Vol 103, No 8 (2024)

Based both on original and literary data, the results of long-term studies on the helminth fauna of alcids (the Little Auk, Alle alle, the Razorbill, Alca torda, the Atlantic Puffin, Fratercula arctica, the Black Guillemot, Cepphus grylle, the Common Guillemot, Uria aalge, and Brünnich’s Guillemot, U. lomvia, in the Barents Sea region are summarized. 31 species of helminthes (4 trematodes, 11 cestodes, 12 nematodes and 4 acanthocephalans) have been revealed. Some of them circulate in coastal ecosystems, but the realization of life cycles in most species occurs in the pelagial zone with the participation of planktonic invertebrates and fish as intermediate and transport hosts. 24 helminth species of 31 do not reach sexual maturity in alcids and use either other birds or marine mammals as obligate definitive hosts. The structure of the parasitic fauna and the peculiarities of geographic and interspecific distribution of helminthes are related to the evolutionary age of parasite-host systems, host ecology and parasite specificity. A comparative analysis of the helminth faunal composition of alcids in the North Atlantic and Barents Sea shows that Barents Sea birds have a lower diversity of trematodes and cestodes. Differences in the nematode faunal composition are insignificant, whereas records of acanthocephalans are more frequent in the Barents Sea. This seems to be accounted for by different species of parasites having different requirements for environmental conditions and varying degrees of specificity to both intermediate and definitive hosts.

A new species of Liocranidae is described and illustrated from Uzbekistan: Mesiotelus uzbekistanicus sp. n. (female). An identification key is given to Mesiotelus species from Middle Asia and Iran.

A revision of the complex vernalis-robustus group of Acanthocyclops, characterized by 17-segmented antennules and elongated caudal branches, from Palaearctic water bodies is carried out. In total, about 10 taxa of this group have been described from this region, including the invasive American species Acanthocyclops americanus (Marsh, 1892). After this revision, six taxa are recognized as valid, including another species, A. borutzkyi Chaban et Alekseev sp. n. from Sakhalin Island, described here as new. Acanthocyclops magistridussarti Stoch et Bruno, 2011, from groundwaters in Italy, is synonymized with A. orientalis Borutzky, 1966, which also inhabits caves in Primorye of Russia and in South Korea. Acanthocyclops trajani Mirabdullayev et Defaye, 2002 and A. einslei Mirabdullayev et Defaye, 2004, both described from France and Germany, are downgraded to junior synonyms of A. americanus and A. robustus (G. O. Sars, 1863), respectively. Descriptions of all six valid taxa are provided and an identification key is given to all species of this group from Palaearctic water bodies.

Pancreas Aselli, large mesenteric gland, central fatty inclusion, fatty or large lymphoid body are some of the names for the large mesenteric lymph node characteristic of shrews. Despite the attention this organ has attracted due to its large size comparable to that of a kidney, it has long remained a mystery to theriologists. Due to the seasonal and age-related variability in weight and size revealed, it has been allotted exclusively metabolic or even storage functions. An analysis of the studies on the large mesenteric lymph node has made it possible to trace the changing views on the roles this organ play in the lymphatic and immune systems of shrews, and to assess the prospects for its further study.

The movements of three mature beluga whales (Delphinapterus leucas) tagged by satellite transmitters off the western coast of Kamchatka Peninsula were analyzed. Before the formation of ice cover, beluga whales remained off the western coast of Kamchatka and in the Shelikhov Bay. As ice was formed and spread, beluga whales used increasingly deeper water areas. The data obtained indicate the possible residence of belugas in the eastern part of the Sea of Okhotsk and prove the genetic isolation of this beluga population from that of the western Sea of Okhotsk.