Vol 45, No 7 (2018)

Phoronida is a phylum of marine invertebrates with a worldwide distribution. Currently, there are 14 species of phoronids in the world fauna, but this number may increase, based on the latest research. In the present study, the morphology and microanatomy of a new phoronid species, Phoronis savinkini sp. n., from the Gulf of Tonkin in the South China Sea are studied. The new phoronid species forms highly dense populations on rocky ground covered with soft sediment at a depth of 2 m. Since the epidermal collar at the base of the tentacles is absent, we refer this species to the genus Phoronis. The lophophore is a one-coil spiral in shape. There are 154 (160) tentacles. Special reproductive glands in the lophophoral cavity are absent. Longitudinal muscle bundles are of the bushy type. The maximum number of bundles is 50. Each metanephridium has a strongly curved excretory canal and two funnels: anal (small) and oral (large). There are two giant nerves of 2–5 μm in diameter. A comparative analysis of the morphological characters used in phoronid taxonomy shows that the morphology of the new phoronid species from the South China Sea seems to be the most similar to that of Phoronis hippocrepia Wright 1856, which has two morphs, one burrowing in hard ground and the other living in soft substrates. However, there are significant morphological differences between the two species: a fundamentally different type of lophophore organization, which is the main taxonomic character in phoronids, a different type of organization of excretory organs (including the structure of the nephridial funnels), and the absence of reproductive glands in the crown of tentacles in the new species. The cladistics analysis of phoronid taxonomic diversity shows that the ecological division of phoronids into two groups (burrowing and living in soft substrates) is meaningful taxonomically as well. Burrowing and digging phoronids might have diverged long ago. The muscle type and the number of branches of the nephridial canal can be considered as the main differences between the two groups. In the present paper, the monophyly of the genus Phoronopsis and the paraphyly of the genus Phoronis are shown. Secondary simplification of Phoronis ovalis is assumed. A separate clade that includes Phoronis pallida and Phoronis embryolabi is suggested.

We studied the innervation of unpaired branchial appendages using confocal laser scanning microscopy in two annelid species: Terebellides cf. stroemii (Trichobranchidae) and Cossura pygodactylata (Cossuridae). The branchial filament was found to be innervated by one unpaired segmental nerve coming from the ventral nerve cord at the level of chaetiger 2 in C. pygodactylata. This nerve lies transversally along the body wall and comes laterally to the base of the branchial filament. Such a structure indicates that (1) the branchial filament is unpaired and neither represents merged paired branchiae nor is related in its origin to prostomial appendages or peristomial ones, and (2) the branchial filament is the result of a shift of one of the paired segmental branchiae with parallel reduction of the second branchia in this pair. The branchial organ of T. cf. stroemii is innervated by paired segmental nerves from the first and second chaetigers. The segmental nerves are connected by longitudinal nerves going on the lateral sides of the body closer to the dorsum. One nerve on each side proceeds to the anterior part of the branchial stalk, and another nerve proceeds to the posterior part. All these nerves have transversal connections. The anterior stalk nerves come into the anterior branchial lobes, while the posterior nerves come to the posterior lobes. In the branchial lobes, the nerves give rise to thinner nerves, which go to each of the branchial lamellae. The present study confirms that the branchial organ of Terebellides has a paired nature and originates from segmental branchiae. Based on the number of innervating segmental nerves, we can conclude that the branchial organ of T. cf. stroemii is formed by two pairs of merged branchiae.

The distribution of soil invertebrates from different taxa and the adaptive potential of all three cold hardiness strategies in the cold climate of northeastern Asia are analyzed. The correlation between the resistance to low temperatures and the overwintering conditions in habitats of some species is studied. The mechanisms and degree of cold hardiness are shown generally to be unrelated to the taxonomic proximity. The effect of the resistance to low wintering temperatures on the habitat distribution and faunogenesis of soil invertebrates in permafrost regions is discussed.

The formation of the first populations of the marsh frog (the Pelophylax ridibundus complex) near Petropavlovsk-Kamchatsky and in the Paratunka River valley must have been the result of human introduction in the late 1980s. At present, more than 20 localities of this species are recorded in Kamchatka. For a more precise definition of the taxonomic status of P. ridibundus sensu lato, samples from five populations (altogether, 30 individuals) from southeastern and central Kamchatka are analyzed using molecular methods. In all frogs, a mitochondrial DNA type specific for the “eastern” form (=the Anatolian P. cf. bedriagae), but not for the “western” form (=the Central European P. ridibundus), is revealed. However, the results of nuclear DNA analysis of marsh frogs from Kamchatka reveal alleles specific for both of the forms, “eastern” and “western,” with a frequency ratio of about 2 : 1. The results of sequencing the mitochondrial ND2 gene and nuclear SAI-1 gene suggest that the “ancestor” individuals might have been introduced into Kamchatka from the Volga–Don interfluve or Ciscaucasia. The absence of both haplotype and nucleotide diversity in the samples studied suggests a single successful introduction that involved a low number of frogs stemming from a single locality.

