Phylogeny and morphology of some European cyathocotylid digeneans (Trematoda: Diplostomoidea).

The Cyathocotylidae Mühling, 1898 is a family of primitive diplostomoid trematodes important for understanding the evolution of the superfamily Diplostomoidea. However, cyathocotylids remain poorly studied with the use of molecular techniques. In this study we sequenced the 5.8S + ITS2 region, 28S rRNA, and cox1 genes of two cyathocotylid species and obtained new morphological data on them. We propose Georduboisia nom. nov. instead of the preoccupied name Duboisia Szidat, 1936 (junior homonym of Duboisia Stremme, 1911). Adults of Georduboisia cf. teganuma (Ishii, 1935) and Paracoenogonimus ovatus Katsurada, 1914 were collected from fish-eating birds in the south of the European part of Russia. Georduboisia cf. teganuma was very similar to G.teganuma but differed from it in the shape of the testes. The 28S rRNA gene dataset provided the best-resolved phylogeny of the Cyathocotylidae to date. In the phylogram based on partial sequences of this gene, P. ovatus was close to members of Holostephanoides Dubois, 1983, Neogogatea Chandler & Rausch, 1947 and Gogatea Szidat, 1936. Georduboisia cf. teganuma clustered with members of Cyathocotyle Mühling, 1896 and Holostephanus Szidat, 1936. Phylogenetic analysis based on the 5.8S + ITS2 dataset showed that adults of P. ovatus examined in our study were conspecific with the metacercariae from the musculature of fish collected in Hungary and Italy. It also revealed probable misidentifications of larvae and adults of cyathocotylids whose sequences are deposited in GenBank NCBI.

Pathogens in Ixodes persulcatus and Ixodes ricinus ticks (Acari, Ixodidae) in Karelia (Russia).

Ixodid ticks (Acarina, Ixodidae) are vectors of dangerous human infections. The main tick species that determine the epidemiological situation for tick-borne diseases in northern Europe are Ixodes ricinus and Ixodes persulcatus. In recent years, significant changes in the number and distribution of these species have been observed, accompanied by an expansion of the sympatric range. This work summarizes the data of long-term studies carried out in Karelia since 2007 on the infection of I. persulcatus and I. ricinus ticks with various pathogens, including new viruses with unclear pathogenic potential. As a result, tick-borne encephalitis virus (TBEV, Siberian genotype), Alongshan virus, several representatives of the family Phenuiviridae, Borrelia afzelii, Borrelia garinii, Ehrlichia muris, Candidatus Rickettsia tarasevichiae and Candidatus Lariskella arthropodarum were identified. Data were obtained on the geographical and temporal variability of tick infection rates with these main pathogens. The average infection rates of I. persulcatus with TBEV and Borrelia burgdorferi sensu lato were 4.4% and 23.4% and those of I. ricinus were 1.1% and 11.9%, respectively. We did not find a correlation between the infection rate of ticks with TBEV, B. burgdorferi s.l. and Ehrlichia muris/chaffeensis with the sex of the vector. In general, the peculiarities of the epidemiological situation in Karelia are determined by the wide distribution and high abundance of I. persulcatus ticks and by their relatively high infection rate with TBEV and B. burgdorferi s.l. in most of the territory, including the periphery of the range.

No strict host specificity: Brain metacercariae Diplostomum petromyzifluviatilis Müller (Diesing, 1850) are conspecific with Diplostomum sp. Lineage 4 of Blasco-Costa et al. (2014).

Metacercariae of Diplostomum petromyzifluviatilis (Digenea, Diplostomidae) from the brain of European river lamprey Lampetra fluviatilis from the Baltic Sea basin and Arctic lamprey Lethenteron camtschaticum from the White Sea basin were studied with the use of genetic and morphological methods. Phylogenetic analysis based on cox1 marker showed that the parasites of both lamprey species were conspecific with Diplostomum sp. Lineage 4 of Blasco-Costa et al. (2014). The name Diplostomum petromyzifluviatilis Müller (Diesing, 1850) has historical precedence as a species described from the brain of lampreys and should be used in genus nomenclature. There were no morphological qualitative differences between the metacercariae from the two lamprey species but those from L. fluviatilis were larger than those from L. camtschaticum. We expanded the data on the second intermediate hosts and the localization of D. petromyzifluviatilis, showing that its metacercariae occur not only in the brain of lampreys but also in the brain and the retina of three-spined stickleback Gasterosteus aculeatus and the vitreous humour of the perch Perca fluviatilis across the European part of the Palearctic.

