Contents of Proceedings of the Zoological Institute

A new species of liparid fish from the genus Osteodiscus Stein, 1978 is described. The genus is primarily distinguished from Careproctus Krøyer, 1862 in the reduction of soft tissues of the pelvic disk. Three specimens of Osteodiscus lindbergi sp. nov. were caught during the international expedition SokhoBio (“Sea of Okhotsk Biodiversity Studies”, 2015) in the Kuril Basin of the Sea of Okhotsk at an abyssal depth of 3306–3348 m. The new species differs from four other congeners in the number of vertebrae (53) and rays in the dorsal (51) and anal (42) fins, a notched pectoral fin with a moderately elongated lower lobe (that is 67–76% of the length of upper pectoral-lobe), a horizontal mouth, and lack of prickles on the skin. Color of head and body brown, peritoneum black. This abyssobenthal species is presumably endemic to the deep-sea Kuril Basin.

A new material on the genera Steirodon Serville, 1831, Cnemidophyllum Rehn, 1917, Emsleyfolium Cadena-Castaсeda et al., 2016 and Stilpnochlora Stål, 1873 from the subtribe Steirodontina (Steirodontini) as well as on the genera Separatula Gorochov, 2018 and Anaulacomera Stål, 1873, belonging to the subtribe Anaulacomerina (Phaneropterini), is considered. Some subgenera of these genera and their diagnostic characters are briefly discussed. The following new taxa (13) are described: Steirodon (Steirodon) superbum sp. nov. from Peru; S. (Peucestes) para sp. nov. from Brazil; S. (P.) dentatum woronovi subsp. nov. from Colombia; S. (Posidippus) minor sp. nov. from French Guiana; S. (Frontinus) planifemur sp. nov. from Peru; Cnemidophyllum (Peucestophyllum) granti peruanum subsp. nov. from Peru; C. (Peucestoides) bituberculatum sp. nov. from Peru; Emsleyfolium unilobatum sp. nov. from Peru; E. cusco sp. nov. from Peru; Stilpnochlora jalisco sp. nov. from Mexico; S. marginella latistriata subsp. nov. from Surinam; Separatula symmetrica sp. nov. from Peru; S. falcata tenuis subsp. nov. from Peru. Steirodon validum Stål, 1874 and S. (Posidippum) parastahli Piza, 1979 are returned in the subgenera Steirodon and Posidippus Brunner-Wattenwyl, 1878, respectively (but the latter species as a possible synonym of S. stahli Brunner-Wattenwyl, 1878); the generic names Phyllolophus Rehn, 1944 and Steirodonopis Scudder, 1875 are returned in synonyms of the subgenera Steirodon and Frontinus Stål, 1873, also respectively. For the homonymic name Posidippus validus Saussure et Pictet, 1898, the new name S. (Posidippus) major nom. nov. is established, and S. (P.) dentiferoides Emsley, 1970, syn. nov. is synonymized with S. (P.) stahli. For Steirodon (Frontinus) irregulariterdentatum (Brunner-Wattenwyl, 1891), the neotype is designated, and this species is redescribed; Posidippus rarospinulosus Brunner-Wattenwyl, 1891 is transferred to Steirodon (Frontinus), and P. tricenarius Piza, 1974 is treated as a separate species in the same subgenus but not as a synonym of S. (F.) rufolineatum Emsley, 1970. Cnemidophyllum (Cnemidophyllum) tani Cadena-Castaсeda, 2016 is transferred to the subgenus Peucestophyllum Emsley, 1970 of the same genus. For A. (Munticercora) sclerogenitalis woronovi Gorochov, 2021, the male cerci are firstly described.

Valdayskiy National Park is one of the largest protected natural areas in the European part of Russia. On the territory of this national park there are about 200 lakes, one of which is Lake Valdayskoe. The study of its zooplankton community started more than 100 years ago and was repeatedly carried out. The presence of a long series studies provides a rare opportunity to trace changes in the zooplankton community of this unique reservoir. Pelagic zooplankton (Rotifera, Cladocera and Copepoda) of this lake was studied in summers of 1999 and 2020. 39 invertebrate taxa were revealed. The majority of the zooplankton community was typical for the temperate zone of European Russia. The water quality in the lake during the study period can be estimated as oligosaprobic (clean). In areas of the lake located near settlements, an increase in the abundance and biomass of zooplankton, a decrease in the number of indicator species of oligosaprobic waters, and an increase in the proportion of copepods with morphopathology were observed. In general, in 1999 and 2020 zooplankton abundance has declined and biomass has increased compared to the 1970s.

Hysterosphaerius sexpunctatus Melichar, 1906, the type species of the monotypical genus Hysterosphaerius Melichar, 1906, is redescribed based on new materials from Singapore along with male genitalia structures described and illustrated for the first time. Relationships of the genus Hysterosphaerius within the tribe Hemisphaeriini Melichar (Issinae) are discussed.

This paper continues a series of articles concerning the molecular genetic analysis of widespread helminths – cestodes of the genus Mesocestoides Vaillant, 1863, parasitising (at the metacestode stage) small mammals. In this study, we examine the genetic diversity of Mesocestoides spp. from micromammals of the Russian Far East using the cytb gene as an example. Polymorphism of the nucleotide sequence of the cytochrome b gene and the amino acid sequence of the encoded polypeptide was detected for the first time in Mesocestoides spp. parasitising hosts of different genera and species inhabiting this region. Two species of Mesocestoides spp. were identified that were not related to the genetically confirmed species of the genus. One of them was found only in Micromys minutus (Pallas, 1771), obtained near Georgievka village in Khabarovsk Territory. The second species is represented by nine individuals from geographically distant locations, in which two genetic sublines and 11 nucleotide differences in the cytb gene sequence were found. Molecular diversity indices show a high level of polymorphism in the nucleotide sequence of this gene in the gene pool of the studied species of Mesocestoides. In addition, the presence of three isoforms of the cytochrome b polypeptide was established. Analysis of amino acid substitutions in these polypeptide isoforms and the polypeptide from the M. minutus sample also indicates that the latter belongs to a separate species.

In the above-referenced article, Figure 2 was erroneously omitted from the final published version, although all in-text references to this figure were retained in the text. The omitted figure and its complete caption are provided below. The Editorial Board of the journal sincerely apologizes to the authors and readers for this publication error.