Gamasid mites (Parasitiformes, Mesostigmata) of the European arctic and their distribution patterns

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 Hala?kova, 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).