Molecular phylogeny of the subgenus Holothuria (Selenkothuria) Deichmann, 1958 (Holothuroidea: Aspidochirotida)

The subgenus Selenkothuria comprises 12 species of tropical shallow water sea cucumbers that share morphological features, such as rods in the body wall and tube feet, modified tentacles for suspension feeding, and cryptic colours. The taxonomic status of this taxon has been controversial, but currently it is accepted as a subgenus of the genus Holothuria. Phylogenetic analyses of mitochondrial genes [cytochrome c oxidase subunit 1 (COI), 16S RNA] of ten species of Selenkothuria and related subgenera showed the polyphyly of this subgenus; monophyly was rejected by a likelihood ratio test. A geographical split divides the species of this subgenus into three different groups: one Indo‐West‐Pacific (IWP) group and two American groups. The IWP group is more closely related to Holothuria (Semperothuria) cinerascens and to other subgenera such as Roweothuria, Holothuria, and Vaneyothuria, whereas the two American groups are more closely related to each other and to some species of the subgenus Halodeima. These results suggest multiple parallel originations and diversification of ossicle morphology within the subgenus Selenkothuria. The current scheme of subgenera for the genus Holothuria is not supported, suggesting the need for a new classification. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 165 , 109–120.