New habitats of Lymnaea (Stagnicola) saridalensis Mozley, 1934 were discovered in the former riverbed reservoirs of the basins of the Khopor and Sura rivers in the Volga Upland (Penza region). The parameters of the shell and the indices of the copulative apparatus (ICA), which is used for distinguishing species, were determined. Studied populations were characterized by a significant variability of ICA (0.183 ± 0.01 and 0.276 ± 0.012).

Gibbinae subfamily in the Mauritius Island is represented by four taxa of generic rank. The anatomy of the type species of three of them has been known previously. The description of the reproductive tract of the fourth – Plicadomus sulcatus (Müller, 1774) is presented. It is shown that under striking conchological differences the anatomy of members of all four taxa is very similar and differs in quantitative characters only (the ratio of the length of the separate elements: the vagina / free oviduct and the relative length of the penis.). On the basis of this fact it was concluded that Mauritian Gibbinae is represented by a single genus Gibbus Montfort, 1810 with four subgenera (Gonospira Swainson, 1840, Plicadomus Swainson 1840, Gonidomus Swainson, 1840, and Gibbus s. str.).

Large population of Caucasian mollusc Harmozica ravergiensis was found in the Gvozdiv village in Kyiv region. There were no reports of this species from Central Ukraine before now and this locality is most northwestern for it. Population was monitored during the 2015-2017 and evidently survived two winters on the open grounds in this period. Shell and reproductive anatomy of H. ravergiensis from Gvozdiv are described and illustrated. The presence of the species in area is discussed. Moreover, another new finding of H. ravergiensis is reported: in Petrykivka village (Dnipropetrovsk region, Southern Ukraine) in 2016.

In the course of preparation of a new molecular phylogeny of Conoidea based on exon-capture some new species and species with notable morphology were revealed. The taxonomy of these species is discussed and the radula of most of them illustrated for the first time. New genera are described: Comispira gen. nov. (Cochlespiridae), type species Leucosyrinx mai Li et Li, 2008; Pagodaturris gen. nov. (Clavatulidae), type species Pleurotoma molengraaffi Tesch, 1915. New species: Comispira compta gen. et sp. nov., Sibogasyrinx sangeri sp. nov. (both Cochlespiridae), Pagodaturris philippinensis gen. et sp. nov. (Clavatulidae), Horaiclavus micans sp. nov., Iwaoa invenusta sp. nov. (both Horaiclavidae), Lucerapex cracens sp. nov., Lucerapex laevicarinatus sp. nov. (Turridae), Heteroturris kanacospira sp. nov. (Borsoniidae). Epideira Hedley, 1918 reallocated from Pseudomelatomidae to Horaiclavidae The radulae of Kuroshioturris nipponica (Shuto, 1961) (Turridae), Leucosyrinx verrillii (Dall, 1881), Leucosyrinx luzonica (Powell, 1969), comb. nov. are illustrated for the first time.

Eleven egg cases of Beringius marshalli (Dall, 1919) (Gastropoda: Buccinidae: Beringiinae) were found in the north part of Okhotsk Sea. Egg cases consist of 2-7 rounded capsules. Largest capsule has 54 mm in height and 31 mm in thickness. Capsule contains 2-3 embryos and numerous nurse eggs. Some egg capsules contained 2-3 young specimens (height 15.8, diameter 7.1 mm), which have well-developed calcareous shells.

The findings of the freshwater snail Boreoelona ehrmanni endemic to the Far East from the waterbodies of Yakutsk City are described. It is shown on the basis of dissections of snails and morphometric study of their shells that there are no statistically significant differences between the males and females of B. ehrmanni.

37 species of the land molluscs were identified in the material collected in 2002-2017,  many being earlier unknown from Zaporozhye region. In total 39 species of molluscs can be considered as reliably recorded from this region. The presence of some species is the result of anthropochory. This concerns first of all those land snails which have spread from the Crimea: Brephulopsis bidens, B. cylindrica, Phenacolimax annularis, Oxychilus deilus, Monacha fruticola, Xeropicta derbentina, X. krynickii, Eobania vermiculata, Helix lucorum. One species (Xerolenta obvia) was introduced to Zaporozhye region from the western part of Ukraine. The data obtained made it possible to clarify the current distribution of Helicopsis retowskii and Chondrula tridens martynovi over the territory of Ukraine.

A comparative analysis of the camera eyes of gastropod pulmonate molluscs Cepaea nemoralis and Cepaea hortensis was carried out on the basis of original and published data. It was demonstrated that the eyeballs and their main components in C. nemoralis and C. hortensis have more similarities in morphological and optical properties than in anatomical parameters.

At the end of the XX – beginning of the XXI century 85 species of the land molluscs of 49 genera and 25 families were reliably registered in the steppe zone of Ukraine. The highest species richness was recorded in the northern steppe subzone (79 species). The main centers of the species diversity are the Donetsk Upland (65% of the total number of species) and the western part of the Black Sea Lowland with the southern spurs of the Podolian Upland adjoining it (55%). The modern composition of the land molluscs fauna of the steppe zone is influenced by the proximity of the Caucasus (for the southeast of Ukraine), the Podolian Upland (for the North-Western Black Sea coast) and the Crimea (for the entire investigated territory). Anthropochory plays an important role in the formation of the land molluscs complexes in the steppe zone of Ukraine.

