Taxonomic Revision of Cyathea, Clade Hymenophyllopsis (Cyatheaceae)

We present a taxonomic revision of Cyathea, Glade Hymenophyllopsis, a monophyletic group restricted to the tepuis of the Guiana Shield, a region in northern South America. We recognize fifteen species, including four newly described here: C. indefinite, C. minima, C. pseudoctenitoides, and C. tatei. The main diagnostic characters for the species are: rhizome (symmetry and scales), lamina division (pinnatisect to 5-pinnate), pinnae (congested or sparse, recurverd to ascending), scales and/or hairs of the rachis (shape, size, margins), as well as the shape and margin of the indusium (bivalvate or cyatheoid, entire to deeply lacerate). An identification key, descriptions, taxonomic comments, illustrations, and geographical distribution maps for all recognized taxa are provided.