Captures of Common Crossbills on the southeastern shore of Lake Ladoga and in the St. Petersburg suburbs (1482 individuals from 1968 to 2015) show that the postjuvenile moult is preceded by migration and the overwhelming majority of migrating young birds have plumage that consists solely of juvenile feathers. The postjuvenile moult is recorded from the end of the first ten days of August to the middle of November, the timing of the onset of moult varies within one and a half months with different individuals being observed to have significant distinctions in the number of replaced feathers. The experiments with photoperiodic regulation of the postjuvenile moult were made on 48 individuals captured in nature in the second half of summer and six young birds from one pair of Crossbills, which bred in captivity. The experimental groups were kept in the conditions of a natural decrease in the day (60° N), decrease in the daylength after the transfer from a long day to a short daylength, increasing daylength, constant long daylength, and constant short daylength. The results of the experiments show that the species-specific features of moult in the Common Crossbill are its start being regulated in a wide age range (from 50 to 180 days) and a rather narrow photoperiodic interval of moult with short daylengths (14.5–9 h of daylight). As long as there is more than 14.5 h of daylight, moult begins under the influence of the endogenous rhythm, but not earlier than the age of 4–6 months. The individuals that moult within the photoperiodic interval replace plumage at high rates. After the daylength gets below the lower threshold of the photoperiodic interval, an inhibiting role of the photoperiodic response is activated, terminating moult in the birds that started moult too late, and their plumage mainly retains juvenile generation feathers. Due to the regulation of moult, intrapopulation differences in the timing of annual cycles that are more than seven months at the time of birth of young Common Crossbills decrease almost five times by its start and become even smaller as it ends. It is assumed that this not only makes it possible to implement moult under optimal conditions but also makes first-year birds ready to start breeding in a timely manner if they find themselves in an area with abundantly fruiting spruce trees.

The known records of the pygmy white-toothed shrew (Suncus etruscus) in the regions of the Kabardino-Sunzhenskii mountain ridge in North Ossetia and the Terskii mountain ridge in Ingushetia are reviewed. The species identity of these animals is confirmed through dental system and morphometric analyses. The history of studies of this species in the Caucasus region is recovered. As a result of these studies, the faunal list of the Russian Federation is enriched with the pygmy white-toothed shrew.

Data on the reproductive success and reproductive behavior of the domestic cat, the most widespread representative of the family Felidae, are presented. The effects of the number of partners, mating order, and sperm quality on male and female reproductive success were assessed. The experiments showed that the fertility of female cats that mated with two partners was higher. Here, male reproductive success was less dependent on the attitude of females to the males, whereas the sperm quality (percentage of morphologically intact spermatozoa) and order of mating with the female had considerable effects on reproductive success. However, male sperm quality did not have a significant effect on the number of offspring if the mating pattern was monogamous.

In order to identify uniform criteria for the classification of arvicoline species as paleoenvironmnental proxies in studies of the environmental dynamics in the Late Pleistocene and Holocene, published data on the distribution and environmental preferences of modern Arvicolinae species inhabiting the central part of northern Eurasia have been compiled. For each of the 17 Arvicolinae species, the following characteristics were examined: (1) thermal neutral zone parameters and temperature preferences of adult individuals; (2) biotopical associations (i.e., the range of abiotic and biotic features of habitats used for breeding, feeding, expansion, and survival in unfavorable conditions), and (3) trophic preferences. It is shown for each of the study species that their most sustainable and conservative environmental preferences within their modern ranges relate to the requirements on the soil and vegetation properties of their breeding and/or survival habitats, as well as trophic specialization. Taking the factors limiting the modern distribution and abundance of the study species, a classification of the arvicolines inhabiting the central part of northern Eurasia based on their environmental preferences has been proposed. The classification specifies the parameters that can be reconstructed based on the species composition of arvicolines, as paleoenvironmental proxies, in micromammalian subfossil assemblages dating back to the Late Pleistocene and Holocene. It also contributes to a better understanding of the position of this taxonomic group within the entire complex of paleoecological proxies. This approach to the identification of environmental groups, based on the trophic specialization and characteristics of breeding and/or survival habitats, is universal for all representatives of the subfamily and may be used as a classification template for Arvicolinae species in any region of the Northern Hemisphere.