Volume 35

An impressive, medium-sized new camaenid species, Ganesella tamchuc sp. nov., is described from Hà Nam Province, northern Vietnam. Ganesella tamchuc sp. nov. is similar to Ganesella emma (Pfeiffer, 1863) in its general shell coloration pattern but differs by having a smaller shell size; three distinct color belts on the shell surface, including a white belt at the keel and two dark brown belts situated above and below the keel; strong radial ribs that protrude from the shell surface and also present at the umbilicus and within the aperture; a distinctly keeled last whorl that becomes weak behind the peristome; and a widely open umbilicus through which all whorls are visible.

A new deep-water species Stenosemus formosaensis sp. nov. collected in the northeast of the South China Sea southwest of Taiwan is described. From other species of the genus Stenosemus the new species is distinguished by dark olive stripes radially arranged on head valve and lateral areas and longitudinally on pleural areas, and also by the arrangement of grooves of different tegmentum zones.

This paper provides first reliable data on the finding of the bivalve mollusc Thracia septentrionalis in the Sea of Japan. A live specimen (L = 24.4 mm) was collected in June 2003 in Peter the Great Bay at a depth of 70 m on medium-grained sand. The data on geographical distribution and ecology of the species in the northern Pacific Ocean are summarized. The validity of Thracia seminuda Scarlato, 1981, previously synonymized with T. septentrionalis, is confirmed. Diagnostic differences between these species are specified and illustrated.

In the Kherota River (Russian Black Sea coast), freshwater mussels not previously known in the area were discovered and morphologically identified as Unio gontierii Bourguignat, 1856 (Bivalvia: Unionidae). The mussel species identity was verified by analysis of the mitochondrial gene sequence encoding cytochrome c oxidase subunit I (COI). The diversity of the eight studied microsatellite loci in the studied sample was rather high (the average number of alleles per locus was 4.75, the observed heterozygosity was 0.50±0.08). The aforementioned facts, in conjunction with the substantial distribution of the bitterling Rhodeus colchicus Bogutskaya et Komlev, 2001 along the Russian Black Sea coast, whose larvae develop in the bivalves, indicate that Unio gontierii is an indigenous inhabitant of the Russian part of the Caucasian coast and not a recently human-introduced species.