The taxonomic status of Indoartemon vietnamensis Thach, 2020 is reassessed. The morphology of I. vietnamensis falls within the intraspecific variation of I. huberi (Thach, 2016). The similarities suggest that I. vietnamensis should be treated as a junior subjective synonym of I. huberi. Furthermore, a new subspecies of the genus Indoartemon is described from Chua Chan Mountain, Dong Nai Province, Vietnam. Indoartemon huberi chuachanensis subsp. nov., has oblique-heliciform shell with axially deflected last whorl, narrow and deep umbilicus, aperture with one strong parietal lamella and one small palatal lamella, slightly enlarged columellar fold along the columellar margin.
The present contribution expands the family Nierstraszellidae Sirenko, 1992 from a pair of deepwater species assigned to Nierstraszella Sirenko, 1992, to eight deepwater extant species in three genera, two of them new to science. These species are typically found on deep-sea sunken wood, implying a homologous ecological specialization shared for all species within the family. This systematic revision reflects a new understanding of a distinctive and ancient lineage within the chiton order, Lepidopleurida Thiele, 1909, whose revision has been challenged by inaccessible deepwater habitat of its members. Here we integrate both SEM and molecular studies, and recast Nierstraszellidae as one of multiple, mostly still unresolved, monophyletic lineages within Lepidopleurida. The type genus, Nierstraszella, is newly restricted to its type species, N. lineata (Nierstrasz, 1905), and two new genera are introduced. Rissochiton gen. nov. includes five similar species found in the Indo-West Pacific Ocean, all once grouped uncomfortably as Leptochiton rissoi (Nierstrasz, 1905). We distinguish type species R. rissoi by morphology and DNA from four other similar species, including R. formosaensis sp. nov. and R. quincuncialis sp. nov. A second new genus, Astrochiton gen. nov., has a neotropical distribution that is disjunct from other Nierstraszellidae. The two species, our selected type species, Lepidopleurus binghami Boone, 1928, from the Caribbean Sea and Gulf of Mexico, and A. incongruus (Dall, 1908) from the tropical Eastern Pacific. The results of a phylogenetic analysis, based on combined mitochondrial cox1 and 16S gene regions and corresponding to morphological affinities, support all three genera as independent lineages. Together, Nierstraszellidae is strongly supported as monophyletic relative to multiple included outgroups from across and outside of Lepidopleurida. Within Nierstraszellidae, a geographic split is evident between Indo-West Pacific and neotropical species. The molecular analysis also reveals a strong phylogeographic pattern within N. lineata. that is inconsistent with regular gene flow, hinting at cryptic species diversity. Together, our analyses support three genera that are united by features of the girdle, radula, and patterns of strong variability in the number of pores of aesthetes in the aesthete group. In contrast to other Lepidopleurida, members of Nierstraszellidae have a surprising amount of intraspecific variability in their tegmental sculpture, with some individuals having tegmentum granules in rows, while others have no trace of granules. Based on the number and location of the pores of the aesthetes, the Jurassic species Leptochiton shapovalovi Sirenko, 2013 is provisionally assigned to Rissochiton, which has implications for the antiquity of the family.
Gastropod mollusk Jujubinus exasperatus is recorded for the first time in the Black Sea off the coast of Crimea. A brief species diagnosis, photographs of the shells and live specimen in situ are provided. Previously, the species was listed for the fauna of Russia and the Black Sea based on literary sources, the reliability of the information discussed in this paper. The possibility of naturalization of J. exasperatus in the Black Sea ecosystem is considered. J. exasperatus is recognized as an accidental element of the Black Sea benthos.
Additional morphological data on Cerithidea tonkiniana Mabille, 1887, from Vietnam are presented based on extensive material collected across its currently known national range, including the Gulf of Tonkin and the central coast. This study provides the first SEM documentation of shell microstructure and radula for Vietnamese populations, and additionally presents a detailed description of the operculum of Cerithidea tonkiniana. Shell morphology exhibits moderate variation in size but stable proportions among populations, indicating marked morphological cohesion across a broad latitudinal gradient. The outer shell surface displays a compact commarginal microstructure with distinct growth increments consistent among examined localities. The radula conforms to the typical potamidid pattern and closely resembles that of C. sinensis, supporting their close affinity while retaining diagnostic differences. Updated distributional data refine northern locality records and confirm the species’ extension southward to Da Nang along the north-central coast. These results provide a detailed morphological reference framework for C. tonkiniana and facilitate more reliable identification of potamidid gastropods in mangrove ecosystems of the western Pacific region.
