Contents of Proceedings of the Zoological Institute

We conducted a comparative analysis of qualitative composition of the Buzuluk Pine Forest avifauna, mainly based on data collected by ornithologist E.P. Knorre for the period 1928–1941, and modern observations done between 2000 and the present. Retrospective data were obtained from the now-defunct Buzuluk Bor Reserve with an area of 10 503 hectares (now Borovoye-Opytnoe Forestry in the Orenburg Province). Present-time personal avifaunistic observations (using standard methods with referring to literature sources) were carried out on an area of 49 000 hectares, both in Borovoye-Opytnoe and in several adjacent forestries that were part of the Buzuluk Bor National Park within the Orenburg Province. Comparing the historical and current bird lists, we used a relative assessment of changes in the composition of various bird groups based on the observed and expected frequencies according to the χ² test. Long-term data on average annual temperatures and precipitation from a nearby state weather station were also used. As a result, it is shown that by now the list of birds of E.P. Knorre decreased from 153 to 109 species (28.8%). When comparing by orders, the water birds were found to be the most affected group. The number of species in orders Podicipediformes, Ciconiiformes, Gruiformes decreased by 80–100%, and it dropped by more than 50% in orders Anseriformes and Charadriiformes. There was also a slightly smaller decrease in the number of species in orders Falconiformes and Strigiformes – by about 40%. An assessment of the relative changes in various bird groups from Knorre’s list based on expected and observed frequencies showed significant differences in the portion of avifauna associated with water. It decreased between 23.5% and 9% in the group ‘Limnophiles’ (χ² = 11.7, df = 1, p = 0.0006) and between 24.8% and 9% in the group of orders represented by waterfowl and waterbird species (χ² = 13.4, df = 1, p = 0.0002). The change in the portion of birds of prey was statistically non-significant. The same portion assessment method did not statistically confirm the decrease in the rest ecological and order groups. Comparison of groups by occurrence status found no significant changes in the portions of all groups of birds in the past and present, but the largest reduction was recorded in the group of migrating species. The portion of migrants decreased from 8.7% to 3.0% (χ² = 3.2, df = 1, p = 0.07, Yates corrected χ² = 2.2, p = 0.1). A dramatic decline in group of bird species associated with wetlands was suggested to be due, among other factors, to the progressive desiccation of the Buzuluk Pine Forest, as E. Knorre himself wrote in his report. The ongoing aridization of the climate, as shown by the graph of average annual air temperatures, has been taking place since at least the 20s of the twentieth century and led to the drying-up of wetlands, and also to migration of groundwater to deeper horizons. The emerging trend towards a reduction in the portion of migrants could be explained by the fact that a number of migratory bird species, mainly ducks and waders, disappeared in the study area, and several other migrants began breeding species. In addition, large-scale fires and logging led to formation of burned wasteland areas inside the forest at the beginning of the twentieth century and also probably contributed to fragmentation and desiccation of this biome.

The complexity of the structure of the dental surface of the first lower molar (m1) of mainland and island populations of the reed vole Alexandromys fortis (Büchner, 1889) was assessed using two different methods. Using the traditional approach and methods of geometric morphometry (GM), the morphological variability of the anteroconid m1 of this species of the mainland (the south of Primorsky Krai) and the islands of the Peter the Great Gulf was analyzed. The traditional approach was based on describing the folding of the occlusal surface using three features: 1) folding of the lingual side of the anterior unpaired anteroconid loop (AC); 2) the shape of the labial side of the AC; 3) the shape of the fourth lingual reentrant angle. On the mainland part of the species' range, the highest occurrence was shown by morphotype III-C-a, which also predominated in the Late Pleistocene samples of the species in Primorye. The research revealed increased morphotypic diversity in island populations of the reed vole, which is probably due to the phenotypic and genotypic characteristics of the founders of island populations, as well as inbreeding, which can cause the release of hidden diversity and an increase in the number of rare morphotypes. The most numerous morphotype on the De Livrona – Durnovo Islands was II-C-a, rare for the mainland. In general, the most complex forms are present on the islands. Using a geometric morphometry approach, the anteroconid was divided into two separately studied structures: the anterior unpaired loop of the anteroconid (AC) and the base of the anteroconid (AB). The distribution of AC configurations in the space of the two principal components took on an arcuate shape, revealing a “forbidden zone.” The main changes occur on the lingual side of the AC. Regression analysis showed a direct relationship between the length of the contour (mm) and the complication of the shape of the anterior unpaired loop. The base of the anteroconid (AC) also undergoes transformation: it either stretches or contracts, while if the anterior unpaired loop of the anteroconid (AB) is more complex, then simplification and compression of its base is observed (negative regression). Analysis of the results of using two approaches, traditional and GM methods, in the analysis of the variability of the anteroconid section m1 of A. fortis showed extreme subjectivity in the use of the first one and the wide possibilities of the second one for identifying different aspects of molare transformation using mathematical methods.

