Parablechnum humbertii (Tardieu) S.Molino & Lafuente, 2022

Molino, Sonia, Lafuente, Irene, Rouhan, Germinal & Medina, Rafael, 2022, Morphological and molecular evidence reject conspecificity of Malagasy and Mascarene Parablechnum (Polypodiopsida, Blechnaceae), PhytoKeys 214, pp. 47-60 : 47

Parablechnum humbertii (Tardieu) S.Molino & Lafuente comb. nov.

Blechnum humbertii ≡ Blechnum humbertii Tardieu Mém. Inst. Sci. Madagascar, Sér. B, Biol. Vég. 6: 232, f.5, 1955; Blechnum montbrisonis C. Chr. var. Blechnum montbrisonis humbertii (Tardieu) Rakontondr. Adansonia, série 3, 35(2): 178, 2013. Parablechnum marginatum var. humbertii (Tardieu) Gasper & Salino Phytotaxa 275(3): 216, 2016.

Type.

Madagascar. ‘Vallée, mont Beondroka, au Nord de Maroambihy , sylve à Lichens, sur gneiss et quartzite’, no date, Humbert 23554 (Holotype: P00483200) .

Description.

Plants terrestrial; rhizomes erect or sub-erect, non-stoloniferous, with ovate-lanceolate scales with elongated apex, more or less filiform, concolorous, brownish, membranaceous, with entire margins, up to 20 mm long; fronds dimorphic, sterile fronds with petioles 20-30 cm long, dark brown at base, straw-greyish distally, smooth, grooved adaxially, with scales in basal zone decreasing in density distally, similar to those of rhizome, leaving a black scar after falling off; laminae 1-pinnate, elliptic-acuminate, up to 30 cm, sometimes longer, rachises light brown, smooth, grooved adaxially, scales similar to those of petiole but narrower, more abundant in the adaxial side, pinnae in up to 20 pairs, alternate or subopposite, slightly smaller at the base, lanceolate-oblong, stalked, becoming basiscopically adnate towards apex of the frond, 10 × 1.5 cm, base asymmetric, subcordate to truncated, apex long acuminate, margins serrate, with a conforming terminal pinnae similar to lateral ones; veinlet free, simple or 1-furcate, catadromous; fertile fronds longer than sterile and more erect, petioles similar to sterile fronds, laminae 30 cm long, sometimes longer, lanceolate-oblong, rachises similar to sterile fronds, pinnae usually in more pairs than in the sterile ones, linear, narrow, 12.0 × 0.2 cm, slightly broader-based, asymmetrical, cordate, apex long acuminate; aerophores present in both sterile and fertile fronds, tuberculiform, atropurpureus; hydathodes present in both sterile and fertile fronds, rounded or ovate; sori linear, continuous, forming coenosori on both sides of the costa; indusia linear, continuous, open towards the costa, dark brown, membranaceous, sometimes lacerate.