Three new species have been added to the formerly monotypic genus Liobaicalia Martens, 1876. We employed a combination of morphological, anatomical, and molecular approaches using mitochondrial COI gene, nuclear ATP-synthase alpha subunit gene intron (ATPase), and ITS1 spacer to delineate species boundaries between Liobaicalia stiedae (W. Dybowski, 1875), L. sidelevae sp. nov., L. karabanovi sp. nov., and L. riedeli sp. nov. The Liobaicalia species inhabit burrowing into sandy substrates in disparate regions of the ancient and/or recent deltas of the inflows to the south and central Baikal basins near tectonic faults where gases discharge happens. The genus Liobaicalia was not recovered as monophyletic based on current molecular-phylogenetic analyses based on mitochondrial COI data. We discussed discordance between morpho-anatomical and genetic traits, the possible origin of the Liobaicalia species, and the occurrence of scalariform shells in Baikal and non-Baikal gastropods belonging to different families.
The morphological features and ultrastructure of the hinge margin of the giant oyster Magallana gigas larvae, which were obtained from a nursery with the Black Sea broodstock and grown under optimal conditions, were studied. The paper presents scanning electron micrographs of disarticulated larval valves at different stages of development. In larvae at the D-veliger stage (2 days old, shell dimensions: 72×62 μm), as well as at the veliger stage (shell dimensions: 84×96 μm), the provinculum of the right and left valves consists of two anterior and two posterior teeth. We noted 2 to 3 teeth on the provinculum in both ”uneyed“ (H: 140–182 μm) and ”eyed“ velikonch larvae (H: 200–230 μm) on the anterior and posterior edges of the right and left valves. In pediveligers (H: 338–358 μm) there are two anterior teeth in the hinge margin of the right and left valves; the posterior teeth are reduced. We also determined logarithmic dependences of the hinge margin length (l, μm) on the length (L, μm) of the shell [ ; R2=0.904] and the maximum provinculum width on the shell height [ ; R2=0.8993] of larvae ranging in size from 72×62 to 322×358 μm. The morphological characteristics and provinculum ultrastructure of the reared larvae were compared with those of M. gigas larvae of Atlantic and Pacific origin. The article discusses the potential hybrid nature of the Black Sea broodstock.
The malacocomplexes studied in alluvial deposits of the Syra River valley formed during the Late Pleistocene to the Middle Holocene. They include 46 species from 15 families (Sphaeriidae, Bithyniidae, Valvatidae, Lymnaeidae, Physidae, Planorbidae, Carychiidae, Succineidae, Cochlicopidae, Valloniidae, Vertiginidae, Discidae, Pristilomatidae, Gastrodontidae, Hygromiidae). Most of the registered freshwater mollusc species tend to inhabit either permanent, weakly flowing or stagnant waterbodies that are overgrown with macrophytes or with signs of swamping; or temporary drying ponds and swamps. Species composition of terrestrial snails indicates the presence of highly humid conditions in their habitats. Perhaps there were temporary swampy water bodies at the site of the modern riverbed and the composition of the fossil malacofauna along with ecological preferences of found mollusc species represents the specific features of the palaeoecological conditions of past ages.
The generic name Cryptobranchia Middendorff, 1851 is a junior objective synonym of Lepeta J.E. Gray, 1842. Designation of Patella caeca var. concentrica Middendorff, 1848 as a type of Cryptobranchia is invalid. For two species previously assigned to the genus Cryptobranchia [Lepeta concentrica (Middendorff, 1848) and Acmaea kuragiensis Yokoyama, 1920], the new generic name Cryptolepeta gen. nov. is proposed.
A description of Turanena gissarika sp. nov. from the Gissar Ringe is presented. Conchologically, the new species is most similar to T. cognata, but anatomically it differs in having a tubercle-like swelling on the opposite side of the caecum.
