Hymenophyllum subg. Sphaerocionium (C.Presl) C.Chr., Index Filic., Suppl.

Kessler, Michael & Smith, Alan R., 2017, Prodromus of a fern flora for Bolivia. X. Hymenophyllaceae, Phytotaxa 328 (3), pp. 201-226 : 211

Hymenophyllum subg. Sphaerocionium (C.Presl) C.Chr., Index Filic., Suppl. 3, 5. 1934.

= Sphaerocionium C.Presl , Hymenophyllaceae (Presl) 33, t. 4, f. B, t. 10, f. B–C. 1843 [Abh. Königl. Böhm. Ges. Wiss., ser. 5, 3: 125. 1843].

= Microtrichomanes (Mett. ex Prantl) Copel., Philipp. J. Sci. 67(1): 35–36. 1938.

Subg. Sphaerocionium includes the hairy species of Hymenophyllum . The hairs can be simple, forked, stellate, or even bistellate and are located on the margins and often on the veins and sometimes the blade surfaces. Depending on the species, they can be sparse or dense, even obscuring the blade surfaces. Segment margins are mostly entire, but some species have finely toothed margins. A group of species is characterized by bearing lamellae perpendicular to the veins. These lamellae may be hard to see, especially if obscured by hairs (which are best locally removed to see the lamellae). The rhizomes, as in other species of Hymenophyllum , are long-creeping and filiform; blades are variously dissected, from 1–3-pinnate, and lanceolate to ovate or subdeltate. Sori are borne at the tips of the ultimate segments and bivalvate, with entire lips; receptacles are included. The chromosome base number is x = 36.

Subg. Sphaerocionium comprises ca. 70 species, 60+ in the Neotropics ( Morton 1947), 24 in Bolivia (two recently described by Kessler et al. 2005), 4+ in Africa and islands of the Indian Ocean ( Roux 2001), and a few in Polynesia and Southeast Asia; two spp. occur in Hawaii ( Palmer 2003). The subgenus has sometimes been treated as a genus, e.g., by Copeland (1938), Pichi Sermolli (1977), Palmer (2003), and Roux (2001). However, it is nested within Hymenophyllum s.l. ( Hennequin et al. 2003), sister to the combined clade comprising subg. Hymenophyllum + subg. Mecodium + subg. Globosa (southern South America, Southeast Asia, and Polynesia) (as defined by Ebihara et al. 2006).