Polyphlebium diaphanum (Kunth) 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 : 38-40

25. Polyphlebium diaphanum (Kunth) Ebihara & Dubuisson ( Ebihara et al. 2006: 240), Fig. 18A, B

Trichomanes diaphanum Kunth (Humboldt et al. 1815 [1816]: 25). ≡ Vandenboschia diaphana (Kunth) Copel. ( Copeland 1938: 53). Type :— VENEZUELA. ‘ Temperatis Provinciae Venezuelae’ , without date, A. Humboldt & A. Bonpland s.n. (lectotype P, P00669210 !, here designated; isolectotype B, BW 20 0086870!, here designated, following the R. G. Stolze’s annotation of isotype on the sheet).

= Trichomanes borbonicum Bosch (van den Bosch 1861b: 158, 159). ≡ Vandenboschia borbonica (Bosch) G.Kunkel ( Kunkel 1963: 213). ≡ Crepidomanes borbonicum (Bosch) J.P.Roux ( Roux 2001: 45). ≡ Polyphlebium borbonicum (Bosch) Ebihara & Dubuisson ( Ebihara et al. 2006: 240). Type:— LA REUNION. ‘Hab. Ins. Borboniae’, without date, L.H. Boivin 908 (lectotype B, BW 20 0103881!, designated by Schelpe & Anthony (1986: 76); isolectotype P, P00065006!, here designated).

= Trichomanes brasiliense Desv. ( Desvaux 1827: 328, t. 7, f. 4). Type:— BRAZIL. ‘Habitat in Brasilia’, without date, without collector (lectotype P, P00624517!, here designated).

= Trichomanes eximium Kunze ex Sturm ( Sturm 1859: 271, Pl. 18, Fig. 2 ). Type:— VENEZUELA? Without locality, without date, Moritz 148 (not located). Note: The type is reported in Kunze (1847: 350), and has not been observed, but the Fig. 2 (in Pl. 18) in Sturm (1859) shows clearly a P. diaphanum , hence we accept here the synonymy.

= Trichomanes debile Bosch (van den Bosch 1861b: 154). ≡ Trichomanes pyxidiferum var. debile (Bosch) Sodiro ( Sodiro 1890: 290). Type:— VENEZUELA. Carabobo, 1846, Funck & Schlim 596 (isotype BR, BR0000006988135!, BR0000006987466!, BR0000006988128!, BR0000006987794!).

= Trichomanes hymenophylloides Bosch (van den Bosch 1863: 209), nom. nov. for Trichomanes leptophyllum Bosch (vand den Bosch 1858: 363), nom. illeg., non A.Cunn. ( Cunningham 1836: 368). ≡ Vandenboschia hymenophylloides (Bosch) Copel. ( Copeland 1938: 53). ≡ Polyphlebium hymenophylloides (Bosch) Ebihara & Dubuisson ( Ebihara et al. 2006: 240). Type:— SAINT VINCENT. Without locality, without date, L. Guilding s.n. (type GH, GH00022242!). Note: Trichomanes leptophyllum sensu Bosch actually corresponds to the illustration of Trichomanes pyxidiferum by Hooker & Greville (1831: pl. 206) based on specimens collected by L. Guilding in Saint Vincent Island and thus considered by van den Bosch as a distinct species, as discussed and confirmed later by Slosson (1915) (see also Ponce et al. 2017).

= Trichomanes tranninense Fée ( Fée 1869: 187, t. 69, f. 1). Type:— BRAZIL. Rio de Janeiro, Macaé, 19 May 1868, A. Glaziou 2251 (holotype P, P00624521 !; isotype BR0000013094973 !).

= Trichomanes goetzei Hieron. ( Hieronymus 1900: 339). Type :— TANZANIA. Uluguru Gebirge, 22 November 1898, W. Goetze 194 (holotype B, BW 20 0093147!; isotype BM).

= Trichomanes eximium Kunze ex Sturm var. crispulum Rosenst. ( Rosenstock 1924: 89). Type:— BRAZIL. Rio de Janeiro,Organ mountains, Est, August 1915, P. von Luetzelburg 6196 (lectotype US, US 00512793!, designated by Lellinger (1977: 732); isolectotype M).