Age-related variability of the shell valves and radula in two species of the genus Callistochiton and one species of the genus Ischnochiton is discussed based on the photographs obtained with a scanning electron microscope. Particular attention is given to the shape and sculpture of the valves, as well as the shape and number of teeth in the transverse row of the radula. It is shown that even such a key feature of the genus Callistochiton as radial ribs on the head, intermediate and tail valves is absent at the early stages of development and appears only when the body length reaches 4–5 mm. The results of studying age-related variability are of great importance for the taxonomy of both recent and fossil mollusks.
The response of mollusk communities to radioactive contamination in natural freshwater ecosystems remains understudied. We have analyzed the data on species composition of bivalve and gastropod mollusks inhabiting the «Mayak» Production Association (PA) (Russia, Chelyabinsk Region) special industrial reservoirs (R-3, R-4, R-10, R-11, R-17). These waterbodies have the status of facilities of atomic energy industry (the “atomic heritage”) and are used as storages of liquid radioactive waste. The Shershnevskoye Reservoir (Chelyabinsk City, Russia), a waterbody with background activity concentration of anthropogenic radionuclides, has been studied as a control site. Radioactive contamination has led to chronic exposure of freshwater mollusks. The dose rate ranges were as follows: 6–14 mGy/day for reservoir R-11; 16–40 mGy/day for reservoir R-10; 37–73 mGy/day for reservoir R-4; 49–72 mGy/day for reservoir R-3; 1,270–2,370 mGy/day for reservoir R-17. It has been found that chronic radiation exposure leads to a decrease of mollusk species diversity. 21 species of bivalves and 35 species of gastropods were registered in the control waterbody. In radioactively contaminated sites, a sharp decrease in species diversity has been observed. For example, in reservoir R-11, 7-fold decrease in the number of bivalve mollusk species and 2-fold decrease in the number of gastropod species as compared with the control reservoir have been recorded. In R-10 and R-4, the number of bivalve species was reduced 20-fold and the number of gastropod species was reduced 5- and 9-fold, respectively. In R-3, no bivalves were registered, and the number of gastropod species was reduced 6-fold. No mollusks were detected in R-17. Among all hydrobionts, pelophilous bivalves of the family Sphaeriidae, as well as gill-breathing snails (Gastropoda, Caenogastropoda), whose life cycle is associated with bottom sediments, are the most vulnerable to the effect of chronic radiation exposure.
The new species, Vallonia yakutica sp. nov. is described from the central part of the Republic of Sakha (Yakutia). The population lives on the edge of the forest of larch (Lárix sibírica ldb.), and birch (Betula pendula Roth.) trees, with various herbs. The presence of herbs is necessary for the habitat of Vallonia yakutica sp. nov. which feeds on their fallen leaves. The maturity of the snail is achieved in two years. The differences between the new species from the morphologically most close Vallonia kamtschatica Likharev, 1963 are discussed.
A new species of the bythiniid snails, Opisthorchophorus confusus Andreeva sp. nov., is described based on molecular and morphological data. A COI phylogeny inferred on the material of newly obtained sequences and those accessible through the GenBank has releaved the species distinctness of O. confusus sp. nov. as well as the full genus status for Codiella Monterosato, 1894 and Opisthorchophorus Beriozkina et Starobogatov, 1995. The genus Pseudobithynia Glöer et Pešić, 2006, on the other hand, has been revealed as paraphyletic, but the proper status of this taxon is unclear, since no genetic information is available on its type species distributed in Iran. The new species is widely distributed in Russia; its genetically confirmed localities are situated in Krasnodar Krai (south of European Russia) and Western Siberia. Based on morphologically identified specimens, the range of O. confusus sp. nov. embraces European Russia, southern parts of Western and Eastern Siberia as well as Northern and Central Kazakhstan. The new genus is conchologically and molecularly distinct from the species Opisthorchophorus troschelii (Paasch, 1842) [known also as Bithynia transsilvanica Bielz, 1853]. The nomenclatural issues related to the name Bihynia troschelii are discussed.
For the first time in the Russian waters of the Sea of Japan, the tropical-subtropical species of bivalve mollusk, Musculus cupreus (Gould, 1861), was found. An illustrated description of shells, synonymy, information on distribution and ecology are provided. An assumption is made about the probable introduction of M. cupreus into Peter the Great Bay.
