Two new species, Pararetifusus kantori sp. nov. and P. kosugei sp. nov. (Buccinidae: Colinae) are described from the Bering, Okhotsk and Japan seas. New data were obtained on the morphology of the type species of the genus Pararetifusus, P. tenuis.

Based on the shell structure, anatomical and radular characters of seven species recorded from the Russian marine fauna and attributed to genera Latisipho and Helicofusus, L. pharcidus is reduced to the junior synonym of L. hypolispus, whereas L. errones, L. jordani, L. georgianus, and H. luridus – to the synonyms of L. hallii.

Some shells of Chlamys behringiana bearing mollusks Trichamathina nobilis at upper valves were collected near North Kurile Islands. Egg capsules were found under most of shells of T. nobilis. Descriptions of egg capsules and larval shells are presented. Evidences of kleptoparasitic relationships between T. nobilis and C. behringiana are presented.

Radular morphology was studied in detail in 64 species of 7 genera of Turrinae. It is suggested that the so-called “central tooth” is formed by a fusion of 3 teeth: the central one and a pair of lateral. A similar condition was found in some representatives of the subfamilies Cochlespirinae and Crassispirinae (Turridae).

Anomalies in female reproductive system (imposex) were recorded in populations of Buccinum undatum and Nucella lapillus in the White and Barents seas. For Buccinum cyaneum from the Barents Sea the anomalies in reproductive system were not found. 7.7% of females of Buccinum undatum from the White Sea had imposex in 1976, and 6.5% in 2005; in the Barents Sea in 2005 – 29.5%. 46.1% of females of Nucella lapillus from the Barents Sea have imposex. The degree of development of imposex demonstrated that the strait Velikaya Salma of the White Sea is less polluted than the Dal’nezelenetskaya Bay of the Barents Sea. By imposex development and probably by organotin pollution the Barents Sea corresponds to the most clean in this respect areas of the British Islands coast – north-eastern England. Comparison of the data of 1976 and 2005 from the White Sea suggested that certain low percentage of females of Buccinum undatum with imposex may be present in populations inhabiting non-polluted areas.

The composition of opisthobranch mollusk fauna of the Murman coast of the Barents Sea is described using own and literature data reviewed for the first time. Data on distribution and ecology are given, some taxonomical problems are discussed. Three species new for Russian fauna — Polycera quadrilineata, Doto fragilis and Eubranchus tricolor and one species new for the Subarctic — Embletonia pulchra were discovered. The influence of periodical temperature changes on the opisthobranch fauna composition is discussed.

The Antarctic genus Guyvalvoria Vayssière, 1906 is revised. The type species of the genus, G. francaisi Vayssière, 1906 is redescribed based on the study of the type and new material. Two new species of the genus Guyvalvoria, G. gruzovi sp. nov. and G. savinkini sp. nov. are described from the Davis Sea and Subantarctic Kerguelen Island. In addition, a new genus and species, Murmania antiqua gen. et sp.nov. is described from off the Murman coast of the Barents Sea (depth 60-300 m). The latter taxon is characterized by a wide body, numerous branched rows of the digestive gland and moderately developed notal rim with an elevated ridge. Radular teeth of Murmania antiqua possess unusual clusters of lateral denticles. The Antarctic genus Guyvalvoria and Subarctic genus Murmania gen. nov. have some similarities in the external appearance, presence of numerous branches of the digestive gland and a tendency to shift of the anus caudally. Morphological peculiarities of the new taxon suggest a new interpretation of the head composition in the family Tergipedidae: the tergipedid head is formed with involving of the postoral lobes of the anterior foot, as distinct from the “typical head”, characteristic of most aeolidacean nudibranchs. This conclusion is supported by a number of examples from the family Tergipedidae and other families of the aeolidaceans. Both Murmania gen. nov. and Guyvalvoria Vayssière, 1906 are considered as one of most basal within the Tergipedidae; transformations of the digestive gland within the family are discussed. Ревизован антарктический род Guyvalvoria Vayssière, 1906.

A new species Merdigera invisa Kijashko sp. nov. from the high-mountainous part of Northwest Caucasus is described. Taking into account the features of this species, diagnosis of subfamily Merdigerinae Schileyko, 1984 is defined more exactly.

Based on conchological and anatomical study, a new species and genus of the family Enidae is described from Western Transcaucasia.

