A review of three Asian species of the scale worm Hesperonoe (Annelida: Polynoidae), with descriptions of two new species and a new record of Hesperonoe hwanghaiensis from Korea

초록

To date, five species of the genus Hesperonoe, which are commensal to decapod crustaceans of echiuroids, have been described from Northern Hemisphere (Hartman, 1961; Uschakov and Wu, 1965; Averincev, 1990). In eastern Asia, only single species, H. hwanghaiensis Uschakov and Wu, 1959 has been recorded from Qingtao in China (type locality) and from several sites in Japan, where commensalism of this species to Upogebia major (Crustacea: Decapoda) was shown (Sato et al., 2001). Recently, many specimens of scale worms belonging to the genus Hesperonoe have been collected from tidal flats in the Korean western coast of Yellow Sea during our survey on the population ecology of the mud shrimp U. major (see, Hong et al., 2012). In the present study, we taxonomically examined the Korean Hesperonoe specimens, and revealed that two species are included; one undescribed species and another one with its morphology well agreeing with the original description of H. hwanghaiensis by Uschakov and Wu (1959). We also reexamined the Japanese Hesperonoe specimens, which were previously identified as H. hwanghaiensis by Sato et al. (2001), because Sato et al. (2001) noted several morphological differences between Japanese and Chinese populations, regarding these differences as intra-specific variation. However, we found clear difference between them based on the morphological comparison between Korean and Japanese specimens of “H. hwanghaiensis”, concluding that the Japanese specimens do not belong to H. hwanghaiensis, but to an undescribed species. Here, we review the taxonomic characteristics of the three Asian Hesperonoe species, i.e., H. hwanghaiensis newly recorded from Korea and two additional Korean and Japanese species which were described as new species.