Long-term dynamics of Ixodes persulcatus (Acari: Ixodidae) abundance in the north-west of its range (Karelia, Russia).

The article presents the results of long-term observations of variations in the abundance of Ixodes persulcatus, carried out since 1982, in the middle taiga subzone of Karelia. Adult questing ticks were collected from vegetation following standard flagging procedures. The time series was evaluated by singular spectrum analysis. Correlation coefficients were calculated for the observed tick abundances and meteorological data (mean daily air temperature and precipitation) for the current year and preceding years. Analysis of the time series revealed the trend and harmonic components with periods of 8, 2.5 and 4 years. Around 83% of the total variance is explained by the first principal component, which governs the general vector of change-a gradual reduction in I. persulcatus abundance from 2003 to 2017. Correlations between tick abundance and climatic indices were observed in all years and were associated with both temperature and precipitation. The greatest number of significant coefficients was obtained for correlations between tick abundance and weather conditions in the preceding season. An equation was suggested where tick abundance is described by a linear function with four variables: mean air temperature in April and July, total precipitation in February, and annual number of days with temperatures above 5 °Ð¡. Thus, the observed long-term dynamics are characterized by the following key patterns: a sharp population rise early in the 2000s, some recent decline (stabilization) of the abundance, the presence of quasi-periodic cycles, and a close correlation between tick abundance and climatic variables.

Helminths of brown bears (Ursus arctos) in the Kola Peninsula.

We present data on the species composition of helminths in brown bears (Ursus arctos) from the Murmansk Region, Russia. The absence of any information about helminths of brown bear in the region necessitated the conduct of these studies. Samples were collected in 2014 and 2015 in the southern part of the Kola Peninsula from the White Sea coastal habitats. Annually, in the study area, 1-3 bears are legally hunted and biological samples for examination are very difficult to obtain. Therefore, we used fecal samples. We studied 93 feces and identified parasite eggs identified in 43 of them by morphometric criteria. The surveys revealed eggs of the following helminths: Dicrocoelium sp., Diphyllobothrium sp., Anoplocephalidae, Capillariidae, Baylisascaris sp., Strongylida 1, and Strongylida 2. These results represent the first reconnaissance stage, which allowed characterizing the taxonomic diversity and prevalence of parasites of brown bears of the Kola Peninsula.

[Helminth fauna of the bank vole myodes glareolus (Schreber, 1780) in the Kizhi Archipelago].

The present study was aimed to examine the specific features of the helminth fauna in insular populations of the bank vole (Myodes glareolus) in the north of the species range. The material was collected in and nearby the Kizhi Archipelago (Lake Onega, 62°1' N 35°12' E) during August 1997, 2005-2007, 2012 and 2013. Small mammals were trapped on 23 islands (varying from 2 to 15,000 ha) and on the mainland. Helminthological met- hods were applied to examine 301 specimens of M glareolus. Fourteen helminth species were found: trematodes--Skrjabinoplagiorchis vigisi; cestodes--Paranoplocephala omphalodes, P. gracilis, Catenotaenia henttoneni, Taenia mustelae, Cladotaenia globife- ra, Spirometra erinacei; nematodes--Trichocephalus muris, Aonchotheca murissylvatici, Hepaticola hepatica, Heligmosomum mixtum, Heligmosomoides glareoli, Longistriata minuta, Syphacia petrusewiczi. The parasites S. vigisi, S. erinaci, H. hepatica and T. muris were identified in the bank vole in Karelia for the first time. Significant differences were detected between the helminth faunas of local insular populations of the bank vole. A distinctive feature of all small islands was that samples from them lacked the widespread pa- rasitic nematode Heligmosomum mixtum. The studies have confirmed the general trends observed in the parasite fauna of most isolated populations of small mammals: a poorer species diversity and high infestation rates with certain species of parasites. The Kizhi Archipelago is characterized by the specific high abundance of regionally rare parasite species (H hepatica, A. murissylvatici), and by the absence of common parasites (H. mixtum, H. glareoli).

[IXODID TICKS (PARASITIFORMES: IXODIDAE) FROM SMALL MAMMALS IN DEFORESTED BOREAL HABITATS IN THE NORTHERN EUROPEAN RUSSIA].

