Volume 27

Three species, attributed to buccinid genus Plicifusus, had been previously known from the Arctic: Plicifusus kroeyeri (Møller, 1842), P. johanseni Dall, 1919, and P. rodgersi (Gould, 1860). Study of museum collections and recently obtained material from the Laptev and East Siberian seas resulted in discovery of Plicifusus maehirai Tiba, 1980, previously known from the Northern Pacific, and Plicifusus sp., which probably belongs to an undescribed species. P. johanseni has been found in the Russian waters for the first time. Lectotype of P. johanseni has been designated.

On the basis of dissections and shell measurements we studied sexual dimorphism in shell shape in Parafossarulus manchouricus (Gerstfeldt in Bourquignat, 1860) taken from the bay of the Bira River (Russian Far East). It is shown that there are no statistically significant differences in shells of males and females in P. manchouricus.

In 2015-2016 land molluscs from 48 natural and anthropogenically transformed localities in Syunik Region of Armenia were investigated. The analysis of our and literature data gave the possibility to draw up a species list of land molluscs of Syunik Region, which includes 78 species. Two forms with unclear taxonomic status are described: Stenomphalia sp. and Chondrula cf. sunzhica.

The population structure of the terrestrial mollusc Brephulopsis cylindrica (Gastropoda, Pulmonata, Enidae) in the native area (Crimea Peninsula) and out of its borders (two adventive groups in the city of Belgorod) was studied on the basis of conchometric characteristics and analysis of polymorphic allozyme loci. For all the morphometric parameters statistically significant differences were found between the studied groups. In all studied populations a high level of intrapopulation genetic variability was revealed (Fit = 0,401). At the same time, the considerable variability of the conchological parameters and the high level of allelic polymorphism at a number of loci identified in adventitious colonies create the prerequisites for successful adaptation to new conditions and further expansion of the species range in urbanized areas. 

Morphological properties of the granules of the screening pigment in the retinae of camera eyes of gastropod mollusks with different light preferences were studied. It was demonstrated that the pigment granules of mollusks can differ by color and size but do not differ by structure, electron density and form. Light conditions of mollusks’ habitats can influence on the amount of the screening pigment, which in its turn does not affect resolving ability of the eyes.

Two doubtful cases of species name replacements in the family Lymnaeidae Rafinesque, 1815 (pond snails) proposed in 1990–2000s are discussed. These are: Radix labiata (Rossmäßler, 1835) vs. R. peregra (O.F. Müller, 1774), and Stagnicola fuscus (C. Pfeiffer, 1821) vs. S. vulneratus (Küster, 1862). It is shown that in both instances the name alterations were not based on the conclusive evidence and thus seem to be proposed without substantial reasons. I argue that the name Radix peregra cannot be ruled out and replaced by R. labiata. The type series of the latter has been identified in collection of the Natural History Museum of Vienna and it is shown that R. labiata is a junior synonym of R. balthica (Linnaeus, 1758). The lectotype of Limnaeus pereger var. labiatus Rossmäßler, 1835 is designated. The resurrection of the species name Limnaeus fuscus (Pfeiffer, 1821) for application to a certain species of Stagnicola is also very doubtful since this name must be treated as a nomen dubium, and any taxonomic interpretation of it is inevitable based on more or less reliable hypothesis, not on the total evidence. The replacement of S. vulneratus by its alleged senior synonym adds little to our knowledge on lymnaeid taxonomy and evolutionary relationships. It is desirable that the nomenclatorial principle of priority must not be applied to nomina dubia.

New data on the record of synanthropic species of slugs Limacus flavus and Krynickillus melanocephalus in Belarus are analyzed. It is assumed that the penetration of these species into the territory of Belarus occurred from their natural habitats anthropochory way together with the imported vegetable products.

Acrotoma (Castelliana) likharevi sp. nov., Acrotoma (Castelliana) reshaviensis sp. nov., and Micropontica (Baleopsina) olgae sp. nov. are described from the Bzyb Mountains of Abkhazia. The taxonomic position, relation to congeneric taxa, and zoogeographical significance of the new taxa are discussed.