Parazitologiâ

In the digenean superfamily Hemiuroidea, a number of species are registered from a wide geographic range including the Arctic, Atlantic and Pacific Oceans. However, these distributions have not yet been confirmed with the molecular methods. In the present study, we performed molecular analysis of Progonus muelleri (Levinsen, 1881) (Derogenidae) from distant regions: the European sub-Arctic (the White, Barents and Pechora Seas) and the Pacific Northwest (the Sea of Okhotsk and the Pacific coast of the northern Kuril Islands). Two genetic lineages within P. muelleri, PM1 and PM2, are proved to occur in sympatry in the European sub-Arctic. We found minor differences in their maritae structure, and thus suppose they represent two pseudocryptic species. PM1 was also registered in the Pacific Northwest (PM1b) where it has differences in cox1 gene from the European sub-Arctic lineage (PM1a). The intramolluscan life-cycle stages of P. muelleri from the Sea of Okhotsk are described and compared with the ones from the White Sea. We hypothesize that PM1a, PM1b and PM2 are three distinct species, but this should be further tested.

During 2018–2024, the invasion of Succinea putris in St. Petersburg and the Leningrad Region was studied. The main attention was paid to the infection of snails with sporocysts of Leucochloridium. Three species of this genus were found: L. paradoxum, L. perturbatum and L. vogtianum. However, during the autopsy of Succinea putris, seven more species of parasites were noted, belonging to both trematodes and other groups of multicellular and even protists: ciliates of the Intramacronucleata subtype, coccidia Klossia sp., metacercariae of the trematodes Brachylaima mesostoma and Pseudoleucochloridium soricis, metacestodes Monocercus sp., nematodes of the Mermithidae family, dipteran larvae Pherbellia sp. In addition, various combinations of multiple infections formed by these parasites have been noted.

In the Sothern Trans-Urals region (Kurgan region) 125 individuals of ticks were collected on the western periphery of the Dermacentor silvarum range during April–August 2020–2024 on the small mammals using the methods of the trapping grooves and trap lines. D. silvarum is found throughout the entire territory of Kurgan Oblast. During the long-term period (1980s and 2020–2024) its parasitization was noted on 19 species of small mammals and one hybrid form (russet and red-cheeked ground squirrel). D. silvarum was found more often than other small mammals on the common shrew, northern red-backed vole, narrow-headed vole, field vole and tundra vole. The occurrence and abundance of this tick are very low. D. silvarum belongs to moistened and afforested territories in the herb-bunchgrass steppe, but in forest-steppe and subtaira does not avoid open spaces.