Size distribution, age, and sex ratio were studied for a population of baikalian endemic gastropod Maackia herderiana living on shallow-water rocky platform in South Baikal Lake. Six size groups were recognized. The age was determined from the number of annual growth rings on the shell. Each of groups I-V contained snails of two ages corresponding most probably to different generations: spring and autumn. Snails of 4 to 8 years old were assigned to the group VI. The sex ratio in M. herderiana was generally close to 1:1. A tendency to deficiency of females in older snails was similar to that described earlier by Kozminsky [2003] for Bithynia tentaculata. It could be explained by a longer life span of males and higher reproductive expenses of females.

Based on 63 nucleotide sequences 588 base pairs long of the fragment of mitochondrial gene coding for the 1st subunit of cytochrome с oxydase (CO1) of Baikalian endemic mollusc Baicalia carinata (Dybowski, 1875), we show that this species splits into three clades, which correspond to three populations: south (Bolshie Koty, Murinskaya Banka), north-west (from Maloe More to Id. Yarki) and north-east (from Gremyachinsk to Point Pongonie). Each clade includes sequences belonging to three different species of genus Baicalia. This fact indicate a lower degree of genetic differences (about 5%) between morphological species in comparison with differences between populations of the same species (up to 6.8%). We argue that the species of Baicalia Martens, 1876 occurred allopatrically in spite of their parapatric current distribution. Migration and possible inter-specific hybridization played important role in shaping of their current genetic polymorphism.

The shell pores of Baikalian euglesid bivalves from the littoral of South Baikal Lake were for the first time studied with the SEM. It was shown that the pores are unevenly distributed in the 8 species studied [Henslowiana semenkevitschi (Lindholm, 1909), H. trigonoides (W. Dybowski, 1902), Euglesa granum (Lindholm, 1909), E. minuta (Kozhov, 1936), E. korotnevi (Lindholm, 1909), E. platyvalva (Slugina et Starobogatov, 1994), Cingulipisidium koshovi (Starobogatov et Streletzkaja, 1967), Conventus raddei (W. Dybowski, 1902)]. In subumbonal part of E. granum and E. minuta shells, the pore density is 1.5 times higher; the pore width and height in E. minuta are about 2 times more above the mantle line than in marginal part of the shell. The pores in subumbonal part of E. platyvalva shell are, on the contrary, 1.5 rarer than above the mantle line and 2.6 times rarer than at the shell margin. Among the species studied, only E. platyvalva has pores between the mantle line and the lower valve margin, which has not been previously found in the family Euglesidae. In the subumbonal part of this species shell the largest pores were observed: 6.34 μm, whereas the smallest pores in this part of the shell were found in С. kozhovi (2.22 μm). The pores of three species, H. semenkevitschi, E. granum, C. koshovi, are surrounded by additional thickening on inner side of valves.

The recently published catalogue of the former USSR molluscs [Kantor, Sysoev, 2005] unfortunately provides incomplete data on modern distribution of many species of land molluscs on the territory of Ukraine. Some species are not mentioned for Ukraine (Deroceras caucasicum, Limax maximus, Malacolimax tenellus, Arion circumscriptus, Cepaea hortensis, C. nemoralis, Stenomphalia ravergiensis) or for countries of the former USSR (Acicula perpusilla, Chondrula microtraga, Thoanteus ferrarii, Helicodiscus singleyanus, Daudebardia rufa, D. brevipes, Aegopinella nitens, Ae. nitidula, Vitrea diaphana, Deroceras turcicum, Limax bielzi, Arion distinctus). Faunistic investigations of Ukrainian malacologists allow to supplement essentially the catalogue data.

New diagnosis of the genus Testudinalia (type species Patella tessulata Müller, 1776) is given. This genus is closest to the genus Lottia because both species Testudinalia tessulata and T. scutum have rudiments of the marginal teeth. The specific name Patella tesselata Müller, 1779 is an incorrect subsequent spelling. Original description of Patella testudinalia Müller, 1776 is exclusively brief and lacking the figures, and this name should be regarded as a nomen dubium. For the first time Testudinalia persona (= Notoacmea persona sensu Lindberg, 1981) was found in the Far Eastern seas of Russia.

A gastropod with unusual morphology was found in the Upper Jurassic of Central European Russia. It is assigned to a new family Berendinellidae fam. nov., as Berendinella rossica gen. et sp. nov. This family is preliminarily referred to the superfamily Cerithiopsoidea.