises, up to 40 cm long, linear to narrowly oblong, bi-pinnate-pinnatifid, less often tripinnate, densely hairy with reddish-brown, stellate, non-pedonculated trichomes on rachises, veins, on both sides of laminae and margins; numerous sori, paratactic, bilabiate without a developed base nor lateral veinlets, but with hairy margins; receptacle short and included.

Global distribution—Central Africa to western Indian Ocean.

Current distribution in Mascarenes— La Réunion.

Ecology—Epiphytic on tree-trunks in lowland to montane rainforests up to the tree-line (400–2,000 m).

Representative specimens examined— LA RÉUNION. Without locality, without date, J. B. G. M. Bory de StVincent s.n. ( P00477830 ) ; GR de la Roche écrite, January 2002, Pignal et al. 1951 ( P00239563 ) ; Bébour , without date, T. Cadet 540bis ( P01328009 ) ; Montagne Saint Denis , September 1968, T. Cadet 1511 ( P01328014 ) ; Plaine des Chicots , November 1970, T. Cadet 2892 ( P01328020 ) .

Note— Hymenophyllum capillare , at least the typical form, is easily distinguished from other Mascarenan hairy Sphaerocionium species by its linear to narrowly oblong fronds with wingless stipes (vs. winged for H. hirsutum ) and rachises (vs. winged for both H. hirsutum and H. hygrometricum , at least at its upper part for the latter species).

Figures

FIGURE 15. A. Hymenophyllum capillare Desv., typical form, as epiphyte (La Réunion, ‘Forêt de Bon Accueil, Les Makes’). B. H. capillare, typical form, detail of fronds. C. H. capillare f. nanum Hennequin & Dubuisson, f. nov., as epiphyte (La Réunion, ‘Pitons Mare à Boue’). D. H. capillare f. nanum, habit, type individual, scale = 0.5 cm (La Réunion, ‘Forêt de Bon Accueil, Les Makes’, J.-Y. Dubuisson & L. Bauret HR 2016-10, P). E. H. digitatum (Sw.) Forsberg, as epiphyte (La Réunion, ‘Forêt de Bon Accueil, Les Makes’). F. H. digitatum, detail of laminar margin showing minute dark trichomes. G. H. digitatum, detail of fronds and sori with tubular bases (s) (photographs.A–B: L. Bauret; C–G: J.-Y. Dubuisson).