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.

On the example of cestodes, it was shown that in the Pliocene, transberingian exchanges of shrews and associated parasites took place on a larger scale than in subsequent periods. This is confirmed by 10 common genera of cestodes in shrews of the Palearctic and Nearctic. In the Pleistocene, cestodes of only three genera, Lineolepis, Neoskrjabi nolepis, and Spasskylepis, entered Alaska from Asia.

The first data on the cestode fauna of shrews in the North Caucasus, in particular, its western and central parts, are presented. In total 27 cestode species from 17 genera and two families (Hymenolepididae and Dilepididae) have been revealed. Most of the fauna is composed of taxa with transpalaearctic distributions, these amounting to 55.6% of the species diversity. European and Caucasian (endemic) elements account for 18.5 and 25.9% of all species, respectively. The cestodes Pseudobothriolepis mathevossianae and Coronocanthus sp. are recorded from the Caucasus for the first time. The genera Coronocanthus, Monocercus, Neoskrjabinolepis, Spasskylepis, and Soricinia contain species morphologically different from the known congeners, all probably new and thus likely to increase the number of species endemic to the region. The tapeworms species diversity of the mesophilous host species ( Sorex and Neomys ) is higher compared to xerophilous ones ( Crocidura ), amounting to 23 and four species, respectively. The infestation rate of the North Caucasian shrews by different cestode species is analyzed.

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.

The aim of this study was to assess the taxonomic diversity and prevalence of shrew cestodes on the Kamchatka Peninsula and Paramushir Island on the basis of current understanding of cestode taxonomy. The diversity of shrew cestodes included 22 species from three families: Hymenolepididae, Dilepididae, and Mesocestoididae. In Paramushir, the diversity of shrew cestodes was substantially lower than in Kamchatka (14 and 22, respectively). In Kamchatka, three genera of cestodes (Novobrachylepis, Mathevolepis, Ditestolepis) were not found, but three species from genera Lineolepis, Staphylocystis, and Monocercus are possibly new species. The potential for endemic species and the unique characteristics of the cestode fauna on Kamchatka suggest that the peninsula may have been a refugium for shrews and their parasites in the last glacial maximum. In Kamchatka and Paramushir, two Nearctic species (Lineolepis parva and L. pribilofensis) were found, which indicates potential dispersal from North America. Most cestode species in Kamchatka were associated with the host shrew Sorex caecutiens, while in Paramushir most cestodes were associated with Sorex isodon. In Paramushir, shrews had higher prevalence of infection with cestodes than in Kamchatka. The dominant cestode taxa in shrews on Paramushir Island were species rare in Kamchatka. Conversely, the most abundant cestode species in shrews on Kamchatka were absent from the island fauna.

Neoskrjabinolepis (Neoskrjabinolepis) yanchevi n. sp. is described from common shrews Sorex araneus L. (Eulipotyphla: Soricidae) from Pirin Mts., Bulgaria (type-locality) and Russia (Arkhangelskaya Oblast’). The new species is characterised by ten rostellar hooks 37–40 μm long and possessing claw-like blades with crooked middle parts and well-developed epiphyseal thickenings of handles; a whip-shaped cirrus, 80–100 μm long, consisting of basal region with numerous small, rosethorn-shaped spines, and middle and distal regions armed with fine, needle-shaped spines; vagina provided with sphincter close to its orifice, with copulatory and conductive part not clearly distinct from one another; 40–50 eggs per gravid uterus. The species is differentiated from the remaining 4 species of the nominotypical subgenus of the genus Neoskrjabinolepis, which are parasites of the Palaearctic shrews of the genus Sorex.

Un total de 12 cestodos adultos se colectaron de los conductos biliares de ratones domésticos (Mus musculus) provenientes de Lima, Perú. Diversas características del escólex y proglotis maduros del cestodo fueron observadas para la identificación morfológica. Así mismo, se realizó un diagnóstico molecular mediante un PCR y secuenciación parcial del gen mitocondrial citocromo c oxidasa subunidad 1 (cox1). Todos los cestodos fueron identificados como Hymenolepis microstoma por morfología y métodos moleculares. El aislado de H. microstoma de Perú mostró una similitud de secuencia significativa (> 99%) con los aislados de H. microstoma previamente reportados. Nuestro informe confirma la presencia del parásito en ratones de Lima.

The variability of the microsatellite loci of the Caucasian shrewSorex satuniniin the North Caucasus was evaluated. It was shown that this species on this territory is represented by two discrete genetic lines associated with the basins of the Kuban and Terek rivers. The genetic diversity of the Caucasian shrew from the line of the Kuban River basin is characterized by a significantly higher polymorphism compared to the line from the Terek River basin. These differences are associated with both modern habitat conditions ofS. satuniniand the history of this species in the Western and Central Caucasus.

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.

