Resurrection of the parasitic copepod genus Achtheinus Wilson, 1908 (Siphonostomatoida, Pandaridae), with redescription of A. oblongus Wilson, 1908, A. dentatus Wilson, 1911, and A. pinguis Wilson, 1912 based on museum collections.

[A genus of parasitic copepods, Achtheinus Wilson, 1908 (Siphonostomatoida, Pandaridae), is resurrected. Although it has been relegated in recent decades to a synonym of Perissopus Steenstrup & Lutken, Achtheinus is distinct from the latter in the dorsal plate system of free pedigers 2-4 and in the shape of the genital complex. The nominal species assigned to this genus are revised and A. oblongus Wilson, 1908, A. dentatus Wilson, 1911, and A. pinguis Wilson, 1912 are redescribed as valid based on museum collections including types deposited in the National Museum of Natural History, Smithsonian Institution, and the Swedish Museum of Natural History, Stockholm, and on newly collected specimens from Japanese sharks. These three congeners are distinct from each other in the relative lengths of the caudal rami and abdomen. Achtheinus japonicus Wilson, 1922, A. parvidens Wilson, 1923, Pholidopus ( A. ) intermedius Kurtz, 1924, A. galeorhini Yamaguti, 1936, A. platensis Thomsen, 1949, and A. impenderus Shen & Wang, 1958 are all synonyms of A. pinguis . Both sexes of A. oblongus and some copepodid stages of the genus are described for the first time. Le genre de copepode parasite, Achtheinus Wilson, 1908 (Siphonostomatoida, Pandaridae), est retabli. Bien qu'il ait ete considere au cours des recentes decennies comme synonyme de Perissopus Steenstrup & Lutken, Achtheinus en est distinct par le systeme de plaque dorsale des somites libres portant les deuxiemes a quatriemes pattes et par la forme du complexe genital. Les especes attribuees a ce genre ont ete revisees et A. oblongus Wilson, 1908, A. dentatus Wilson, 1911, ainsi que A. pinguis Wilson, 1912 sont redecrites comme valides a partir de specimens de collections incluant des types et deposes au National Museum of Natural History, Smithsonian Institution, et au Swedish Museum of Natural History, Stockholm, ainsi que de specimens nouvellement collectes sur des requins japonais. Ces trois congeneres sont distincts les uns des autres par les longueurs relatives des rames furcales et de l'abdomen. Achtheinus japonicus Wilson, 1922, A. parvidens Wilson, 1923, Pholidopus ( A .) intermedius Kurtz, 1924, A. galeorhini Yamaguti, 1936, A. platensis Thomsen, 1949, et A. impenderus Shen & Wang, 1958 sont tous synonymes de A. pinguis . Les deux sexes de A. oblongus et certains stades copepoditiques du genre sont decrits pour la premiere fois. , A genus of parasitic copepods, Achtheinus Wilson, 1908 (Siphonostomatoida, Pandaridae), is resurrected. Although it has been relegated in recent decades to a synonym of Perissopus Steenstrup & Lutken, Achtheinus is distinct from the latter in the dorsal plate system of free pedigers 2-4 and in the shape of the genital complex. The nominal species assigned to this genus are revised and A. oblongus Wilson, 1908, A. dentatus Wilson, 1911, and A. pinguis Wilson, 1912 are redescribed as valid based on museum collections including types deposited in the National Museum of Natural History, Smithsonian Institution, and the Swedish Museum of Natural History, Stockholm, and on newly collected specimens from Japanese sharks. These three congeners are distinct from each other in the relative lengths of the caudal rami and abdomen. Achtheinus japonicus Wilson, 1922, A. parvidens Wilson, 1923, Pholidopus ( A. ) intermedius Kurtz, 1924, A. galeorhini Yamaguti, 1936, A. platensis Thomsen, 1949, and A. impenderus Shen & Wang, 1958 are all synonyms of A. pinguis . Both sexes of A. oblongus and some copepodid stages of the genus are described for the first time. Le genre de copepode parasite, Achtheinus Wilson, 1908 (Siphonostomatoida, Pandaridae), est retabli. Bien qu'il ait ete considere au cours des recentes decennies comme synonyme de Perissopus Steenstrup & Lutken, Achtheinus en est distinct par le systeme de plaque dorsale des somites libres portant les deuxiemes a quatriemes pattes et par la forme du complexe genital. Les especes attribuees a ce genre ont ete revisees et A. oblongus Wilson, 1908, A. dentatus Wilson, 1911, ainsi que A. pinguis Wilson, 1912 sont redecrites comme valides a partir de specimens de collections incluant des types et deposes au National Museum of Natural History, Smithsonian Institution, et au Swedish Museum of Natural History, Stockholm, ainsi que de specimens nouvellement collectes sur des requins japonais. Ces trois congeneres sont distincts les uns des autres par les longueurs relatives des rames furcales et de l'abdomen. Achtheinus japonicus Wilson, 1922, A. parvidens Wilson, 1923, Pholidopus ( A .) intermedius Kurtz, 1924, A. galeorhini Yamaguti, 1936, A. platensis Thomsen, 1949, et A. impenderus Shen & Wang, 1958 sont tous synonymes de A. pinguis . Les deux sexes de A. oblongus et certains stades copepoditiques du genre sont decrits pour la premiere fois. ]