Taxonomic revision of Sobralia section Racemosae Brieger (Sobralieae, Orchidaceae)

Abstract

Sobralia Ruiz & Pav. is a large and morphologically diverse neotropical orchid genus. It can be divided into four sections and some informal groups of species based mainly on the inflorescence architecture. While most of the species have strongly abbreviated, compact raceme, the section Racemosae is characterized by an elongated inflorescence with distinct internodes between flowers. Although the group is well-defined and easily distinguishable in terms of morphology, its species are often similar to each other and may be easily misidentified. Identification is especially difficult when considering herbarium specimens. Here, a taxonomic revision of Sobralia section Racemosae is presented. Apart from particular species’ morphological characteristics, keys for identification, ecological data, and distribution maps are presented. Sobralia gambitana is described as a species new to science. A neotype for S. hoppii Schltr. is proposed.