We analyse the phylogenetic relationships and taxonomic status of hymenolepidid cestodes with rudimentary rostellum, parasitic in Holarctic shrews of the genus Sorex. These cestodes were previously termed as a 'Ditestolepis clade' and encompass eight genera: Diorchilepis, Ditestolepis, Ecrinolepis, Gulyaevilepis, Mathevolepis, Novobrachylepis, Spalania and Spasskylepis. Representatives of seven of these were available for molecular study, including type species of all seven genera. Phylogenetic analysis based on partial sequences of the 28S rRNA gene supports this group of genera as monophyletic. The 'Ditestolepis clade' consists of two subclades. One of these includes genera containing cestodes having suckers positioned inside bothrium-like depressions (Ditestolepis, Gulyaevilepis and Spasskylepis). The second subclade contains cestodes with suckers expanding far beyond the margins of the scolex (Mathevolepis, Ecrinolepis, Spalania and Novobrachylepis). The relative taxonomic value of several additional morphological characters is discussed. Genetic data convincingly demonstrate that Ditestolepis diaphana, Spasskylepis ovaluteri and Mathevolepis macyi represent complexes of morphologically similar species. Based on the phylogenetic analysis, we resurrect the genus Spalania. Amended generic diagnoses and keys to identification of the genera in the Ditestolepis clade, as well as keys to the known species, are provided.

An inventory of tapeworms in shrews from various natural zones of Yakutia was carried out. Cestodes of 33 species, 16 genera and three families have been found: Hymenolepididae, Dilepididae and Paruterinidae. The highest species diversity, 29 species, is recorded in central Yakutia, vs. by one-third lower (20 species) to the east. In the South of Yakutia, 13 species are registered. While moving to the tundra zone, a double depletion of the cestode fauna of shrews is observed. Peculiarities of the distribution of cestodes with serial strobilation (Ditestolepis, Ecrinolepis, Mathevolepis and Spasskylepis) have been studied over the territory of Yakutia. These cestodes form the core of the tapeworm community of Palearctic shrews. The genus Neoskrjabinolepis is the most representative in including seven species. Contrary to the existing faunistic reports, the presence of the species Neoskrjabinolepis schaldybini, Staphylocystoides borealis and Vigisolepis sp. has not been confirmed in the territory of Yakutia. The majority of cestodes of shrews in Yakutia belong to Eastern Palaearctic species. Trans-Palearctic species account for less than a third of their list, and only one species (Neoskdabinolepis fertills) has a Holarctic distribution.

Жанетта Вячеславовна Корнева - доктор биологических наук, активный исследователь тонкого строения и тканевой организации паразитических плоских червей, скончалась 12 сентября 2017 г. на 55-м году жизни. Вся трудовая деятельность Жанетты Вячеславовны связана с Институтом биологии внутренних вод им. И. Д. Папанина Российской академии наук (ИБВВ РАН, пос. Борок, Ярославская обл.).

ФГБУН Институт аридных зон Южного научного центра РАН, г.Ростов-на-Дону

The ultrastructure of the reticular uterus has been analyzed in pregravid and gravid proglottids of cyclophillid cestodes dwelling in water (Alcataenia dominicana and A. larina) and in terrestrial hosts (Arostrilepis tenuicirrosa). Cells of the medullary parenchyma surrounding the uterus are filled with lipid inclusions in all species investigated. The hypertrophic development of small excretory ducts that surround the uterus, contact the uterine epithelium, and penetrate the diverticula is characteristic of Alcataenia dominicana and Arostrilepis tenuicirrosa. A comparative analysis of the results and the data available for other cestode species allow for the assumption that the reticulate structure of the uterus, lipid accumulation, and contacts between the uterine epithelium and the excretory ducts are morphological and functional adaptations that enable matrotrophy and the attainment of maximal fecundity by cyclophillid cestodes.

Some cyclophyllidean cestodes provide protection for their eggs in the external environment by providing them with additional protective layers around the egg membranes. In attempting to examine such adaptations, the microanatomy and fine structure of the uterus of pregravid and gravid proglottids of the cyclophyllidean cestode Orthoskrjabinia junlanae, a parasite of mammals that inhabit a terrestrial but moist environment, were studied. In the initial stages of uterine development, developing embryos locate freely in the lumen of a saccate uterus that later partitions into chambers. Each chamber that forms encloses several embryos. The chambers are surrounded by muscle cells that synthesize extracellular matrix actively. The paruterine organs consist of stacks of flattened long outgrowths of muscular cells, interspersed with small lipid droplets. In the gravid proglottids, the size of paruterine organ increases and consists of flattened basal and small rounded apical parts separated by constrictions. The fine structure of the organ wall remains the same: sparse nuclei and stacks of flattened cytoplasmic outgrowths but internal invaginations or lumen in the paruterine organ are absent. Completely developed eggs remain localized in the uterus. Based on the comparative morpho-functional analysis of uterine and paruterine organs and uterine capsules in cestodes, we conclude that these non-functioning paruterine organ in O. junlanae is an example of an atavism. We postulate that the life cycle of the parasite, which infects mammals living in wet habitats, where threats of desiccation of parasite ova is reduced, has favoured a reversion to a more ancestral form of uterine development.