Taxonomy of the heavily exploited Indo-Pacific sandfish complex (Echinodermata: Holothuriidae)

Two commercially valuable holothurians, the sandfish and golden sandfish, vary in colour and have a confused taxonomy, lending uncertainty to species identifications. A recent molecular study showed that the putative variety Holothuria (Metriatyla) scabra var. versicolor Conand, 1986 (‘golden sandfish’) is a distinct species from, but could hybridize with, H. (Metriatyla) scabra Jaeger, 1833 ('sandfish'). Examination of the skeletal elements and external morphology of these species corroborates these findings. The identity of H. (M.) scabra is unambiguously defined through the erection and description of a neotype, and several synonyms have been critically re-examined. The nomenclaturally rejected taxon H. (Metriatyla) timama Lesson, 1830 and H. (M.) scabra var. versicolor (a nomen nudum) are herein recognized as conspecific and are allocated to a new species, Holothuria lessoni sp. nov., for which type specimens are described. The holotype and only known specimen of H. aculeata Semper, 1867, has been found and is redescribed. It is considered to be a valid species. Taxonomic clarification of this heavily exploited species complex should aid its conservation and permit species-specific management of their fisheries.