Cestode diversity in shrews from islands in the Sea of Japan and the Sea of Okhotsk.

A comparative analysis of taxonomic diversity on shrew cestodes among four islands in the Sea of Japan and the Sea of Okhotsk (Sakhalin, Kunashir, Hokkaido, and Moneron) was performed. Cestode species shared among the islands were identified and their host specificity was investigated. On Sakhalin Island, 33 species of the families Hymenolepididae, Dilepididae and Mesocestoididae were recorded in four shrew species (Sorex caecutiens, S. gracillimus, S. minutissimus and S. unguiculatus). In S. caecutiens, S. gracillimus, and S. unguiculatus on Kunashir Island, 22 species of the same families were found and, on Hokkaido Island, 23 species of the families Hymenolepididae and Dilepididae were recorded. On Moneron Island, three species of cestodes were registered in S. tundrensis. The Sakhalin-Hokkaido-Kunashir complex of shrew cestodes includes eastern-Palearctic, trans-Palearctic and endemic species. High endemism (~22%) of shrew tapeworms in the Sakhalin-Kunashir-Hokkaido Islands was noted as compared to continental territories. The different numbers of cestode species in S. unguiculatus (31), S. caecutiens (29), S. gracillimus (19) and S. minutissimus (1) were found. It was concluded that the cestodes species diversity of shrews of Sakhalin-Kunashir-Hokkaido depended primarily on the history of island formation, their modern physical and geographical features, the abundance of definitive and intermediate cestodes hosts and, to a lesser extent, on the size and remoteness of the islands from the mainland and the diversity of host species.

Neoskrjabinolepis paradoxa n. sp. from shrews on Sakhalin Island, Russia, with an amended diagnosis of Neoskrjabinolepis Spassky, 1947 (Cestoda: Cyclophyllidea: Hymenolepididae), a key, and a review on geographical distribution of the species.

A taxonomic review was performed on cestodes of the genus Neoskrjabinolepis Spassky, 1947 that parasitize different species of Sorex shrews in different regions of the northern Palearctic and in the Nearctic (Alaska, USA). Information on Palearctic Neoskrjabinolepis cestodes published in various articles is summarized. An overview of the geographical distribution of the Neoskrjabinolepis species is also presented. Currently, the genus includes 17 species. In the European part of the Palearctic, four species of the genus are registered; in the Asian part, 13 species; and on the American continent (Seward Peninsula, Alaska, USA), two species. Descriptions, illustrations, and differential diagnoses are given for a new species of Neoskrjabinolepis, i.e. N. paradoxa n. sp., which was found in shrews Sorex unguiculatus Dobson and S. caecutiens Laxmann on Sakhalin Island. A unique feature of the new species is irregularly alternating genital pores in the uterus series in the strobila. Amended new differential features (positioning of the uterus relative to osmoregulatory canals and alternation of genital pores) of genus diagnosis and an identification key for Neoskrjabinolepis spp. are presented.

First Data on the Contact Zone and Hybridization between the Cryptic Species of Shrews Sorex araneus and S. satunini (Eulipotyphla, Mammalia).

For the first time, based on sequence variation of microsatellite loci and the mtDNA cytb gene fragment, population genetic structure of the common shrew and Caucasian shrew in their contact zone was investigated. It was demonstrated that, although there was no complete reproductive isolation between the species under consideration, the gene flow was considerably limited. These data testify to the established reliable reproductive barriers between the common shrew and Caucasian shrew.

[Interaction of the uterus and developing eggs in cyclophyllidean cestodes with different fecundity].

The interaction of morphological changes of the uterus and fecundity of the strobilus of cestodes has been investigated. It is shown that cestodes with maximal fecundity have different and highly effective ways of supplying eggs with nutrients. It is noted that differences in fecundity of cestodes depend not only on their strategy of reproduction, ecology, and complexity of life cycles but also on the complexity of interactions between the uterus and the developing eggs.

[Soricinia sawadai sp. n. (Cyclophyllidea: Hymenolepididae), a new cestode species from the shrews of Sakhalin Island].

A new species Soricinia sawadai sp. n. parasitizing shrews of Sakhalin Island (Sores unguiculatus and S. caecutiens) is described. The new species differs from other species of the genus Soricinia Spassky et Spasskaja, 1954 in having specific armament and size of the cirrus. Soricinia sawadai sp. n. differs from S. aurita (Irzhavsky et al., 2005) in having half size of the ovary (0.076-0.08 x 0.03-0.038 versus 0.135-0.14 x 0.037-0.04) and the cirrus bursa extending into the aporal fraction of the middle part of segment. The new species differs from S. quarta (Karpenko, 1983) in having half size of the cirrus (0.025-0.026 versus 0.05-0.055) and half number of hexacants in uterine segments (20-22 versus 40-45). The new species differs from S. infirma (Zarnowski, 1955) in having other cirrus armament, larger number of segments and lesser number of hexacants. The species Insectivorolepis macracetobulosa Sawada et Koyasu, 1991 parasitizing Sorex unguiculatus on Hokkaido Island is synonymized with Soricinia quarta. The species Insectivorolepis macracetobulosa sensu Sawada et Harada, 1993 parasitizing Sorex shinto shinto on Honshu Island is described as a separate species Soricinia haradai sp. n.

[Morphogenesis of the Staphylocystis furcata cysticercoid (Cyclophyllidea, Hymenolepididae)].

The morphogenesis of the Staphylocystis furcata (Stieda, 1862) cysticercoids has been studied in the experimentally infected beetles Geotrupes stercorosus and their structural and ontogenetic features have been described. At the initial stage of its development metacestode of S. furcata forms lacuna primitiva. The primordium of scolex invaginates early into the posterior part of the larva, and then the scolex develops in the cyst cavity. There is only an anterior obturator valve developing in the cyst. Posterior obturator valve is absent, that results in the cyst remaining unlocked and the cercomer does not separate from the cyst. There is no lacuna primitiva in the cercomer. The tegument of metacestode gets covered with a solid fibrous layer at the final stage of morphogenesis. It makes the cyst partly or completely pressed in the anterior part of the cercomer when it grows. The similarity between S. furcata cysticercoids and morphologically related cysticercoids Hymenolepididae has been analysed.

[Brachylepis gulyaevi nov. sp. (Cestoda: Cyclophyllidea: Hymenolepididae)--a new species of cestodes from shrews of the North-Eastern Altai].

The description and differential diagnosis of a new species Brachylepis gulyaevi nov. sp. (the genus Brachylepis Karpenko, Gulyaev, 1999) from Sorex shrews of the North-Eastern Altai is given. Brachylepis gulyaevi nov. sp. differs from other species of the genus in the number of proglottids in strobila, length and armament of cirrus, presence of glandular cells covering cirrus pouch, external seminal vesicule and vagina. The mature uterine segments are very long and comparable with the length of strobila.