Fusinus juliabrownae n. sp. is described from the southern and eastern coasts of Korea. Though cited and figured widely in the Korean literature, it has not hitherto been recognized as a separate species. It is compared with F. ferrugineus (Kuroda & Habe, 1960), F. perplexus (A. Adams, 1864), F. nigrirostratus (E. A. Smith, 1879) and F. tuberosus (Reeve, 1847). The new species represents a northward range extension for the genus on the continental coast of the Japan Sea.
A new gastropterid species, Enotepteron hayashii, collected from the Sea of Japan, is described herein. Enotepteron is a small genus characterized externally by a small globular protuberance (sphere) on the posterior edge of both parapodia. E. hayashii differs from the previously known species by the presence of a small knob-like spur on the median line of the posterodorsal end of the mantle shield. This paper represents the first record of this genus from Japan.
The HOV Shinkai 6500 discovered four species of the bivalve family Vesicomyidae, namely Calyptogena (Ectenagena) phaseoliformis,C. (E.) extenta,C. (E.) sp. and C. (Archivesica) laubieri kurilensis n. subsp. in the southern extremity of the Chishima (Kurile) Trench. The morphological identifications of all species were corroborated by molecular analyses of symbiotic bacterial 16S rRNA genes and mitochondrial cytochrome c oxidase subunit I (COI) genes.
Solemya pervernicosa, which had previously been regarded as a bathyal species restricted to northeastern Japan, occurred in the sediment underneath whale carcasses submerged experimentally on the shelf off Cape Noma-misaki, Satsuma Peninsula, southwestern Japan, at depths of 219–254 m. This occurrence represents a significant range extension. Transmission electron microscopic observations of the gill tissue revealed dense bacteria in the epithelial cells. A molecular phylogenetic analysis strongly indicated that these bacteria are thioautotrophs closely related to the thioautotrophic symbionts associated with Solemya reidi and Acharax johnsoni. Analysis of carbon and sulfur isotopes of soft tissues of S. pervernicosa proved that this bivalve depends nutritionally on thioautotrophic symbionts. However, it is not clear at present whether the symbiont is transmitted vertically, as with some other chemosynthetic bivalves, or environmentally.
In this study we measured the life orientations of nine infaunal bivalve species quantitatively and examined tendencies and differences between species. The results indicated that the distributions of life orientation in individuals of local populations are statistically close to the Normal distribution in many species. In three species, Ruditapes philippinarum, Cyclina sinensis and Laternula marilina, the smaller the individuals are, the more of them lean their commissure plane greatly, increasing the diversity of their life position. Moreover, three closely related species, Meretrix lusoria, M. petechialis and M. lamarckii, whose shapes are hardly different, show significant differences in anteroposterior life orientation. This may indicate different behavioral characteristics under different habitat energy levels and thus reveal the meaning of life orientations.
The feeding behavior and palatability to Acusta despecta despecta of the pollens from four plant species [Alpinia zerumbet (Shell ginger), Bidens pilosa var. radiata (Beggars tick), Hibiscus rosa-sinensis (Hibiscus) and Lilium sp. (Lily cultivar)] were investigated. Ac. d. despecta fed on the pollen of all the plant species, but showed a preference for that of Al. zerumbet, judging from the high feeding rate. Pictures of scats taken by scanning electron microscope revealed that the pollen of Al. zerumbet in the scat was broken into fragments, while those of other three species were kept their original shape. The difference in digestibility between the pollen of Al. zerumbet and other three plants could be one of the determinant factors of the pollen-feeding preference of Ac. d. despecta.
Olivella fulgurata (A. Adams & Reeve, 1850) (Gastropoda: Olividae) is a common inhabitant of exposed sandy beaches in the southern part of the Boso Peninsula, Japan. The population biology of this species on the eastern coast of Sagami Bay, Miura Peninsula, Central Japan, was studied from January 2008 to June 2009. Newly recruited juveniles of O. fulgurata appeared from May to June, and grew rapidly thereafter. The lifespan of O. fulgurata was estimated to be about 1 year.