Vol 102, No 1 (2023)

Patterns of changes in the species richness, abundance, community structure, and biomass of testate amoebae were studied in a series of different-type aquatic and terrestrial habitats along an interlake transect in the Tyumen Region. Altogether, 112 species and forms of testate amoebae, including subspecies, were identified. Micrographs of all species detected are given. The species Conicocassis pontiguasiformis (Beyens et al., 1986) Nasser and Anderson, 2015, previously described as an arctic endemic, was found in the south of Western Siberia for the first time. The species richness of testate amoeba assemblages is maximal in the periphyton. The highest values of species numbers and biomass were detected in the bottom detritus of the coastal part of a swamp lake. Testate amoeba assemblages in various habitats along the transect are divided into aquatic and terrestrial, according to the results of cluster and principal component analyses. The species composition of testate amoeba assemblages depended on substrate wetness, as well as the type of vegetation. The dominants in relative biomass were identified for aquatic, forest, and well-lit Sphagnum habitats.

In surveying material of the genus Eulohmannia Berlese 1910, representatives of two new species were discovered. Eulohmannia aborigensis sp. n., described based on all instars, is known only from alpine environments of the Kolyma Highlands in Magadan Oblast, Russia. It is the largest species of the genus known (length often well over 800 µm) and appears to be bisexual. Adults are unique among the known species of Eulohmannia in having a relatively long femur IV (about 2 times the length of trochanter IV), three setae on trochanter III, 14 setae on tarsus IV, and a minute tooth or spine at the base of each lateral claw. Eulohmannia juvenalis sp. n., described based on adults and a single tritonymph, is known only from forest soil in the Kashmir Valley (Kashmir). Among the known species of the genus, adults are unique in having paedomorphic legs, resulting from several specific neotenic characters. The most conspicuous is a monodactylous pretarsus on all legs and the retention of a single seta on trochanters III and IV, but several other setae are delayed or fail to be developed.

Migratory connections in waterfowl in the north of Western Siberia are discussed as based on ring recoveries from the database of the Bird Ringing Center of Russia, A.N. Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences. Altogether, 3531 recoveries from waterfowl of 29 species were used. The waterfowl in the region are characterized by exceptionally wide migratory connections, occurring in different seasons in most regions of the Old World within the Northern Hemisphere: from Iceland to the Japanese Islands and from West Africa to the Indian Subcontinent and the Yangtze River basin. The long-distance flights of birds to molting sites, the interannual change of nesting grounds and wintering regions, as well as the distribution on wintering grounds are discussed. Ten wintering regions have been allocated. The available material on the migration of waterfowl is evaluated from the viewpoint of completing the description of their seasonal distribution and its significance in the study of ecological connections of the territory of Western Siberia.

When assessing the abundance of small mammals using traditional methods, an abundance index, the number of individuals per unit of trapping effort, is usually applied. Due to the different relationships of species to various traps and baits, the true ratio of species in nature may not coincide with the estimated one. In most cases, the presence of a non-resident component in the population size remains outside the attention of researchers, while dispersal is a key element for many demographic processes. A method is proposed for calculating the density (individuals per area) of resident and non-resident animals when using mark-recapture live-traps arranged in lines. For three mass species of small forest mammals (red-backed voles, common shrew and masked shrew), the dynamics of the density of the resident and non-resident population were studied over 18 years. In most cases, the red-backed vole dominated the population of small mammals. According to long-term average data, the proportion of non-resident individuals in the population of the three species did not differ, averaging 12.6% of the total density. The dependence of the level of non-resident activity in the red-backed vole on the density of resident animals was shown. In shrews, the density of non-residents did not depend on the density of resident ones. The technique allows for a wide range of ecological problems to be solved and it can be used to monitor the state and structure of communities of small mammals.

A juvenile specimen of the scallop, Aequipecten opercularis, was found in 2007 in the eastern part of the Varanger-Fjord, Kola coast of the Barents Sea. The northern range limit of this species has earlier been drawn much more southerly, at the Atlantic coast of Norway. This record is the first in Russia’s waters, probably being related to climate warming in the southern part of the Barents Sea since the early 2000’s.