Arachniodes Blume, Enum. Pl. Javae

Kessler, Michael, Moran, Robbin C., Mickel, John T., Matos, Fernando B. & Smith, Alan R., 2018, Prodromus of a fern flora for Bolivia. XXXV. Dryopteridaceae, Phytotaxa 353 (1), pp. 448-450 : 448-450

Arachniodes Blume, Enum. Pl. Javae 2: 241. 1828.

Arachniodes is characterized by creeping rhizomes, 3- to 4-pinnate blades with free veins, and reniform indusia. The genus is most closely related to Polystichum and Dryopteris , but in Bolivia it is most easily confused with Lastreopsis and Triplophyllum ( Tectariaceae ), which have the costae on the penultimate segments raised adaxially and catadromous blades (vs. axes grooved adaxially and blades anadromous in Arachniodes ). A genus of about 50 species, mostly in the Himalayas and China, with a few species in Africa and the Americas ( Christensen 1920, Morton 1960, Tindale 1961). Recent phylogenetic work on dryopteroid ferns has shown that A. denticulata , a species occurring in Bolivia, belongs to Arachniodes s.s., whereas two other neotropical species currently placed in the genus, A. macrostegia (Hook.) R.M.Tryon & D.S.Conant (not in Bolivia) and A. ochropteroides , form a clade with Olfersia ( Moran & Labiak 2015) . They will be either combined under Olfersia or given a new genus name pending further systematic studies (R.C. Moran & P. Labiak unpubl. data).