Changes in the population density of two hard tick species, Ixodes (Exopalpiger) trianguliceps Birula, 1895 and Ixodes persulcatus Schulze, 1930, were examined in 1998-2001, and in 2003-2004 near Gomselga Village (Kondopoga District, 62° 04' N, 33° 55' E) in central Karelia. Data on the abundance of ixodid ticks and the species composition of their hosts in 4 forest sites at different stages of post-felling regeneration (secondary succession), i. e. 7-14, 12-19, 25-32, and 80-87 after logging were obtained. I. persulcatus dominated, comprising 73 % of the total tick number in samples. Regenera- tion of the forest resulted in fluctuations of the population density of two examined tick species: I. (Exopalpiger) trianguliceps (larvae 2.8-5.3; nymphs 1.5-2.2; adults 0-0.09) and I. persulcatus (larvae 4.3-10.6; nymphs 0.6-4.2).

[Concerning the problem of the northern limit of Ixodes persulcatus (Acari: Ixodidae) distribution in Karelia].

The influence of changes in climate conditions on the abundance and formation of the northern limit of Ixodes persulcatus distribution in Karelia has been studied. It has been demonstrated that the territory in which the heat provision is sufficient for the development of ixodid ticks significantly increased during 2000-2007. Thus, it favored an increase in the abundance and enhanced distribution of I. persulcatus.

[Abundance of larvae and nymphs of the taiga tick Ixodes persuicatus (Acari: Ixodidae) on small mammals in the cut-over lands of the middle taiga subzone of Karelia].

Data of long-term investigations (1998-2004) on the abundance of the taiga tick larvae and nymphs in the cut-over lands of different age in the middle taiga subzone of Karelia (62 degrees 04'S; 33 degrees 55'W) are presented. The investigation was carried out on three model cut-over lands of different age: 1) "young" cut-over land; age of cut-over in the beginning of investigation is 7 years; Betula-Deschampsia cespitosa-Agrostis tenuis; 2) "middle" cut-over land; age of cut-over is 12 years; Salix-Deschampsia cespitosa-Agrostis tenuis; 3) "old" cut-over land; age of cut-over 25 years; Alnus incana-Rubus idaeus-grass. The number of ticks was estimated by using common parasitological indices: prevalence, abundance, and index of feeding intensity (the tick abundance multiply by the number of small mammals per hundred traps-nights). In the beginning of investigation the "young" cut-over land was a typical meadow association. The lowest tick abundance was recorded here. That was a result of unfavorable abiotic conditions and low number of small mammals in the beginning of summer. "Middle" cut-over land is characterized by the highest number of the tick larvae, which is the evidence for high number of the hosts of tick imago. "Old" cut-over land has the optimum conditions for development of taiga ticks. High abundance of the ticks (larvae and nymphs) was recorded during the whole period of investigations. The number of preimaginal ticks is shown to be much higher in cut-over lands as compared with that in mixed and coniferous forests, due to the higher number of small mammals.

[Dynamics of the helminth fauna in the common shrew (Sorex araneus L.) from cut-over lands of different age in Karelia].

Species diversity of helminths in the common shrew from three cut-over lands of different age in Karelia was studied. It was shown, that change of the plant cover in cut-over lands have no a significant effect on the species diversity of helminth communities in Sorex araneus, but the abundance of individual parasite species changes considerably. Changes of the S. araneus infestation with helminths were the greatest in a new cut-over land. Structure of the helminth community comprises four categories of parasites (dominants--4 species, subdominants--8, rare species--13, very rare species--10) and depends on the time passed since the felling. A redistribution of the species constituting the core of the helminth fauna was to be observed. It was shown, that being an integrated indicator of the status of terrestrial ecosystems, parasites clearly indicate changes not in the structure, but in the abundance and domination of individual species of terrestrial invertebrates and vertebrates in cut-over lands.

[Biotope distribution of cestodes from the common shrew Sorex araneus in southern Karelia]. / Osobennosti biotopicheskogo raspredeleniia tsestod obyknovennoi burozubki (Sorex araneus L.) Iuzhnoi Karelii.

Specific features in the formation of cestode species composition in the common shrew in different biotopes have been analyzed. Four categories of parasites have been recognized depending on a degree of dominance: dominants (Neoskrjabinolepis singularis, Molluscotaenia crassiscolex), subdominants (Ditestolepis diaphana), adominants A (Staphylocystis furcata, Vigisolepis spinulosa, adominants B (Hymenolepis scutigera, Dilepis undula, D. secunda, Taenia mustelae). A significant similarity was discovered between the species diversity and the dominance characteristics of cestodes. It was found that the distribution of mass species of parasites in the host population corresponds to the gamma distribution model. In regard to cestodes examined, a hypothesis considering the spatial structure and size of territory occupied by stable parasitic system is put forward.