Two new species of the genus Macrocheles, M. coenosus and M. subcoenosus, are described and illustrated on the basis of material collected in Hokkaido, northern Japan. These species are assignable to the carinatus species group of the genus, and this is the first record of the group from Japan.
A new species of the genus Isobactrus is described from Ponape Island under the name of Isobactrus ponapensis sp. nov. The new species closely resembles I. pacificus Bartsch, 1989 and I. luxtoni Bartsch, 1992. But, I. ponapensis is distinguished from these two species by the anal foramen placed partly on the striated membranous cuticle and the absence of outlying perigenital setae in the male. The genus Isobactrus is recorded from Micronesia for the first time. Character state distribution for 22 diagnostic characters in the genus is also given. Isobactrus species from the Mid-Pacific region are uniquely characterized by the absence of the lateral seta on the third coxal region and by having two setae on the first genu.
Panthalis mitsukurii (Annelida : Polychaeta : Acoetidae) was described by Izuka (1904), based on four specimens collected from Sagami Bay. The species was later transferred to the genus Eupolyodontes by Malaquin and Dehorne (1907). Types were not known to exist. Based on the rediscovery of two specimens (A and B of Izuka, 1904) and one proboscis in the University Museum and Misaki Marine Biological Station of The University of Tokyo, the description is supplemented. Fine structure of the setae are shown using the scanning electron microscope.
Four new subspecies of Carabus (Ohomopterus) albrechti are described : C. a. hidakanus nov. and C. a. itoi nov. from Hokkaido, and C. a. echigo nov. and C. a. awashimae nov. from the Japan Sea side of central Honshu and Awashima Is., respectively.
Lysmata zacae Armstrong, 1941, previously known only by the type specimens from Savai'i Island, Western Samoa, is redescribed on the basis of two nonovigerous females and one ovigerous female newly collected from southern Japan and New Caledonia. The rediscovery of this species suggests that it is widespread in the western Pacific.
Eight species of marine Tubificidae, including two new species and four first records from Japan, are reported from Hokkaido. Nootkadrilus crassisetosus sp. n. is distinguished from N. verutus Baker, 1982 in having penial setae of equal length. Limnodriloides ezoensis sp. n. differs from L. victoriensis Brinkhurst and Baker, 1979 by having an oesophagus without diverticulae. Three species, Rhizodrilus pacificus (Brinkhurst and Baker, l979), Aktedrilus knoellneri Erseus, 1987 and Tubificoides pseudogaster (Dahl, 1960), are redescribed.
A new species of the bethylid wasp genus Pseudisobrachium Kieffer, 1904, is described under the name of P. hongkongense based on a female from Hong Kong. This is a third Oriental species of this genus and is the first record of the genus from Hong Kong.
Discorsopagurus cavicola, the third species of the genus, is described and illustrated on the basis of specimens from Mutsu Bay and Hakodate Bay, northern Japan. It strongly resembles D. schmitti (Stevens) from the west coast of North America, but shows differences in structure of the fifth abdominal tergite, development of the uropodal exopod and relative length of the ocular peduncle. This new species inhabits boreholes made by the rock-boring clam, Barnea manilensis inornata (Bivalvia : Pholadidae) or an uncertain host.