Synopsis of the genus Acianthera Scheidw. (Orchidaceae) in Rio Grande do Sul, Brazil

Abstract

The genus Acianthera Scheidw. (Orchidaceae) has been reestablished on the basis of phylogenetic analysis, which has demonstrated that Pleurothallis R.Br. is not monophyletic. The species of Acianthera have two pollinia, terminal inflorescences, and ramicauls devoid of an annulus. These characteristics, however, are not unique to the genus. This article is a taxonomic synopsis of Acianthera in the state of Rio Grande do Sul, Southern Brazil. Twenty-four species have been found, all predominantly epiphytic. One species, A. dutrae (Pabst) C.N. Gonç. & Waechter, proved to be endemic in the studied area. A key to species is presented. Each species is discussed and distribution data are provided. Illustrations of selected species are also presented.