Vol 46, No 8 (2019)

In summer and autumn 2016–2017, the parasitic fauna in four anemonefish species (Amphiprionclarckii (53 ind.), A. polymnus (58 ind.),A. perideraion (15 ind.), and A. frenatus (10 ind.) (Pomacentridae)) from the areas close to Nha Trang, South China Sea, Vietnam, were studied. In total 11 parasite species were found in the studied fish with 3–8 parasite species per fish species. The survey revealed two species of copepods (Hatschekia sp. 1 and Hatschekia sp. 2), six digeneans (Macvicaria sp. 1, Macvicaria sp. 2, Aponurus piriformis,Aponurus laguncula, Hysterolecitha nahaensis, Bivesicula sp. metacercariae), two nematodes (Spirocamallanus istiblenni and Hysterothylacium sp. J4), and one acanthocephalan (Echinorhynchus sp.). The trematode Hysterolecitha nahaensis and the nematode Spirocamallanus istiblenni were the most abundant and prevalent parasites. These parasites reached a prevalence of 64% and 90% with an intensity of infection of 1–6 ind. and 1–37 ind., respectively. Two ectoparasite taxa were found: Hatschekia sp. 1 (a single specimen found in A.clarckii) and Hatschekia sp. 2. Among them, Hatschekia sp. 2 was the most frequent and abundant species in A. polymnus (prevalence 96.6%, intensity of infection 0–51).

Data available on the peculiarities of the tegument structure and encapsulation of the acanthocephalans Corynosoma strumosum (Palaeacanthocephala, Polymorphidae) and Sphaerirostris picae (Palaeacanthocephala, Centrorhynchidae) in paratenic hosts are summarized. Corynosomes are shown to have a capsule structure varying from fibroblastic to leukocytal depending on the species of the paratenic host (sea fish). The characteristic thick glycocalix layer may or may not develop on the tegument surface of corynosomes surrounded by the leukocytal capsule in the hosts of different species. The acanthocephalan S. picae in a paratenic host (lizard) is also surrounded by a leukocytal capsule; however, no characteristic glycocalyx layer is formed on its tegument surface. Such a glycocalyx supposedly represents a protective reaction of the parasite to cellular encapsulation, but in the case of its absence the protective mechanism remains unclear. Based on these results, a hypothesis about two strategies of interrelations between acanthocephalans and paratenic hosts is advanced. According to the first strategy, the acanthocephalan (C. strumosum in the fish of the majority of the species studied), regardless of the structure of the capsule formed around it, is covered with a thick layer of glycocalyx, while the cells of the inner part of the capsule are destroyed. When invading paratenic hosts of other species (C. strumosum in flatfishes, as well as in experimentally infested aquarium fish and lizards, S. picae in lizards), the second strategy is realized: the acanthocephalan is surrounded by a leukocytal capsule; however, a thick layer of glycocalyx on its surface is not formed and the capsule’s cells are not destroyed.

Illustrated descriptions of two new nematode species found in artificial reservoirs for shrimp cultivation are given: Pseudolella tenuis sp. n. and Paracomesomaleptum sp. n. The former is morphologically close to P. bengalensis (Timm 1957) and P. capera Tchesunov 1978, but differs from P. bengalensis by a shorter body, comparatively longer pharynx, shorter and less slender tail, longer stoma, shorter ventral branch of the amphideal fovea, and shorter spicules and cephalic setae. It differs from P. capera by shorter cephalic setae, wider labial region, longer ventral branch of the amphideal fovea, and longer spicules. Paracomesomaleptum sp. n. is morphologically close to P. susannae Semprucci 2015 and P. minor Gagarin et Nguyen Dinh Tu 2014. From the former species it differs by its shorter and thicker body, shorter cephalic and subcephalic setae, and less numerous precloacal supplements in the male. This new species differs from P. minor by a less slender tail, shorter cephalic and outer labial setae, the presence of subcephalic setae, and longer spicules.

The purpose of this study is to analyze the taxonomic composition of the branchiopod crustaceans (Crustacea: Branchiopoda) from the assemblage of animal and plant remains recovered from fossil mammoth hair found in the Allaikha River basin, Sakha Republic, Russian Federation. We studied the hair structure. AMS radiocarbon dating of both the hair itself and the remains demonstrated their different ages. We found different animal and plant remains in the hair taphocoenosis. The most diverse and numerous remains belong to branchiopod crustaceans: resting eggs and distal portions of the mandibles of Anostraca, distal portions of the mandibles of Notostraca, filtering limbs of some Anostraca or Daphniidae, ephippia of Daphnia (Daphnia) curvirostris, Daphnia (Ctenodaphnia) atkinsoni, and D. (C.) magna. No representatives of D. (Ctenodaphnia) now occur in northeastern Eurasia, but our findings of numerous ephippia in the fossil hair of two mammoths, one from the Allaikha River and the other, studied previously, from the Bol’shaya Chukochya River basin (see Kirillova et al., 2016), show that Daphnia (Ctenodaphnia) taxa occurred in the region at least in the past and were probably common and widely distributed there. The reasons for the extinction of Daphnia (Ctenodaphnia) in northeastern Eurasia require additional special study. We also emphasize the need for further studies of the morphology of ephippia, resting eggs, and mandibles of recent Branchiopoda, which would be essential for adequate identification of Pleistocene remains.

