Analysis has been completed of all the available material on gamasid mites from insular and continental territories of the Barents Sea region. A total of 116 species has been revealed, including 9 new to science. The species Gamasus armatus L. Koch, 1879 is transferred to the genus Gamasodes Oudemans, 1939, thus becoming Gamasodes armatus (L. Koch, 1879), comb. n. Six species of gamasid mites occur even at the thermal limit in the Northern Hemisphere, on the ice-free grounds of Franz Josef Land (with mid-July temperatures ranging from −1.2°C to +1.6°C). On Svalbard, 25 species have been recorded, as compared to 27 on Novaya Zemlya, 39 on Vaigach Island, 43 on Kolguev Island, 50 in the Pechora Bay, 37 on Kanin Peninsula, and 58 on the Eastern Murman coast. Despite the differences in the quality and quantity of material obtained during 30 years from numerous collectors, a relation between species diversity and summer heat supply has been revealed (linear regression coefficient: 0.816; significance level: 99%). The most diverse families are Ascidae (23 species, including 20 species of Arctoseius), Parasitidae (15, including 6 species of Vulgarogamasus), and Zerconidae (14, including 11 species of Zercon). The species Zercon michaeli Halaškova, 1977, Zercon solenites Haarløv, 1942, Parasitellus papei (Karg, 1985), Parasitellus arcticus (Karg, 1985), and Halolaelaps gerlachi Hirschmann, 1966 have been recorded in Russia for the first time. The species Zercon acanticus Blaszak, 1978, Poecilochirus nordi Davydova, 1971, Euryparasitus tori Davydova, 1970, Gamasellus tundriensis Davydova, 1982, Arctoseius nikolskyi Makarova et Petrova, 1992, and Neoseiulus ellesmerei (Chant et Hansell, 1971) are new to the European list. The specific gamasid mites associated with lemmings or bumble-bees are absent on Franz Josef Land and Svalbard, since both archipelagoes were almost completely glaciated in the Late Pleistocene. An obviously temporary population of a member of the family Macrochelidae, namely, of the dung-compost cosmopolitan species Macrocheles muscaedomesticae (Scopoli, 1772) was first recorded in the High Arctic (Spitsbergen). Distribution ranges of many species, mainly of those of the genus Arctoseius, lie within the Metaarctic (sensu Yurtsev, 1977). High Arctic patterns have been confirmed for Arctoseius tschernovi Makarova, 2000, A. babenkoi Makarova, 2000, A. productus Makarova, 2000, Neoseiulus sp. aff. tibielingmiut (Chant et Hansell, 1971). However, quite a few of the species traditionally considered as “arctic” and inhabiting mainly arctic landscapes in North America and the western Palaearctic, have also been found in the Siberian mountains as far southwards as the Altai-Sayan mountain system: Antennoseius oudemansi (Thor, 1930), Proctolaelaps parvanalis (Thor, 1930), Zerconopsis labradorensis Evans et Hyatt, 1960, Zercon michaeli, Zercon solenites, etc. Similar arcto-montane patterns have also been revealed for some “mountain” species: Trachytes hirschmanni Hutu, 1973, Syskenozercon kosiri Athias-Henriot, 1976, Veigaia belovae Davydova, 1979, Iphidinychus gaieri (Schweizer, 1961), and Zercon spp. As the climate becomes milder, the total share of arctic and arcto-montane species in the individual regions of the European Arctic gradually drops from 100% (Franz Josef Land) to 12% (Eastern Murman coast).

Cushion plants in alpine ecosystems act as nurse species, which modify and alleviate environmental conditions and positively influence the diversity and abundance of other organisms. Soil f...

A new amphiboreal gamasid mite genus, Thalassogamasus gen. n. is described, characterised by two distinct dorsal shields (opisthonotum hypotrichous, usually with ten pairs of setae); peritrematal shield reduced and posteriorly free; setae al1, al2 on palp genu and al on palp femur entire; dorsal chaetome homogenous; opisthosoma laterocaudally hypertrichous; in female, epigynium whip-like anteriorly, endogynium with two thick sclerotic masss; in male, tritosternum fully lost, hypostome deeply cleft, cheliceral arthrodial membrane fringelike. The new genus includes T. sidortschukae sp. nov. (Chukotka and Okhotsk coast), T. kurilensis sp. nov. (Kuril Islands) and T. lindrothi (Sellnick, 1974) (Iceland) comb. nov. The female of T. lindrothi (Sellnick, 1974) is considered conspecific with the male of Parasitus (Neogamasus) anderssoni Sellnick, 1974, comb. nov., syn. nov. All three Thalassogamasus species are seaside dwellers, inhabiting sandy beaches, salt marshes, and seaweed accumulations. Keys to the species (females and males) are presented. Peculiar morphological aspects of the dorsal shields, peritremes, and leg tarsi of the new genus are discussed. For another littoral species of Parasitidae, Parasitus kempersi Oudemans, 1902, a new combination is established, Phorytocarpais kempersi (Oudemans, 1902) comb. nov. Three littoral species of Uropoda (Phaulodinychus) Berlese, 1903 are first recorded from Russia: U. (P.) japanorepleta Hiramatsu, 1980 (northern and eastern Chukotka, Magadan Region, Kuril Islands), U. (P.) maritima Hiramatsu, 1977, and U. (P.) marihirschmanni Hiramatsu, 1977 (Kuril Islands).

In the Caucasus, the total area taken up by glaciers is known to have reduced by 23% over the last 20 years. This natural experiment allows for additive and replacement models of autogenic succession of biocoenoses within paraglacial landscapes to be tested. A certain risk of the extinction of cryophilic species also exists. However, montane paraglacial successions of invertebrate assemblages have hitherto been studied neither in the Caucasus nor in Russia as a whole. Structural changes of taxocoenoses were traced in a spatial and temporal sequence of ten properly dated paraglacial sites in the Tsey Gorge, North Ossetia − Alania (1–170-years old) among the testate amoebae, earthworms, molluscs, myriapods, mites, spiders, harvestmen, pseudoscorpions, collembolans, and beetles. As the glacier retreats, in place of bare paraglacial wastelands, grassland communities are formed that, after 10–14 years, are replaced by shrub vegetation and, on 30–35-year old surfaces, by forest communities. Most of the invertebrate groups, once “appearing” along a postglacial transect, were recorded from most older plots as well. Yet, their taxocoenoses underwent considerable transformations through increasing (or an increase turning into some decline in beetles) the species diversity and a strong, often complete change in the taxonomic composition and dominance structure. The most considerable transformations were observed at all major vegetation changes. The “appearance” of some groups in the transect was determined not only by dispersion capacities but mainly by the environmental conditions of particular habitats. When comparing the composition of the pioneer postglacial species complex of the study region with that in the mountains of Europe’s south and north, its high-degree regional specificity was noted, sometimes shown at the family level (in spiders). Spatial β-diversity of all larger taxa studied was mainly attributed to turnover (due to “the replacement model” of succession). The general level of change diminished towards the later succession stages. Endemic arthropod species were revealed both in pioneer grassland and developed forest communities.