<i>Longipedia tratensis</i> <b>sp. nov.</b> (Copepoda: Canuelloida: Longipediidae) from Trat Province, Eastern Gulf of Thailand

Many specimens of the canuelloid copepod genus Longipedia (Copepoda: Canuelloida) were collected during a meiofauna survey in May 2023 at the intertidal zone at Mairood Sandy Beach of Trat Province, Eastern Gulf of Thailand. These specimens turned out to be a new species, Longipedia tratensis sp. nov. of the family Longipediidae. At present, 16 species of the genus Longipedia are known. Longipedia tratensis sp. nov. is the seventeenth species of the genus. The new species, L. tratensis sp. nov., is morphologically similar to L. thailandensis in the presence of an anterior unguiform projection on P2 enp-1, in the lack of a posterior armature element on P2 enp-2, and in the presence of a spiniform inner element on P4 enp-1. Longpedia tratensis sp. nov. differs from L. thailandensis in the following characters: number of setae on proximal endite of maxilla (four in L. tratensis sp. nov., but six in L. thailandensis), P1 coxa with small outer spinules proximally (present in L. tratensis sp. nov., absent in L. thailandensis), P1 basis without long setules on outer margin (with several long setules proximally in L. tratensis sp. nov.), relative length of the inner seta on P2 and P3 enp-1 (comparatively longer in L. tratensis sp. nov.), and structure of the male P5 (both baseoendopods confluent in L. thailandensis, but separated in L. tratensis sp. nov.).