New material on the planthopper species, Bolbossus bervoetsi Gnezdilov et Bourgoin, 2016 (Issidae, Issinae, Parahiraciini), originally described more than 100 years ago based on an adult of unknown sex from the Baltic amber, is redescribed and illustrated based on a female and fifth instar nymph recently discovered in the collection of the Natural History Museum of Denmark (Copenhagen).

In the Neva River estuary, 188 species and taxa of a higher rank of benthic animals were found, of which 129 were found in the eastern part of the Gulf of Finland. At present, the zoobenthos of the estuary is dominated by eurybiont species inhabiting polluted waters. We used integrated index IP' specially devised for water-bodies and rivers of the north-western Russia to assess the water quality and a state of ecosystems of the Neva estuary. It is based on structural parameters of zoobenthic communities and makes it possible to take into consideration the pollution by toxic and organic substances. On average the water quality of the Neva Bay assessed from IP′ values was relatively stable during 1994–2021. It was assessed as “polluted” with the exception of 2006 and 2015 caused by large-scale dredging works. In the period 1982–2021, the average number of zoobenthos species at one station in the Neva Bay almost doubled, from 12 ± 1 species in 1982 to 23±2 species in 2020. In the resort area of the eastern Gulf of Finland, the values of species richness and the Shannon index were much lower than in the Neva Bay, and on average for one station varied from 5±0.6 to 14±4 species and from 1.1±0.2 to 2.3±0.2 bit/ind. This is caused by the influence of salinity, eutrophication and pollution, and invasion of alien species. In addition to intense anthropogenic impact, the dynamics of the state of zoobenthos in this part of the estuary was determined by climate fluctuations.

There are several external and internal abnormalities that affect development in both wild and farmed fish. One of these abnormalities is known as saddleback syndrome (SBS), characterized by abnormalities in the shape, number, or absence of dorsal pterygiophores, causing a concavity in the dorsal region and absence of fin sections. The causes of this syndrome are not yet clear, but could be caused by fishing or predator damage, nutritional deficiencies, genetic conditions and environmental stress from pollutants that may cause alteration in the ontogenetic development of the fish. This study recorded for the first time the SBS in a wild-caught specimen of Thorichthys meeki Brind, 1918 (Cichlidae). Specimens were collected in the locality of Chekubul, municipality of Carmen, Campeche, México on November 18, 2022. The development of the dorsal fin begins from the first to the ninth dorsal spine where there is a dorsal concavity, which ends with the last three dorsal spines. There is no evidence of scoliosis or lordosis from the X-ray analysis; however, the dorsal pterygiophores show irregularities in their development. The specimen with the syndrome showed no other body abnormalities that would have prevented its development to adulthood, although the causative agent is unclear.

