Three species of hydrothermal-vent-associated pycnogonids were collected from a feature described as a clump of vent substrate with tubeworms found along the Endeavour Segment of the Juan de Fuca Ridge in the Northeast Pacific. Two of the species are known, having been described from vents in the same vicinity, while the third is a new species, Sericosura dissita. The new species is described, illustrated, and compared with another vent-associated Sericosura species, while the two known species in this collection are diagnosed and their distributions are given.
A new terrestrial tubificid oligochaete, Bothrioneurum grandisetosum sp. n., is described. It is unique in the possession of giant ventral setae in segments V-VI, sudden stomachal dilatation, thickened septa in posterior segments, and the absence of paratrial glands.
The zoeal development of the porcellanid crab Novorostrum indicum is described and illustrated from laboratory-reared material. Zoeal characters of this species appear to support the establishment of Novorostrum. Furthermore, a closer affinity of this genus with Petrolisthes ornatus, P. japonicus, and P. elongatus than with other species of Petrolisthes for which the larval morphology is known, and also the exclusion of P. ornatus from Novorostrum, are supported.
The generic assingment of Acanthomysis quadrispinosa Nouvel, 1965, which was later placed in Acanthomysis s. s. by Holmquist, is confirmed. A new genus, Notacanthomysis, is established for two known species, Acanthomysis hodgarti (W. M. Tattersall, 1922) and A. laticauda Liu and Wang, 1980, which are redescribed. The new genus is characterized by the form and armature of the fourth pleopod of the male and the telson.
Seventeen taxa of aquatic Oligochaeta belonging to four families were recorded from the Ozegahara Mire, central Honshu, Japan, on the basis of specimens collected from 1994 to 1996. Pristinella rosea (Piguet, 1906) is illustrated and recognized as distinct from P. jenkinae (Stephenson, 1931). The oligochaete fauna in bog pools was poorer than that in streams in the Mire, mainly composed of naidids and enchytraeids. On the other hand, a tubificid, Bothrioneurum vejdovskyanum Stole, 1886, which is fully described and illustrated herein, was exclusively common in the bog pools, being abundant at their shallow margins and in temporary waters in the Mire. This species is suggested to be amphibious and to reproduce mainly asexually. The impoverished oligochaete fauna in the bog pools may be due to such factors as instability of water level, low pH, deficiency of available food, and oxygen depletion of the water during the long winters.
Two new enchytraeids from Changbaishan Mountain in north-eastern China are described. Both species lack lateral setae. Fridericia unisetosa sp. nov. is diagnosed by the absence of spermathecal diverticula and clitellar gland cells dorsally, while Fridericia paraunisetosa sp. nov. is characterized by having 6-8 sessile spermathecal diverticula and dorsal pores from XIII. The only other Fridericia species known to lack lateral setae entirely, the North American F. silvestris (Leidy, 1882), differs in having a longer body and more setae in each ventral bundle.
Two new species, Agathidium (Neoceble) naturale sp. nov. and A. (N.) multitodum sp. nov., and a new subspecies, A. (N.) omogoense yamaokai subsp. nov., are described with illustrations of important features. Anisotoma japonica Portevin, 1908 is synonymized with A. (N.) dubium Portevin, 1908. A key to 10 species of the subgenus Neoceble in Kyushu is given.