Volume 20

During the study of the conchological variability of the land molluscs of the genus Chondrula in the south-east part of Ukraine and Crimea was discovered the form with specific structure of the aperture teeth which does not correspond to description of the known conchological forms of the widespread species Ch. tridens. The shells of Ch. tridens martynovi subsp. nov. with well developed aperture teeth are characterized by the following characters: 1) the angular tooth is not limited to the knoll or short comb on the aperture edge but sharply bends down and forms a low fold parallel to the parietal lamella; 2) palatal and suprapalatal teeth fuse to form the single well visible crestform lamella. Shells with incompletely formed teeth can resemble Ch. tridens tridens. The preliminary map of the distribution of Ch. tridens martynovi and Ch. tridens tridens on the territory of Ukraine was compiled on the basis of the materials of the State Museum of Natural History (Lviv). Brephulopsis konovalovae sp. nov. differs from B. bidens in shorter shells, more convex whorls and ribbed surface. The populations of B. konovalovae and B. bidens live sympatrically in the locus typicus in the mountain Crimea and do not form transitional forms.

During the investigation of the land mollusc fauna of the Donetsk upland (Eastern Ukraine) and adjoining territories three new species of the genus Helicopsis were discovered. One of them, H. subfilimargo sp. nov., is similar conchologically to Crimean H. filimargo, but clearly differs from it in a number of anatomical characters. The photographs illustrate the intrapopulation variability of the conchological and some anatomical features of H. subfilimargo sp. nov., H. martynovi sp. nov., H. luganica sp. nov. The conchological variability and some peculiarities of the internal structure of H. dejecta from Donetsk upland and adjoining territories are also demonstrated.

Population genetic structure of the land snails of the genus Brephulopsis (B. cylindrica and B. bidens) and their hybrids has been studied using of three polymorphic loci of esterases of foot tissues. Genetic patterns of allozyme variability of hybrid forms were similar to those for B. bidens. A similar result is obtained when using multilocus genotypes allozymes. On the other hand, the hybrid forms are characterized by an intermediate (“chimerical”) shell morphology between the two parental species. The values of effective population size were estimated by the Slatkin method of “private” alleles and the Kohn’s rarefaction curve method. These values were in the range from 20 to 60 individuals. 

Morphology of the soft body, copulative apparatus and taxonomically significant part of intestine of slugs from southern Magadan Region was examined. Basing on published and original data four species were recorded — Deroceras (Deroceras) laeve (Müller, 1774), D. (Agriolimax) altaicum (Simroth, 1886), D. (A.) agreste (Linnaeus, 1758) and D. (A.) reticulatum (Müller, 1774) introduced on Tauy Bay shore. Morphological characters of Far Eastern and Baikalian specimens of D. altaicum are discussed.

For the first time for Japan freshwater limpets Acroloxus orientalis Kruglov et Starobogatov, 1991 were recorded in the stream of central Hokkaido (Tomakomai city vicinities). Both the genus Acroloxus and family Acroloxidae are for the first time found in Japan. External morphology of shell and soft body as well as copulative apparatus are described.

The history of study of Siberian freshwater malacofauna between the end of XVIII and the middle of XX centuries (year 1952) is outlined. Data about professional malacologists, who studied Siberian molluscs, are given as well as information about most important collections of Siberian freshwater malacofauna of this period. The history of formation of continental molluscs collection of the Zoological Institute RAS (formerly Imperial Zoological Museum in SanktPetersburg) is traced. The history of study of Siberian freshwater molluscs is divided into three stages: “primordial” (second half of XVIII — middle of XIX centuries), “expeditionary” (middle of XIX — middle of XX centuries), and “regional” (middle of XX century — present).

A brief review of distirbuiton of populations of Rapana venosa in the World Ocean is presented. Short information concerning the formation of metapopulation of R. venosa in the Black Sea and taxonomical history of the species are given. The ecomorphs found off Crimean shores were examined with the emphasis to ecological conditions. It has been demonstrated that presently Rapana metapopulation in the Black Sea consists of numerous populations which differ primarily in conchological characters and size structure. Trophic specialization entails appearance of dwarf forms and influences formation of shell coloration. Studies of protoconchs allowed to conclude that colour pattern is determined on the earliest stages of shell development and later is influenced by environmental factors during the shell growth. The shell characters were compared in several Rapana populations and intrapopulation variability, age and sexual differences were demonstrated. Starting in 2007 the relative shell growth has been increasing despite the normal tendency of slowing of the growth rate with age. This phenomenon is connected with improvement of ecological situation in general, and, the most important, with increasing of forage reserve of Rapana. The pathways of infraspecies forms formation are presented in relation to possible scenarios of environmental changes.

The shell and radula comparative and illustrated description of all three genera of the family Valvatidae (Valvata s.str., Cincinna and Borysthenia), inhabiting the European fresh-waters are provided. Special emphasis paid to the embryonic shell and radula morphology of Cincinna piscinalis (Müller, 1774) — one of the most common valvatid species in Ukraine. Details of the protoconch of Borysthenia menkeana (Jelski, 1863) is studied with aid of the scanning electron microscopy for the first time. Embryonic shell of those species belonging to all genera discussed possesses identical type of ornamentation («woolen stocking »); it is revealed that valvatid species can be distinguished by proportions of their protoconch and partly by its size. Differences in dimensional characteristics of a protoconch confirm and complete the concept of generic independence of the discussed valvatid groups. Radula of valvatid is highly variable intraspecifically; its aptitude for the species differentiation is limited and requires of additional detailed study of significant set of new data. 

The new localities of Boreoelona sibirica, at East Siberian snail species (Mollusca: Gastropoda: Bithyniidae), are presented. Descriptions of the shell and copulative apparatus of representatives of the species from waterbodies of Western Siberia and Middle Urals are provided.

Illustrated descriptions of Columella talgarica sp. nov., Leucozonella corona sp. nov., and Angiomphalia nucula sp. nov. from Kazakhstan and Kirgisia are given. Holotypes of the species are deposited in Zoological Museum of Moscow State University (ЗММУ, ZMMU).