Abrodictyum franceae Bauret & Dubuisson, 2016

Dubuisson, Jean-Yves, Bauret, Lucie, Grall, Aurelie, Li, Tian, Ebihara, Atsushi & Hennequin, Sabine, 2016, Discussion on the taxonomy of African fern Abrodictyum rigidum (Sw.) Ebihara & Dubuisson and description of two new Abrodictyum C. Presl species (Hymenophyllaceae, Polypodiidae) for the Afro-Malagasy region, Phytotaxa 284 (3), pp. 151-168 : 163-164

Abrodictyum franceae Bauret & Dubuisson , sp. nov., Fig. 7

Plants distinct from other terrestrial Malagasy Abrodictyum spp. by combining linear uni-veined ultimate segments with acute to rounded ends, lamina always more than 4–5 cells wide on each side of the veins, frond division not exceeding bipinnate-pinnatifid and appearing mostly crisped/curled in the wild (vs. flat/plane in the other species).

TYPE:– MADAGASCAR. Antsiranana: Réserve Spéciale de Manongarivo, le long d’un petit cours d’eau large de 1–1.5 m, 29 September 2004, G. Rouhan et al. 267 (holotype P, P 00749196).

Terrestrial ferns. Rhizomes short, erect, 0.5–1.0(–1.5) cm in diameter, bearing long tufted erect red-brown more or less catenate pluricellular trichomes, especially densely covering apex, and numerous robust roots. Fronds clustered, erect; stipes 2.5–9.5(–13.0) cm, canaliculate, wingless or with a thin wing only at their upper part, bearing numerous scattered trichomes identical to those present on rhizomes; rachises and main pinna axes with trichomes similar to those on the stipes and rhizomes. Laminae (8.5–)11.0–16.0(–20.0) × 3.0–6.0(–8.5) cm, lanceolate with truncated base and mostly linear apex, not more than bipinnate-pinnatifid, light green and translucent, mostly more or less crisped or curled in the wild; pinnae 1.5–4.5 × 0.5–2.2 cm, sub-horizontal to oblique, basally sub-opposite then alternate, lanceolate, or triangular to linear; pinnules pinnatifid, lanceolate to linear, with slightly decurrent lamina along the second order rachises; ultimate segments 0.3–0.5 mm wide, linear and uni-veined with acute to rounded ends, the veins not reaching the margin; venation pinnate and anadromous; laminar cells thick-walled with walls up to 10 μm thick and more or less wavy, tetragonal to pentagonal, mostly isodiametric. Sori paratactic, mostly on acroscopic basal-most segments of proximal pinnules, 1.0–1.5 × 0.6–0.9 mm, 1–3(–6) per pinnule, up to 25 per pinna, free with a thin full longitudinal wing on both margins, conical to campanulate, with a slightly to well dilated mouth; receptacle short to long-exerted.

Distribution and habitat: —Endemic to Madagascar, terrestrial in the understory of rainforests, usually near streams, at middle to high elevations (500–1,700 m).

Etymology: —The specific epithet is dedicated to France Rakotondrainibe (MNHN Paris), specialist of Malagasy ferns diversity and ecology, who significantly contributed to renew and improve pteridology in Madagascar.

Specimens examined: see Appendix 1.

Figures

FIGURE 7. Abrodictyum franceae Bauret & Dubuisson, sp. nov. (G. Rouhan et al. 267, holotype P00749196).A. Habitus; B. Detail of a pinna with sori; C. Detail of indusium; D. Detail of laminar cells, the arrow shows the margin.