The locations of Boreoelona contortrix in the waterbodies of Western Siberia and Kazakhstan are reported as well as the data on morphology of shells and copulatory apparatuses of the species from different parts of its range. The interpopulation variation is considered. On the basis of anatomical and morphometric study, it has been shown that there are no statistically significant differences between males and females of B. contortrix. Some problems related to taxonomic diagnostics of the Boreoelona snails are discussed.  

Morphological and optical properties of tentacular epidermis and cornea of the eyes of some species of terrestrial gastropod pulmonate molluscs were studied and their evolutionary transformations were estimated. It was demonstrated that all examined properties of tentacular epidermis and cornea of those species are typical for terrestrial pulmonates. In the course of evolution tentacular epidermis of terrestrial pulmonate molluscs was modified to less extent than cornea, and both these structures underwent minor changes in comparison with analogous structures of the eyes of marine prosobranch molluscs.

The new data about seasonal dynamics of species composition, abundance and biomass of molluscs on soft sediments in the corner part of the Sevastopol bay were analyzed. 24 species of molluscs were recorded in 2006-2007. The microdistribution of Mollusca at stations depends on salinity. The trophic structure of molluscs’community was determinated and includes 6 trophic groups.

Only four species of the family Cancellariidae had been reported from the Arctic. However, known distribution of three of them had been limited by the extreme north of the eastern Atlantic so far. The present paper describes findings of Admete contabulata Friele, 1879 from the Barents and the Kara seas and Iphinopsis inflata (Friele, 1879) from the Pacific part of the Arctic Ocean. Lectotype for Admete contabulata is here designated.

Study of the reproductive tract of Helix pseudomiara Bavay et Dautzenberg, 1908, formally attributed to the genus Trachia, and its comparison with other anatomically studied species of the genus, made it necessary to reconsider the taxonomic structure of the taxon. It is shown that four species, whose anatomy is known, belong to four genera, differing both conchologically and anatomically. Descriptions and diagnoses (based on their type species) of genera Trachia Martens, 1860 (type species Helix asperella Pfeiffer, 1846), Bellatrachia gen. nov. (type species Helix pseudomiara Bavay et Dautzenberg, 1908), Pseudotrachia gen. nov. (type species Helix vittata Müller, 1774), and Neotrachia gen. nov. (type species Helix duporti Bavay et Dautzenberg, 1908) are presented.

This paper summarizes the mechanisms behind the patterning of the intra-population spatial arrangement of the land snail Vallonia pulchella (Müller, 1774) in terms of edaphic and vegetation properties. The molluscs were collected from a regular grid in recultivated soil (the research station of Dnipro State Agrarian and Economic University, Pokrov, Ukraine). As predictors of the snail population abundance, spatial variables were used, as well as edaphic and vegetation indices. It is shown that V. pulchella to prefer microsites characterized by higher soil electrical conductivity, which contain larger aggregate fractions with low mechanical impedance and the low temperature at the depth of 0-10 cm, with a more developed dead plant layer, low-light and low hygromorph and heliomorph index values of the vegetation.

Three new species of the genus Stenosemus collected near Fiji and Solomon Islands of the central Pacific are described here. Stenosemus fijiensis sp. nov. from Fiji differs from the congeneric species by a unique sculpture of the central areas of tegmentum, consisting of triangular pits and light brown spots on valves. S. philippei sp. nov. and S. solomonensis sp. nov., both from the Solomon Islands, differ from other the species of the genus by having a head of major lateral tooth of radula bicuspidate with small outer denticle, shape and sculpture of dorsal spicules and sculpture of tegmentum.

Bela arctica A. Adams, 1855 has a complicated and confusing taxonomic history. Grant and Gale [1931] considered “Defrancia viridula Fabricius” Møller, 1842, Bela kobelti Verkrüzen, 1876, “Bela viridula Møller” G.O. Sars, 1878, and Lora tenuilirata cymata Dall, 1919 as its synonyms. It is demonstrated that Propebela arctica sensu Grant and Gale is a group of six species belonging to four genera. It is proposed to consider the following species as separate: Propebela arctica (A. Adams, 1855); Curtitoma finmarchia (Friele, 1886) comb. nov. [=“Defrancia viridula Fabricius” Møller, 1842]; Curtitoma georgossiani sp. nov. [=“Bela viridula Møller” G.O. Sars, 1878 (part)]; Granotoma kobelti (Verkrüzen, 1876) comb. nov., Granotoma tumida (Posselt, 1898) comb. nov. [=“Bela viridula Møller” G.O. Sars, 1878 (part)], and Obesotoma cymata (Dall, 1919). In addition, in this work for the first time Curtitoma livida comb. nov. is recorded from Russian waters.

On the Kugitangtau Ridge (western part of Pamiro-Alai mountain system) 16 specimens of a new species of molluscs referring to the nominative subfamily of the Bradybaenidae family have been found. The new taxon differs from all other species of this subfamily by total absence of all additional organs of female section of the reproductive tract (stylophore, additional sac, mucus glands, supraatrial bladder), bean- shaped short penis, and thick-walled penis sheath that attached at both proximal and distal ends. On the base of these characters the illustrated description of a new monotypic taxon Kugitangia hatagica Schileyko, Pa- zilov et Abdulazizova, gen. et sp. nov. is presented. Conchologically the new species does not differ reli- ably from Fruticicola fedtschenkoi and differs from Fruticicola perlucens mainly by the presence of fine granulation on the embryonic whorls.