Polytaenium Desv., Mém. Soc. Linn. Paris

Kessler, Michael, Smith, Alan R. & Prado, Jefferson, 2017, Prodromus of a fern flora for Bolivia. XXVII. Pteridaceae, Phytotaxa 332 (3), pp. 201-250 : 241

Polytaenium Desv., Mém. Soc. Linn. Paris 6: 174, 218. 1827.

= Anetium Splitg., Tijdschr. Nat. Geschied. 7: 395. 1840.

Blades elliptic to oblanceolate with the sporangia along reticulate veins. Radiovittaria and Vittaria have narrower, linear blades with sporangia in only two lines, one on each side of the midrib. Species included in Polytaenium were formerly placed in Antrophyum , now considered to the restricted to the Old World tropics. Polytaenium occurs only in the Neotropics and comprises about 10 species ( Schuettpelz et al. 2016); most species were treated by Benedict (1907, 1911), essentially with the same circumscription as used in this and other recent treatments, e.g., by Tryon (1964) and by Tryon & Stolze (1989) for Peru. In phylogenetic analyses, the genus is sister to the combined clade Ananthacorus + Scoliosorus + Vittaria s.s. ( Ruhfel et al. 2008; Schuettpelz et al. 2016); all four genera are primarily neotropical, with Vittaria extending into Africa.

Anetium , monotypic, with broader blades, sporangia also between the veins, and distant leaves, has recently been subsumed in Polytaenium by Schuettpelz et al. (2016); in the analyses by Ruhfel et al. (2008) and Schuettpelz et al. (2016), it is sister to other species Polytaenium . It was formerly recognized as distinct by its broad, (2–) 5–13 cm wide, fleshy to subsucculent blades with sporangia scattered over the entire blade surfaces, especially along veins, often forming reticulate patterns, and by the leaves spaced along the creeping rhizomes.