A Revised Infrageneric Classification of Old World Species of Dioscorea (Dioscoreaceae)

Abstract

Dioscorea (Dioscoreaceae), a morphologically diverse genus, consists of more than 600 species distributed worldwide. Recent molecular and morphological analyses allowed us to recognize two subgenera, Dioscorea and Helmia, and 19 Old World species groups (sections) in subgenus Helmia. In this paper we present a diagnostic key and taxonomic treatment for the subgenera and sections, including D. sect. Tamus (stat. nov.) and four new sections; Afroborderea, Perennia (validated here), Pseudoshannicorea and Pseudostenophora. Lectotype species for eleven sections; Enantiophyllum, Illigerastrum, Lasiophyton, Macrocarpaea, Macropoda, Madagascarienses, Orientali-asiaticae, Rhacodophyllum, Shannicorea, Stenophora and Syntepaleia, are also designated.