Volume 32

Examination of unsorted microgastropod samples collected during the joint Russia-German research “Sea of Japan Biodiversity Studies (SoJaBio) Expedition” in 2010 and preserved in the National Scientific Center of Marine Biology, Far Eastern Branch of the Russian Academy of Sciences, Vladivostok, resulted in the finding of six species of the family Rissoidae. Among them, “Alvania” nihonkaiensis Hasegawa, 2014 is newly recorded both in Russian waters and on the northern slope of the Sea of Japan, and Punctulum reticulatum Golikov, 1986 was rediscovered for the first time since its original description. Geographical and vertical distributions of each species and their significance are updated and discussed.

New data on the records of synanthropic slug species of Limacus maculatus and Arion vulgaris in Belarus are analyzed. It is assumed that the penetration of these species into the territory of Belarus occurred from other parts of their modern range together with the imported goods.

The study of the anatomy of Euomphalia aristata from the Western Transcaucasia showed that these populations differ from other species of the genus and from the typical populations of E. aristata from the North Caucasus in anatomy of the genitalia. E. aristata in Transcaucasia is characterized by the separation of the distal parts of the male and female sections of the reproductive system, a long oviduct, a very short proximal part of the vagina, and the location of the vaginal appendages close to the mucous glands. In E. aristata from the North Caucasus (North Ossetia), the male and female parts of the genitals are not separated in the distal part, the oviduct is short, the proximal part of the vagina has an S-shaped bend, and the vaginal appendages are located at a noticeable distance from the mucous glands. On these grounds we distinguish E. aristata in Transcaucasia as a separate species.

E. aristata was described from the vicinities of Kislovodsk that is on the northern macro-slope of the Main Caucasian Ridge; therefore, the name E. aristata is applicable to the snails inhabiting this region. For molluscs living on the southern slopes of the Caucasus Range and further south, we propose the name Euomphalia schileykoi sp. nov.

This paper describes finding of 3 specimens of Skenea profunda (Friele, 1879) in the Arctic Basin from a depth of 3700-3800 The species had been previously reliably known only from the bathyal part of the North Atlantic and is confined to communities of sunken wood. This is the second finding of a taxon obligate for such habitats in the Arctic Ocean and confirms the assumption that there is a fauna associated with wood falls on the path of the Transpolar Drift Flow in the Central Arctic.

It is proposed to exclude Stenoplax lindholmii from the list of Japanese chiton species, which turned out to be a junior synonym of S. magdalenensis. Lectotype of Chiton lindholmii is designated.

One more tiny chiton of the genus Leptochiton is described from the shallow water of the Persian Gulf. The new species Leptochiton persianus sp. n. differs from other species of the genus living on coral reefs in shape of the tail valve with subcentral mucro, long central and first lateral teeth of radula, and round median denticle of the head of the major lateral tooth.

The terrestrial snails Brephulopsis cylindrica and Xeropicta derbentina are native to steppes of the Northern Black Sea region and; X. derbentina has also initially inhabited Eastern Mediterranean, the Caucasus, and Anatolia. However, in last decades the species are increasingly reported outside of their natural range which renders them as likely invasive. The paper aims to assess the ecological suitability of adjacent habitats in terms of the molluscs invasion. We address this using species distribution modelling (SDM). The selected environment predictors for SDM included 22 environment factors such as land cover, enhanced vegetation index (EVI), altitude, and 19 bioclimatic parameters. This suggests that the area with maximum suitability extends from the natural range to the Central Danube lowland in the West and up to the Volga Upland in the Northeast. These regions have similar EVI and are largely croplands. Among the predictors, the minimum temperature of the coldest month has the greatest impact on the modelling results, which agrees with the variable being the limiting factor for the distribution of subtropical invertebrates. The study reinforces the notions that X. derbentina and B. cylindrica are likely to further expand the boundaries of their range thus posing threats to native ecosystems.

The predatory gastropod mollusk Rapana venosa is included in the list of the 100 most dangerous invasive species of the Black and Mediterranean Seas, which determines the relevance of studying the species’ local populations in the areas of introduction. The first studied Rapa whelk population in Donuzlav Bay (NW Crimea) was one of the last to form and differs from populations in other areas of the Black Sea. Based on the results of studies in 2020, the characteristics of the population structure of R. venosa inhabiting the Donuzlav Bay and the adjacent marine area are shown. The data obtained are compared with the population characteristics of the Rapa whelk from other areas of the Black Sea. It is shown that at the stage of stabilization of the metapopulation, the phenotype of the adapted “norm” R. venosa of the Black Sea was formed.

The state of three populations of the adventitious species H. pomatia was studied on the basis of conchiometric, phenetic and genetic methods. According to the obtained data, the two newly described populations from the Belgorod and Lugansk regions differ both in metric and morphological indicators, as well as in the frequencies of alleles of isoenzyme loci. The reason for such disparity may be genetic-automatic processes, natural selection in newly developed territories, as well as chaotic invasion from various localities, either from native range, or from nearby biotopes.