Dendrobium bigibbum (sect. Phalaenanthe) in Australia - analysis of diagnostic characters, review of taxa and a new classification

Dendrobium bigibbum Lindl. has a long confused history, with taxa variously described as separate species, subspecies, varieties and forms. This paper records morphological variation in 160 representative plants in north Queensland and Torres Strait. The distribution range is delineated. ITS-DNA results did not show significant differences between populations. The evidence supports a single species D. bigibbum Lindl. with three intergrading varieties: vars bigibbum, superbum and compactum. Some types have uncertain provenance, particularly D. phalaenopsis, which is reduced to synonymy under D. bigibbum var. superbum. A combination of characters can be used to identify varieties. A new combination of D. bigibbum var. compactum reduces D. phalaenopsis var. compactum to synonymy.