Didymoglossum rotundifolium (Bonap.) J.P.Roux

Ahamada H. Saïd, Sabine Hennequin, Germinal Rouhan & Jean-Yves Dubuisson, 2017, Disentangling the diversity and taxonomy of Hymenophyllaceae (Hymenophyllales, Polypodiidae) in the Comoros, European Journal of Taxonomy 313, pp. 1-53 : 19-20

Didymoglossum rotundifolium (Bonap.) J.P.Roux

Didymoglossum rotundifolium (Bonap.) J.P.Roux , Strelitzia 23: 42 (2009). – Trichomanes rotundifolium Bonap. , Notes ptéridologiques 9: 23 (1920a). – Type: Madagascar, Massif de Manongarivo, s.d., H.Perrier de la Bâthie 7735 (lectotype, here designated: hololecto-: P00482612!; isolecto-: P00477780!, P00482613!); Madagascar, Massif de Manongarivo, s.d., H.Perrier de la Bâthie 7442 p.p. (syn-: P00482611!).

Short description

Lithophytic or epiphytic; long-creeping filiform rhizomes, rootless and densely covered by dense black trichomes, bearing widely separated pending fronds; fronds sessile to subsessile, up to 0.7(–1) cm long, round to oblong, or ovate, entire with entire to undulate margins, with palmate to slightly pinnate venation, and false veins parallel to true veins in addition to a submarginal false vein; mostly a single terminal sorus per fertile frond, rarely more, and epitactic, campanulate with a slightly dilated mouth.

Global distribution

Madagascar, Comoros.

Distribution in Comoros

Anjouan, Mayotte, Mohéli.

Additional specimens examined

COMOROS: ANJOUAN, s. loc., 1875, J.M.Hildebrandt s.n. (P00347524). MAYOTTE, Massif de Mtsapéré, Maison de la Convalescence, 10 Nov. 2002, F.Rakotondrainibe et al. 6670 (P00311383); Mont Tchaourembo, 13 Nov. 2002, F.Rakotondrainibe et al. 6681 (P00311397). MOHÉLI, Chalet St Antoine, 5 Nov. 2008, M.Pignal et al. 3484 (P00684897).

Note

The sheet P00482612, included in the original material, consists of many individuals with several fertile fronds, and specimens are representative of the morphology of the species. Moreover, this sheet was probably intended to be the holotype, as indicated by the handwritten annotation ‘Original’ by Bonaparte. For all these reasons, P00482612 was selected as the lectotype specimen for T. rotundifolium .

Didymoglossum rotundifolium is the smallest Comorian Hymenophyllaceae species with sessile to subsessile, round to oblong, entire fronds (never lobed contrary to D. erosum ), and laminae up to 0.7–1 cm long (see Fig. 2D ).

Figures

Fig. 2. Illustration of representative descriptors and states used in the Xper database (see Appendix 1). A. Hymenophyllum hirsutum (L.) Sw., typical bilabiate sori (S) without a developed base, fully hairy lamina with pedunculated brown trichomes (see inset). B. Didymoglossum robinsonii (Hook. ex Baker) Copel., false veins (FV) parallel but not connected to true veins (TV) and marginal dark trichomes clustered here by 6 (see inset). C. Crepidomanes inopinatum (Pic. Serm.) J. P. Roux, typical trichomanoid sori (S) with a developed tubular base, lips are here dilated as a collar. D. Didymoglossum rotundifolium (Bonap.) J. P. Roux, false veins (FV) parallel but not connected to true veins (TV) and continuous submarginal false vein (smFV), here the one-cell thick lamina appears well translucent. E. Crepidomanes bipunctatum (Poir.) Copel., false veins more or less continuous and parallel to margins (mFV) and not connected to true veins (TV). F. Hymenophyllum sibthorpioides (Bory ex Willd.) Mett. ex Kuhn, bilabiate sori (S) with toothed margins. Photographs by A. H. Saïd.