Characteristics of the karyotype and early meiosis of two males of the cryptic “western” form of the viviparous lizard (Zootoca vivipara Lichtenstein, 1823) (genus Zootoca Wagler, 1830) with multiple sex chromosomes (female Z₁Z₂W/Z₁Z₁Z₂Z₂ male) were examined. The data obtained were compared with 1) those of the males of the same cryptic form from other locality, with 2) those of the males of other cryptic form also possessing the multiple sex chromosomes and with 3) those of the species of closely related genus Takydromus Daudin, 1802 with simple sex chromosomes, ZW/ZZ. Multiple sex chromosomes may influence meiosis and play a role in isolation. The males of cryptic western form of Z. vivipara studied revealed the karyotype with 36 acrocentric chromosomes (2n=36A). In early meiosis the spreading of synaptonemal complexes (SC) of the bivalents of these males were obtained and analyzed. Eighteen SC were observed, including SC of the Z₁Z₁ (pair 6) sex chromosomes. Characteristics of SC are compared with the number and the shape of bivalents and chromosomes at the diakinesis and metaphase 11 stages of the meiosis of the males from other population and with those in the other cryptic Russian form of the species. Comparative analysis of two cryptic forms has demonstrated some differences in the morphology of SC Z₁Z₁ sex chromosomes at the early stages of prophase 1 of meiosis (the late zygotena – the middle pachytene stages). However both the SC of sex chromosomes and SC of all remained chromosomes were fully synapted. All 18 bivalents were regular segregated forming haploid spermatocyte II with18 chromosomes, including two sex chromosomes (n=8, Z₁Z₂) Thus characteristics of karyotype and early meiosis of the males of western form belonging to different localities are fully coincident with those of Russian cryptic forms of Z. vivipara with multiple sex chromosomes as well. However, these features were differed from those for the species of the closely related genus Takydromus with simple sex chromosome system (ZW) where some disturbances in the course of mitoses and meiosis were observed. The results are in agreement with those suggested previously about the genomic factor(s) stabilizing the meiosis and the maintenance of multiple sex chromosome in the different cryptic forms of complex Z. vivipara.

Biophysical changes occurring in Arctic marine ecosystems under the influence of climatic factors may affect cetaceans staying here. For this reason, the urgent task is to conduct regular monitoring of marine mammals in order to assess the state of their populations and preserve the biodiversity of species. We analyzed the results of ship-based surveys of marine mammals carried out by the Polar branch of VNIRO in January–March 2019–2023 in the south of the Barents Sea and compared them with the observation data of earlier years. As the studies have shown, the winter cetacean fauna is currently represented by six species of baleen Mysticeti and toothed Odontoceti whales. White-beaked dolphin Lagenorhynchus albirostris Gray, 1846 was the most abundant and widespread species among all cetaceans; however, since 2022 we have seen a decrease in both the number of observations and abundance of this species. Fin whale Balaenoptera physalus Linnaeus, 1758 and killer whale Orcinus orca Linnaeus, 1758 were regularly registered in the study area, while sightings of harbor porpoise Phocoena phocoena Linnaeus, 1758 and humpback whale Megaptera novaeangliae Borowski, 1781 were single. Comparative analysis of the obtained data with the materials of 2012–2013 revealed some changes in the cetacean fauna that occurred during the last decade. In the waters of the southern part of the Barents Sea, there began met species that had not been previously recorded in our surveys, first of all, minke whale Balaenoptera acutorostrata Lacépède, 1804 and humpback whale. The materials we collected expanded our understanding of cetaceans staying in the western sector of the Russian Arctic during the winter.

The results of trapping, measuring the size and weight of the body of the European Nightjar, as well as migration routes according to the data of the ringing in the Kaliningrad region during 1957–2016 are discussed. The annual number of migrating birds has fluctuated significantly for 60 years, and the number of those caught and ringed varied from one to 44 individuals in different years. They were most numerous in May, in the period 1969–1981. Four ring recoveries of Nightjars ringed by us were obtained, which gives the effectiveness of ringing of this species with nocturnal activity of only 0.92%. However, these ringing results indicate that in autumn the migration routes of Nightjar population from the western parts of Scandinavia and from southern Finland run through the eastern coast of the Baltic Sea, and later, on the way to Africa, their azimuth of flight varies from 178° to 203°. The longevity record according to the data from one male of the subspecies Caprimulgus europaeus zarudny E. Hartert, 1912 was 15 years. The migration routes of this species are discussed according to the latest literature data.

