Diet of European freshwater pearl mussels Margaritifera margaritifera (Mollusca: Bivalvia: Unionoida) in small river (Republic of Karelia, Russia)

The freshwater pearl mussel Margaritifera margaritifera (Linnaeus,1758) is endangered in Europe and is now listed in the Red Data Book of many countries and regions. The diet of the species in the Syskyänjoki River (a tributary of Lake Ladoga) has been studied. The contents of the intestine generally correspond to the composition of seston, and include organic detritus, filamentous and unicellular algae, fragments of invertebrates and macrophyte tissues mixed with silt and sand. The total biomass of the intestinal contents of varied from 0.8 to 30.6 mg per organism (absolutely dry weight). Margaritifera margaritifera consumes a wide range of particles, from 0.5 μm3 (bacteria and unicellular algae) to 200 000 μm3 (fragments of invertebrates and macrophyte tissues). About 90–95% (by volume) of the intestinal contents was consisted by fine organic detritus. The food composition did not differ significantly for mollusks of different sexes and size. In the intestinal contents, 63 taxa of algae were identified. The number of algal species in the content of one intestine varied from 3 to 17, with their abundance from 250 to 9560 cells per organism. The most abundant and constant in the contents of the intestines are unicellular algae. Diatoms are the most diverse, they make up 50.8% of the total number of species.

First Paleocene Lepidozona (Mollusca: Polyplacophora: Chitonida) from Ukraine

A new species Lepidozona luzanovkensis sp. nov. from Paleocene deposits of Ukraine is described. This find is much earlier than the known finds from the late Eocene or Early Oligocene, which increases the age of the genus Lepidozona Pilsbry, 1892 by several million years.

Remains of the Baikal yak (Poehpagus mutus baikalensis N. Verestchagin, 1954) from Late Pleistocene localities of Southern Siberia

136 bones of the postcranial skeleton and a part of the skull of a female Baikal yak (Poephagus mutus baikalensis N. Verestcthagin, 1954), originating from 18 cave locations and open-type Paleolithic sites in Altai-Sayan, Transbaikalia and Central Mongolia were examined. The material includes 38 metacarpals and 9 metatarsals of the yak. Morphometric differences in the structure of the postcranial skeleton of the yak and the bison (Bison priscus Bojanus, 1827) were revealed. The body size of the Baikal yak significantly exceeded that of the wild Tibetan yak (Poephagus mutus Przewalski, 1883). The largest representatives of P. m. baikalensis inhabited the Altai Mountains. In most of the sites, located in the mid-mountain landscapes of Southern Siberia (with absolute heights of 500–700 m), only a few remains of the Baikal yak were found, accounting for 0.01% to 1–2% of the number of megafauna remains. Most likely, herds of yaks did not live here permanently, but appeared only sporadically, during seasonal migrations. In higher mountainous areas (from 1000–1500 m) of Gorny Altai and Khangai Mountains in Central Mongolia, the proportion of the remains of the Baikal yak increases significantly – up to 16–22%. Like the contemporary P. mutus, the Pleistocene yak found its ecological optimum in the high-mountainous parts of ridges and mountain plateaus, dominated by cold, dry mountain-steppe landscapes with herb-grass vegetation and a small amount of snow. During the periods of cryochrones, the area of P. m. baikalensis apparently expanded significantly, incorporating the adjacent foothill territories. During the periods of thermochrones, it was most likely limited to the high-mountainous areas of the mountain uplifts of Southern Siberia.

Herpetofauna of the Maninjau caldera, West Sumatra, Indonesia, with special account to geckos

The field surveys were conducted in the Maninjau Lake region, Sumatera Barat, Indonesia, in February 2020, mainly on the north-eastern slope of the Maninjau caldera at 450–600 m a.s.l. The slopes of the Maninjau caldera are naturally covered by a tropical rainforest that remains quite undisturbed from an altitude of 900 m up to the crater ridge. Natural vegetation of the northern and eastern slopes at altitudes from 450 and 500 to 600 m a.s.l. is replaced by rice plantations or mixed forest gardens. The typical habitat consisted of an evergreen broad-leaved forest on the slopes along a mountain creek and around a waterfall. Herein, we report 11 new species records for the Maninjau caldera; 9 new species records for Agam Regency; 3 new species records for Sumatra and Indonesia and 1 species of Cnemaspis Strauch, 1887 new for science. The morphology of rare and poorly known species of the bent toed gecko, Cyrtodactylus agamensis (Bleeker, 1860) is described for the first time. A high diversity of Cyrtodactylus Gray, 1827 occurs in Indochina and on the Thai-Malay Peninsula (150 species) but only six species in Sumatra. The Malay-Indochinese genus Cnemaspis has a recent spurt of diversity and now reaches eight species in Sumatra and only one species reaches Java. Current gecko diversity in Sumatra comprises 29 species in eight genera. The level of endemism level in geckos is very high and reaches 48%. The herpetofauna of Maninjau Caldera includes 26 amphibian and 46 reptile species. The faunistic core of the West Sumatran herpetofauna consists of Malay-Sundaic, Sumatran endemic, Sunda-Indochinese and widely distributed Oriental elements. The West Sumatran herpetofauna is characterized by the presence of a mutual species with Indochina, Malaysia, east India, Myanmar, the Andaman and Nicobar islands and Sri Lanka, often with disjunction in the huge territory of Indochina; species with continuous distribution from the Indian subcontinent to Papua and Oceania; and generalist species with wide pan-Indopacific distribution.