This paper provides first reliable data on the finding of the bivalve mollusc Thracia septentrionalis in the Sea of Japan. A live specimen (L = 24.4 mm) was collected in June 2003 in Peter the Great Bay at a depth of 70 m on medium-grained sand. The data on geographical distribution and ecology of the species in the northern Pacific Ocean are summarized. The validity of Thracia seminuda Scarlato, 1981, previously synonymized with T. septentrionalis, is confirmed. Diagnostic differences between these species are specified and illustrated.
A new deep-water species Stenosemus formosaensis sp. nov. collected in the northeast of the South China Sea southwest of Taiwan is described. From other species of the genus Stenosemus the new species is distinguished by dark olive stripes radially arranged on head valve and lateral areas and longitudinally on pleural areas, and also by the arrangement of grooves of different tegmentum zones.
In the Kherota River (Russian Black Sea coast), freshwater mussels not previously known in the area were discovered and morphologically identified as Unio gontierii Bourguignat, 1856 (Bivalvia: Unionidae). The mussel species identity was verified by analysis of the mitochondrial gene sequence encoding cytochrome c oxidase subunit I (COI). The diversity of the eight studied microsatellite loci in the studied sample was rather high (the average number of alleles per locus was 4.75, the observed heterozygosity was 0.50±0.08). The aforementioned facts, in conjunction with the substantial distribution of the bitterling Rhodeus colchicus Bogutskaya et Komlev, 2001 along the Russian Black Sea coast, whose larvae develop in the bivalves, indicate that Unio gontierii is an indigenous inhabitant of the Russian part of the Caucasian coast and not a recently human-introduced species.
An impressive, medium-sized new camaenid species, Ganesella tamchuc sp. nov., is described from Hà Nam Province, northern Vietnam. Ganesella tamchuc sp. nov. is similar to Ganesella emma (Pfeiffer, 1863) in its general shell coloration pattern but differs by having a smaller shell size; three distinct color belts on the shell surface, including a white belt at the keel and two dark brown belts situated above and below the keel; strong radial ribs that protrude from the shell surface and also present at the umbilicus and within the aperture; a distinctly keeled last whorl that becomes weak behind the peristome; and a widely open umbilicus through which all whorls are visible.
The results of the experimental study of food preferences of Arion vulgaris in the conditions of Central Russia are presented. Fifty-five native and alien plant species from 22 families were used in the experiment. A. vulgaris causes the greatest damage to the Apiaceae and to a lesser extent to the Polygonaceae, Onagraceae and Ranunculaceae. Assessment of trophic preferences of the A. vulgaris showed a wide food plasticity, providing high adaptability of this species.
The snails of the genus Helicopsis belong to steppe species, many of which are listed in the protected lists of European countries. In this work, based on the sequencing of the COX1 mitochondrial gene, the species belonging to eight populations of snails from the genus Helicopsis living in the south of the Central Russian Upland have been identified. These populations were assigned to H. lunulata, H. filimargo, and H. hungarica, and the average genetic distance between them was 0.11±0.01. Next, we analyzed the variability of seven microsatellite (STR) loci developed by us for H. lunulata in one population of H. filimargo, one population of H. hungarica and five populations of H. lunulata in the south of the Central Russian Upland. Both loci specific to H. lunulata and universal for all studied species have been identified. In H. lunulata, six STR loci turned out to be polymorphic and had from 2 to 11 alleles per locus. A total of 28 alleles were identified at all loci in H. lunulata, 14 of which were private and did not occur in more than one population. Molecular Dispersion Analysis (AMOVA) confirmed the high genetic differentiation of H. lunulata populations (Fst=0,425). At the same time, the genetic diversity of H. lunulata in the study area based on STR loci turned out to be higher than in the case of using allozyme loci. The structure of genetic variability calculated on the basis of STR loci turned out to be less pronounced compared to the use of allozyme loci as genetic markers (Fst=0,700). All this confirms the greater selective neutrality and greater diversity of microsatellite loci compared to allozymes. The data obtained can be used to assess the genetic diversity of H. lunulata. populations.
