Resurrection and emended description of Gastrodia foetida (Orchidaceae)

Abstract

This paper presents a re-evaluation of the taxonomic identity of Gastrodia foetida based on molecular and morphological data. The taxon was described from Iriomote Island, Ryukyu Islands, Japan, and has often been treated as a synonym of G. nipponica from Wakayama Prefecture, Honshu, Japan. In contrast, we showed that the genetic divergence between G. foetida and G. nipponica is much more significant than that between G. foetida and G. takeshimensis. Additionally, G. foetida can be distinguished from G. nipponica by a few morphological traits, particularly a more dilated column toward a little below the middle. Therefore, we propose that G. foetida is recognized as a distinct species based primarily on molecular phylogenetic evidence followed by morphological evidence. Our investigation strongly suggested that these species exhibit distinct geographic separation: G. nipponica is restricted in mainland Japan (north of the Ryukyu Islands), whereas G. foetida is mainly distributed on the more southern areas (the Ryukyu Islands and possibly Taiwan).