A new species in the genus Heteromysoides (Crustacea, Mysida, Mysidae) from Songkhla Lagoon, southern Thailand

Abstract

A new mysid, Heteromysoides songkhlaensis, is reported from shallow water in the Songkhla Lagoon, southern Thailand. The new species is closely similar to H. nana in having a triangular rostrum and the eyestalk without a process at the anteromesial corner. However, the new species can be readily distinguished from H. nana by three setae on the inner margin and five setae on distal margin of the second segment of the mandibular palp; the carpopropodus of the fifth and sixth thoracic endopod of the new species is composed of four articles, and the telson of the new species is distally rounded, shorter than the sixth abdominal somite, and 1.3 times longer than its basal width; the spines on the telson form elongated spines from the distal to posterior margin. The new species also resembles H. dennisi, H. simplex, and H. stenoura; however, it differs by (1) the presence of a rounded distal margin of telson, and (2) absence of a sharp process on the distolateral corner of the eyestalk.