Evaluation of the composition of essential fatty acids in the tissues of rainbow trout (Oncorhynchus mykiss) grown in closed water supply units

Recently, the task of artificial cultivation of especially valuable fish species in aquaculture has become more and more urgent. The value of salmon fish, and in particular rainbow trout Oncorhynchus mykiss (Walbaum, 1792) available for breeding, is largely determined by the high content of biologically active essential and polyunsaturated fatty acids of the group ω-6 and ω-3, necessary for vital activity and not synthesized by the human body. Since the natural stocks of many popular fatty fish have decreased, farmed fish can help meet consumer demand for this product. Based on this, the assessment of the content of the main ω-6 and ω-3 fatty acids in the fat of rainbow trout grown in closed-loop water supply installations (USV) was made. The fat was extracted from the fish by thermal method with further distillation by supercritical fluid extraction on the SFT-150 unit. The ratio of fatty acids in the fish oil sample was determined using the Chromatek-Kristall-5000 M hardware and software complex. The results obtained were compared with the standard for salmon fish oil “Aquaculture products” and “Wild fish”. It is established that trout cultivated in the UZV in the Penza region, in terms of the content of the main essential fatty acids, is not inferior to the quality indicators of the standard in terms of the requirements for salmon fish of “Aquaculture products”. In fish, all essential fatty acids are present in sufficient quantities, the ratio of ω-6 to ω-3 is 2.6:1, which indicates a high nutritional value of the product and allows it to be used in human food to provide the body with essential fatty acids, as well as a raw material for obtaining therapeutic and preventive products.

Review of the current objectives and modern approaches to studying extant and extinct shrews (Soricomorpha: Soricidae) investigation: the origin of the modern subfamilies and diversity of Crocidosoricinae

The current review is devoted to topical issues of the origin of modern shrew’ subfamilies Soricinae Fischer, 1817 and Crocidurinae Milne-Edwards, 1868 (Soricomorpha: Soricidae), as well as to the consideration of the possibility of using morphological analysis to search for ancestral groups of modern soricine and crocidurine shrews within the extinct subfamily Crocidosoricinae Reumer, 1987. The data on the taxonomic composition of the Crocidosoricinae subfamily and the preliminary results of a comparative analysis of the Neogene shrews Miosorex Kretzoi, 1959 and Shargainosorex Zazhigin et Voyta, 2018 (Crocidosoricinae) shrews with the representatives of Soricinae and Crocidurinae according to the shape of the first upper molar M1 are presented as an example to substantiate urgent problems in this area. The problem of relations of molecular and morphological data are discussed using individual groups as examples. Modern approaches of geometric morphometry are described, which together with phylogenetic data allow assessing the expression of the phylogenetic signal when analysing the shape of morphological structures. Possible prospects for the practical application of these approaches for the study of fossil material and the search for ancestral lineages of modern shrews among Crocidosoricinae are described.

New anomalies and pathologies in the caudal region of the lizard’s axial skeleton

Currently, more than 58 skeletal anomalies and pathologies are known in the recent Squamata reptiles. In this paper, eight pathologies of a complex nature are described in Agamidae and Lacertidae: Paralaudakia caucasia (Eichwald, 1831) and Lacerta agilis Linnaeus, 1758. Description of tail pathologies was carried out based on the analysis of X-ray images and on the results of computer microtomography. In the specimen of P. caucasia (ЗИН 19116.1) complete ablation of the caudal vertebra was revealed, which provoked the detachment of chevron and the proliferation of soft tissues. In some Agamidae, after pseudoautotomy, partial ablation of the caudal vertebra occurs to promote wound healing. Complete ablation of the distal caudal vertebra has not been previously reported in literature. In females of L. agilis, deformation of the right transverse process of the vertebra with “false bifurcation” without the formation of a cartilaginous tube (VOLSU 98.2), scoliosis, hematoma and callus on the cartilaginous tube were noted, as well as the absence of an autotomy plane in the postpygal vertebra (ZIN 31549). An unusual pathology in L. agilis (ZIN 31549) is the absence of an autotomy plane in the postpigal vertebra and of its anterior neural spine. The loss of the plane of autotomy during ontogeny is characteristic of some Iguanidae, but it has not been previously noted in Lacertidae. The described cases of anomalies expand the spectrum of known pathologies in reptiles.

