The genus Trachypenaeopsis Burkenroad, 1934 has been known in the Indo-West Pacific region by two species, T. richtersii (Miers, 1884), described from Mauritius and recorded afterwards as far as Indonesia, Japan, and Hawaii, and T. minicoyensis Thomas, 1972, known only from the Laccadive Is. The present work shows that T. minicoyensis is a synonym of T. richtersii, that identifications of material from China, Taiwan, and Hawaii are erroneous and that these specimens are not morphologically distinguishable from the Atlantic species, T. mobilispinis (Rathbun, 1915), described from the West Indies. DNA analyses show that Pacific specimens other than T. richtersii belong to one species: genetic divergence is not higher than 2.2%, while the genetic distance between Pacific and Atlantic populations averages 3.6%. The absence of morphological differences between these two sets of populations indicates that the populations are becoming genetically different but cannot yet be considered separate species. The colour patterns of the Atlantic and Pacific specimens have not been determined so it is possible that these populations could eventually be shown to represent separate sibling species.
Crustacea, Decapoda, Penaeidae, Trachypenaeopsis, review, morphology, molecular analyses, distribution.