Polytaenium Desv.
Descripción
Rhizomes short-creeping, with decidedly clathrate scales; roots densely tomentose with abundant root hairs; fronds small; stipes short to absent; blades simple, linear to elliptic or oblanceolate, entire, glabrous; veins anastomosing to form 2–several series of areoles, without included veinlets; epidermis with linear idioblasts; sori linear, in 2–6(–8) lines parallel to the midvein or in shorter, irregular oblique lines, either on the surface or more commonly immersed in the lamina; indusia absent; paraphyses absent; spores yellow-hyaline or rarely green, tetrahedralglobose; x=60.A
Forma de vida
EpífitaA
Distribución
México (país) Nativo y no endémicoA
Categoría IUCN
No incluidaB
Categoría NOM-059-SEMARNAT-2010
No incluidaC
Discusión taxonómica
Polytaenium comprises 8–10 neotropical species, with four species occurring in Mexico. The genus is restricted to tropical and montane rain forest habitats throughout its range. Often, it has been subsumed under Antrophyum s.l., which in the restricted sense comprises about 20 species in Africa, south-central and southeastern Asia, and islands of the western Pacific (Polynesia). According to phylogenetic reconstruction done by Crane (1997), Antrophyum is sister to a predominantly New World clade comprising Polytaenium, Vittaria s.str., Ananthacorus, and Scoliosorus. Polytaenium and Antrophyum have historically been distinguished by the presence of a distinct, or at least proximally distinct, midrib in the former genus and the absence of a midrib in the latter. Species of Polytaenium lack paraphyses, and those of Antrophyum bear paraphyses. Polytaenium is distinguished from Vittaria by having more than one sorus on each side of the midrib, or by having continuous sori along the reticulate veins.
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