On the Taxonomic Status of the Red Icefish Channichthys rugosus (Notothenioidei: Channichthyidae) from the Kerguelen Islands (South Ocean)

The presented work is the final part of the taxonomic revision of the Antarctic icefishes of the genus Channichthys Richardson, 1844 (Notothenioidei: Channichthyidae) from the Kerguelen Islands, the species composition of which was discussed until recently. Based on the morphological study of all available specimens from the ZIN and BMNH collections (including the holotype), a comprehensive redescription of the Red icefish Channichthys rugosus Regan, 1913 from the waters of the Kerguelen islands (South Ocean) was carried out, including external morphology, seismosensory system, gill apparatus, and axial skeleton. As a result, new diagnostic features of Red icefish were discovered and previously known ones were clarified, which made it possible to confirm the species validity. Comparison with other valid species icefishes was done. Channichthys rugosus differs from Ch. rhinoceratus Richardson, 1844 by a high anterior dorsal fin, the fin membrane of which reaches the apexes of its longest rays (does not reach in Ch. rhinoceratus), as well as a narrow and concave interorbital space (compared to the wider and flat one), by stronger granulation and a uniform reddish body color (dark spotted-marble in Ch. rhinoceratus). Channichthys rugosus differs from Ch. velifer Meissner, 1972 by the number of rays in the first dorsal fin (7–9 versus 9–12) and pectoral fin (18–20 versus 20–21), the presence of bone plaques in the proximal part of the medial lateral line (absent in Ch. velifer), and monochromatic reddish body coloration (spotted in Ch. velifer). Channichthys rugosus differs from Ch. panticapaei Shandikov, 1995 by the presence of only 1 row of gill rakers on the first gill arch (2 rows in Ch. panticapaei) and by light coloration (brownish-black in Ch. panticapaei).

Juveniles and larvae of eleven fish species collected from three countries of the Arabian Gulf and the Arabian Sea

The finding of larval and juvenile specimens from the Omani coast of the Arabian Sea and the Arabian Gulf waters of Saudi Arabia and Iraq is reported for the first time. Based on available information, one larva was a leptocephalus, Conger sp. (family Congridae) and one larva of an acronurus stage belonging to the genus Acanthurus (family Acanthuridae). Also juveniles of the following families are included in the present study: Clupeidae – Tenualosa ilisha (Hamilton, 1822) and Nematalosa sp.; Dactylopteridae – Dactyloptena orientalis (Cuvier, 1829); Gobiidae – Acentrogobius sp.; Bothidae – Arnoglossus aspilos (Bleeker, 1851); Scatophagidae – Scatophagus argus (Linnaeus, 1766); Sparidae – Acanthopagrus arabicus Iwatsuki, 2013 and Sparidentex hasta (Valenciennes, 1830); Tetraodontidae – Lagocephalus sp. The discovery of the barred rather than spotted juveniles of S. argus collected from pure freshwater environment of the Shatt al-Arab River, Basrah, Iraq was remarkable; it raises questions whether there is more than one species within the nominal S. argus. For both larvae and juveniles of bothid flounders, the olfactory organ is a useful character for the examination of the developmental stage of the metamorphosing specimens. The occurrence of the different early life history stages of fishes from the three Arabian countries shows the needs them to be studied further so that inferences about the areas and periods of spawning and development of these fishes can be made more accurately.

Differentiation of communities of macroinvertebrates and cottoid fish associated with methane seeps of different bottom landscapes of Lake Baikal

The paper presents the results of the study of communities of macroinvertebrates and cottoid fish inhabiting methane seeps of Lake Baikal. For the analysis, we used video surveillance and collection of animals carried out with the help of "Mir" deep-water submersible, as well as NIOZ-type box-corer samplers from the board of a research vessel. Posolskaya Bank and Saint Petersburg methane seeps are located in different basins (southern and middle) and at different depths (300–500 m and ~ 1400 m), characterized by the different underwater landscapes (slope of underwater upland and hills formed by gas hydrates), by the structure of gas hydrates and their depth location in sediments, as well as the composition of microbial mats and communities of microorganisms of bottom sediments. Both seeps are characterized by bubble discharge of methane gas and the formation of highly productive communities of large invertebrates and cottoid fish on seep habitats. Seep animal communities consisted of species-depleted invertebrates and fish of the surrounding deep-water benthal of the Lake. We showed the similarities and differences in the composition of the faunas of two seeps, as well as the quantitative characteristics of taxonomic groups of macroinvertebrates and cottoid fishes. Obligate species have not been revealed on the methane seep Posolskaya Bank. For the methane seep Saint Petersburg, the gastropod species Kobeltocochlea tamarae Sitnikova, Teterina et Maximova, 2021 (Caenogastropoda: Benedictiidae) was designated as an obligate species; among bottom cottoid fishes, Neocottus werestschagini (Taliev, 1953) (Cottoidei: Abyssocottidae) had possible a transitional state to obligate. We presented the data on the assimilation by seep animals of mixed photo- and chemosynthetic food with different proportions of methane-derived carbon. A hypothesis has been substantiated that deep-water seep areas could serve as refugium for the preservation of endemic fauna during the Pliocene-Pleistocene glaciations of Lake Baikal.