This paper focuses on the fine structure of mother sporocysts, the least studied stage of the digenean life cycle. The ultrastructure of the tegument of mature mother sporocysts of Bunocotyle progenetica was examined by transmission electron microscopy and described in detail. The tegument of these parthenitae is represented by an outer anucleate syncytium connected with the deeper-lying tegumental cells by cytoplasmic bridges. Its outer plasma membrane forms minute leaf-like outgrowths and numerous deep invaginations in the shape of interconnected channels. These channels, which pass in various directions and permeate almost the entire outer syncytium, considerably amplify its surface area. The cytoplasm of the outer layer of the tegument contains large mitochondria, microtubules and rare dense secretory granules, whose contents are discharged into the lumen of the channels. Numerous pinocytotic vesicles originate from the plasma membrane of the channels. Small endocytic vesicles are transported along the cytoplasmic bridges to the tegumental cells, where endocytosed food material is sorted and broken down. These cells are characterized by a well-developed Golgi apparatus, which is represented by multiple stacks of cisternae, and the presence of numerous endosomes at different maturation stages and residual bodies. Some steps of endosomal maturation in the tegumental cells were traced. In addition to their digestive activity, tegumental cells produce secretory granules, which are transported to the outer syncytium after their maturation. It was shown for the first time that in mature parthenitae, the population of tegumental cells could be renewed at the expense of a reserve pool of undifferentiated cells. The ultrastructural features of the tegument of mother sporocysts of B. progenetica are discussed in light of the concept of the enhanced trophic function of the tegument in sporocysts lacking the alimentary canal.

The following data was acquired from literary sources and obtained by us as a result of field studies on the distribution, stationality, abundance and reproduction of voles of the genus Blanfordimys Argyropulo, 1933: Afghan vole B. afghanus (Thomas, 1912) with subspecies B. a. afghanus and B. a. balchanensis (Heptner et Shukurov, 1950), Bukhara vole B. bucharensis (Vinogradov, 1930), with subspecies B. b. bucharensis and B. b. davydovi (Golenishchev et Sablina, 1991) and Pamir vole B. juldaschi (Severtzov, 1879) with subspecies B. j. carruthersi (Thomas, 1909) and B. j. juldaschi in natural conditions on the territory of Turkmenistan, Tajikistan and Kyrgyzstan. According to the elevation gradient from low to high altitude, these voles are distributed as follows: Afghan, Bukhara, Pamir, respectively. The features of reproduction and postembryonic ontogenesis in captivity have also been studied. Reproduction took place year-round with low intensity: the number of newborns in the litter of all the species considered is small, 3 cubs on average, the average interval between litters is about 50 days. The young of voles living at lower altitudes (B. afghanus and B. bucharensis) develop somewhat faster compared to higher-altitude ones (B. juldaschi). In general, the studied species showed signs of slow development and delay in the appearance of the most important signs in postembryonic ontogenesis (eruption of incisors, epiphany) compared to most of the lowland representatives of the Arvicolini tribe voles. These features are more pronounced in B. j. juldaschi, living at high altitudes. Thus, considering the theory of pace-of-life syndrome (POLS), we observe a shift from a faster pace of life (r-strategy), characteristic of most lowland rodents, to a slower one (k-strategy). The vulnerability of voles of the genus Blanfordimys in the process of climate aridization and in conditions of anthropogenic pressure is noted.

Preparation techniques are given for making permanent or nonpermanent microscope slides of the mosquitoes and the blackflies (Diptera: Culicidae: Simuliidae). We mention here only those that we have personally found to be most satisfactory in the order to further study the morphology of dipterans. These techniques are required for a detailed examination of the diagnostic characters of mosquitoes and blackflies, as a result, to correctly identify the specimens. First, the general stages of processing specimens are considered, then the specifics for making permanent or nonpermanent microscope slides are given (in glycerin, Canadian balsam and euparal). Preparation techniques of larvae and adults (males and females) of mosquitoes and blackflies, as well as blackfly pupae, are discussed in detail, because these processes differ in each group and in each stage of the life cycle. Moreover, we give the technique for damaged material (i.e., as a result of loss of fixing fluid). For the first time, the description of diagnostic characters that are lost during the preparation is considered in detail. We have specified the structures of blackfly larvae, pupae and adults, whose characters must be described before making permanent microscope slides. We consider that some structures (i.e., the male genitalia of fam. Culicidae and Simuliidae) should be pre-examined on nonpermanent microscope slides, and then permanent slides can be made.