Volume 27

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.

 In accordance with the taxonomic system adopted in Russia and used also in Estonia, the largest local forms of pea clams (Sphaeriidae) have been treated as two species, P. amnicum and P. inflatum. The aim of the study was to clarify if P. amnicum and P. inflatum are separate species. Populations of both forms from Estonia were analysed genetically and morphologically. Analysis of the COI and ITS-1 gene fragments revealed that these two forms were genetically indistinguishable. Although there were statistically significant differences in the relative proportions of the shell between their typical individuals, there occurred also intermediate values. Consequently, P. inflatum cannot be considered as a separate species and should be treated as an ecological variety of P. amnicum that inhabits mainly a characteristic sandy substrate.

Development of the larval and juvenile shells of the White Sea bivalve Zirfaea crispata has been studied. The main stages of shell development from D-stage to early juveniles were described. The formation of larval hinge, consisting of two small teeth on the left valve and two teeth of different size on the right valve was observed. The complex shape of the large tooth on the right valve was noted at the pre- metamorphosis stages. Development of a structure, typical for certain Pholadidae – an articular connection on the ventral edge of the shell was recorded. This connection consists of a rectangular tooth on the right valve and a depression, flanked by small projections, on the left valve. The ventral connection starts to form at the larval size of 300 µm and becomes fully formed prior to metamorphosis. After metamorphosis the ventral connection does not disappear, but continues to grow with the growing edge of dissoconch. The role and functional importance of this structure in Zirfaea is discussed.

New findings of four gastropod species: Melanella laurae, Hemiaclis ventrosa (family Eulimidae), Chrysallida sublustris and Odostomia acuta (family Pyramidellidae) are described. O. acuta was previously confused by Russian authors with H. ventrosa, distribution of both species in the Barents Sea is limited by the coastal waters of Finmark and Murman. M. laurae and C. sublustris were found for the first time in the adjacent to the Barents Sea parts of the Arctic Ocean.

Based on the study of the reproductive tract of Metafruticicola occidentalis Subai, 1999, it is shown that the species belongs to a new subgenus (Elbasania subgen. nov.). For comparison, the anatomy of seven species of the genus Metafruticicola (including type species) has been studied. It is shown that the species of this genus are clearly distinguished from one another by the structure of the copulative apparatus (mainly of penial papilla). Comparison of the genus Metafruticicola with the representatives of other genera of Hygromiidae that have no accessory organs on the vagina is conducted. We suggest that the genus Cyrnotheba Germain, 1929 may belong to the subfamily Metafruticicolinae while the genus Caucasocressa does not belong to this subfamily and might be included in the subfamily Monachainae. Problems of taxonomic structure of the genus Metafruticicola briefly discussed.

In the paper of Merkuljev A.V. 2017. “Taxonomic puzzle of Propebela arctica (A. Adams, 1855) (Gastropoda, Mangeliidae) – six different species under single name”, published in vol. 27(1): 15-30 the misprint has been found. On p. 26 in the caption to Fig. 5, the 9-th line from the bottom, instead of “C. georgossiani sp. nov. C. The holotype, ZIN 21768/1” read “C. georgossiani sp. nov. C. Paratype, ZIN 51254/2.”

Limax flavus Linnaeus, 1758 not previously recorded in Central Asia was found in Uzbekistan. The total number of adventitious species in Central Asia is 12; six species are migrants from Asia (Caucasus); six from Europe. Nine species were found before 1990, while three after 1991. Of these seven species are slugs (58%); nine of adventitious species are kolonozoids, three – epecozoids.

In 2015-2016 land molluscs from 43 localities in Ararat Region, Vayots Dzor Region and Kotayk Region as well as in Yerevan were investigated. The introduced species Monacha fruticola and Oxychilus cf. filicum were first discovered on the territory of Armenia. One new locality of the rare species Orculella ruderalis, listed in the Red Book of Armenia, was found. The some pecularities of the intraspecific variability of the shells of O. ruderalis and Pseudochondrula tetrodon were described.