= Trichomanes pyxidiferum L. var. organense Rosenst. ( Rosenstock 1924: 89). Type:— BRAZIL. Rio de Janeiro, Serra dos Orgaos, 1910, P. von Luetzelburg 92 (lectotype S, S06-1221 !, here designated; isolectotypes M; NY, NY 00144725 !) ; BRAZIL. Rio de Janeiro, Serra dos Orgaos, 1910, P. von Luetzelburg 93 (remaining syntype M) .

= Trichomanes pyxidiferum L. f. gracile Rosenst. ( Rosenstock 1924: 90). Type:— BRAZIL. Rio de Janeiro, Corcovado, 1910, P. von Luetzelburg 262 (lectotype NY, NY 00144726 !, here designated; isolectotype M) .

Short description—Epiphytic or lithophytic; long-creeping filiform rhizomes, bearing sparsely distributed roots and reddish-brown trichomes, and widely separated pending fronds; fronds stipitate, up to 17 cm long, more often less than 10 cm long, deltoid to ovate, pinnate-pinnatifid to bipinnate-pinnatifid, without false veins or folds; sori numerous, paratactic, twice or more longer than wide, cylindrical with slightly dilated mouth ( Fig. 18B ); receptacle short to long-exerted.

Global distribution—Pantropical (see note).

Current distribution in Mascarenes— La Réunion.

Ecology—Epiphytic on tree-trunks or lithophytic on wet rocks in lowland to montane rainforests and high elevations (550–2,100 m).

Specimens examined— LA RÉUNION. Without locality, without date, J. M. C. Richard s.n. ( P01330947 ) ; Bélouve , October 1882, sine collector ( P01330933 ) ; Bébour , March 1969, T. Cadet 2099 ( P01330937 ) ; Cirque de Takamaka , January 1972, T. Cadet 3395 ( P01330939 ) ; Petite Plaine des Palmistes , January 1973, T. Cadet 4004 ( P01330941 ) ; Bébour , April 1999, J.- Y. Dubuisson HR-1999-22 ( P), HR-1999-31 ( P) .

Note—In local floras (e.g. Tardieu-Blot 1951, 2008; Grangaud 2010), this species is named P. borbonicum and considered as such to be restricted to tropical Africa and the western Indian Ocean. Ebihara et al. (2009) suggested that P. borbonicum should be included into a pantropical complex associating populations from the Pacific and neotropics. Ponce et al. (2017) clearly showed that the La Réunion specimens are phylogenetically imbedded into a robust clade with neotropical P. diaphanum (and P. hymenophylloides considered as synonym). Furthermore, there is no clear morphological character that could allow precisely distinguishing all the specimens belonging to P. borbonicum , P. diaphanum , and P. hymenophylloides . We thus adopt here the taxonomic treatment of Ponce et al. (2017) considering P. diaphanum as a widespread pantropical species including P. borbonicum .

Genus Vandenboschia Copel. ( Copeland 1938: 51)

Figures

FIGURE 2. Wet Mascarenan ecosystems. A. Lowland windward rainforest dominated by Sapotaceae trees, showing the understory with numerous low epiphytic and terrestrial free-sporing plants (liverworts, mosses, ferns, lycopods and spikemosses) and a few herbaceous angiosperms (especially orchids) (La Réunion, ‘Mare Longue’ forest, ~450 m). B. Montane rainforest dominated by Dombeyoideae (Malvaceae) trees and Alsophila spp. tree-ferns (Cyatheaceae) as emergents from the canopy (La Réunion, ‘Cassé de Takamaka, Bébour’, 1,100–1,200 m). C. Montane ericoid thickets (La Réunion, ‘Enclos du Piton de la Fournaise’, ~2,200 m). (Photographs. A, C: C. Chaussidon; B: J.-M. Tamon).

FIGURE 18. A. Polyphlebium diaphanum (Kunth) Ebihara & Dubuisson, as epiphyte (La Réunion, ‘Forêt de Bon Accueil, Les Makes’). B. P. diaphanum, detail of a frond and sori. C. Vandenboschia gigantea (Bory ex Willd.) Pic.Serm., climbing on a tree trunk (La Réunion, ‘Mare Longue’). D. V. gigantea, terrestrial parts (La Réunion, ‘Grand Etang’). E. V. gigantea, detail of a long-creeping climbing rhizome (photographs.A: L. Bauret; B–E: J.-Y. Dubuisson).