Austinogebia narutensis, burrow, commensalism, eastern Japan, Hesperonoe hwanghaiensis, mud shrimp, scale worm, Upogebia major
The scale worm Hesperonoe hwanghaiensis Uschakov and Wu, 1959 (Annelida: Polynoidae) is recorded from eastern Japan, based on four specimens collected from Akkeshi Bay, Hokkaido, and Kashima-nada, Ibaraki Prefecture. In Akkeshi Bay, three specimens (body length of a complete specimen: 40 mm, body width without parapodia: 4.0–4.5 mm), which are the largest of all Japanese specimens including previous records, were found from mud and sand sediments at intertidal flats, where a mud shrimp Upogebia major (De Haan, 1841) was collected simultaneously. In Kashima-nada, a complete mature male specimen (body length: 23 mm, body width without parapodia: 2.7 mm) was collected by dredging at subtidal sandy bottom at a water depth of 7.6 m, where another mud shrimp Austinogebia narutensis (Sakai, 1986) was collected simultaneously. The morphological characteristics of these specimens basically agreed with those of the previous records on the specimens collected from western Japan, with a diagnostic characteristic of the presence of a row of the more conical macrotubercles (up to 28 in an elytron of the complete specimen from Akkeshi Bay, and up to 3 in that from Kashima-nada) on the posterior surface of the elytra in the larger specimen. The present result suggests that the scale worm is commensal with not only U. major but also A. narutensis in its habitats extending from intertidal flats in semi-enclosed inner bays to subtidal bottom in open coasts.
編集・発行 : 日本動物分類学会 制作・登載者 : 株式会社国際文献社