This paper presents the results of a total census of inhabited Dalmatian Pelican nests, which was carried out in spring 2017 using a drone aircraft for the waterbodies of the Kurgan and Tyumen regions. The dynamics of the species numbers in the area studied over the last 50–70 years and the factors affecting these dynamics are analyzed.

Vocal plasticity under changes in social environment is well-known for passerine birds that possess vocal learning, but it has remained almost unstudied for other species. In this paper we studied the effect of social environment (the presence of conspecifics, a pair-mate, and a vocal duel), breeding period, and individuality on the acoustic variables and occurrence of self-advertising calls (trumpet calls) in male crested auklets (Aethia cristatella). This species is a planktivorous seabird that breeds in dense colonies and displays complex social behavior on the colony surface. We collected data in 2008–2010 and 2015 on Talan Island (Sea of Okhotsk); in total we used 1047 calls from 25 individually marked and 62 unmarked males. We found that the majority of males most often emit self-advertising calls when a pair-mate is absent, but other conspecifics are present; most rarely they emit self-advertising calls when a pair-mate is present, but other conspecifics are absent. However, there are some individual differences in those preferences. We suggest that, in the presence of a pair-mate, auklets prefer to use duet displays to signal their social status and pair-mate “occupation.” We also found that the effect of the social environment and breeding period on all acoustic variables measured is weaker than the effect of individuality. However, some of the trumpet call variables (mainly the duration of some syllables inside the trumpet call) changed significantly under the influence of the social environment and breeding period. Thus, crested auklets can slightly change the acoustic variables of their calls depending on the social environment, but keep the overall signature of their calls stable to make vocal individual recognition possible during the entire breeding season.

We have developed a spatially explicit individual-based model that imitates the population dynamics of the Arctic fox on Mednyi Island. In the Red Data Book of the Russian Federation, the Mednyi Arctic fox is listed as an endangered species. The model developed is based on data collected over 19 years of fieldwork. Annual marking of cubs in the study area allowed us to identify up to 80% of animals individually and to collect their life-history data. As a result, we identified the mortality rates of males and females of all age groups, the probabilities of breeding, litter sizes, the sex ratios of animals in different age groups, social structures, dispersion distances, and the patterns of making decisions in the selection of social partners and habitat patches. The model is spatially explicit, i.e., the heterogeneity of the habitat patches is defined in explicit form. The model works with a time step of one year. In simulations, demographic parameters such as population dynamics, population age structure, sex ratio in different age groups, and the structure and size of families conformed to the empirical data. An analysis of the model sensitivity to variations in mortality rates in different age groups showed that the sensitivity to shifts in cub mortality is much higher compared to adults of all age groups. Through increasing the cub mortality rate to 95% over a period of one to five years, we simulated the effect of the otodectic mange epizootic, which was observed in a real population of the Mednyi Arctic fox. The population recovery time after the end of the impact in the simulation was significantly longer compared to field data. We suggest that, in reality, with a low population size, the productivity of the population increases. This feedback that accelerates population recovery has not yet been introduced into the model. In conclusion, we discuss advantages of the individual-based modeling based on long-term field studies.

The serum prevalence of brown (Ursus arctos) and Asiatic black bears (Ursus thibethanus) to 14 different pathogens is analyzed; seropositive bears to ten different pathogens are found. The serum prevalence is at the maximum for Candida sp., pseudorabies virus and Dirofilaria sp. Species-specific differences in the serum prevalence to different pathogens are observed for Trichinella sp. and Toxoplasma gondii, but seropositive individuals are observed only among brown bears. These variations can be explained by differences in the feeding behavior of the brown and Asiatic black bears and the frequency of contacts with the Amur tiger and its kills.

Craniometric features (measurements, indexes) in several species of the genus Sylvaemus (S. sylvaticus, S. flavicollis, and S. uralensis from Eastern Europe and some adjacent territories, as well as S. ponticus and S. witherbyi from the Caucasus) have been studied using multivariate statistical analysis. For the first time, craniometric characters of the genus Sylvaemus are considered in relation to the feeding ecology of species. A total of 614 skulls were studied. Based on original material, discriminant keys have been developed using skull measurements. The keys appear to be suitable for the diagnostics of the studied Sylvaemus species, including sibling ones. The largest skulls are shown to be characteristic of S.flavicollis, and the smallest ones, of S. uralensis. Cluster analysis of the absolute measurements of the skull cumulative selection has revealed the greatest isolation of S. flavicollis and the similarity of coexisting but phylogenetically remote S. ponticus and S. witherbyi. Factor analysis showed that, within the genus Sylvaemus, the general sizes are less essential than the characters related to food smashing (the length of the lower jaw and rostrum, the width of the occipital part of the skull), and possibly also to the thickness of the incisors. Comparative analyses of the relative skull measurements (the indexes related to the food preferences of the animals, granivory or folivory) allow us to conclude that the food adaptations to granivory in the structure of the skull and teeth increase in the series S. uralensis–S. sylvaticus–S. witherbyi–S. flavicollis–S. ponticus. The cranial evolution in species within the genus Sylvaemus is suggested to have been directed to increased adaptations in the mechanisms in seed peeling and processing.