The article provides a detailed illustrated description of a new genus and species of the tribe Halyini (Heteroptera: Pentatomidae: Pentatominae) from Myanmar. The description is based on external morphological characters and the structure of the male and female terminalia, including the completely inflated aedeagus. A detailed comparison of the new genus with the closely related genera Halys Fabricius, 1803 and Neohalys Ahmad et Perveen, 1982 is given, as well as a key for these three genera.

Adropion camtchaticum sp. nov. (Tardigrada: Eutardigrada: Itaquasconidae) is described. The type specimens of the new species were found in a moss sample collected on the Kamchatka Peninsula. The new species is most similar to A. scoticum (Murray, 1905), but clearly differs from the latter in the larger body size, thinner bucco-pharyngeal tube, the presence of teeth in the oral cavity, and toothed bases of claws of all legs. It is the first record of semiterrestrial tardigrades from the continental part of the Russian Far East.

We describe Tenuibiotus yeliseii sp. nov., a new tardigrade species from Svalbard, using morphological and morphometric analyses conducted with the use of light and scanning electron microscopy, as well as genetic analyses based on four molecular markers (three nuclear, 18S rRNA, 28S rRNA, ITS-2, and one mitochondrial, COI). A phylogenetic analysis of the genus Tenuibiotus Pilato et Lisi, 2011 is conducted using new data. In addition, the taxonomic significance of gibbosities on leg IV as a key character for species identification in Tenuibiotus is discussed. A key to the species of Tenuibiotus is proposed.

A new recent foraminiferal genus, Raskiniella gen. nov., with the type species Spirillina plana Wiesner, 1931, belonging to the family Raskiniellidae fam. nov., order Raskiniellida ord. nov. (subclass Spirillinana: superorder Spirillinoida), is described based on samples from Antarctica. The new genus is characterised by a complex canal system that has not been previously described in any other subclasses of multichamber foraminifera with a canal system. Canals extend inside the shell wall and are partly visible as a network on the wide peripheral margin of the shell. On the dorsal surface, these canals are radially arranged, resembling ribs, and extend perpendicularly to the chamber volutions towards the centre but do not reach it. A unique feature of the described canal system is the presence of smaller canals within larger ones; sometimes internal canals can be of third or even fourth order. The majority of the canals are located within the wall of the tubular chamber, forming a network of irregularly branching tubes that frequently intertwine, varying in shapes and sizes, often with swellings. It is the collective mass of these canals that constructs the framework of the shell. The round openings with a slightly projecting outer margin, located on the ventral side of the shall, previously described as pores in S. plana, are actually the external openings of the canal system and function as additional apertures. Since the type species of Spirillina Ehrenberg, 1843, S. vivipara Ehrenberg, 1843, like apparently all other or most species of the genus, does not possess a canal system, S. plana is transferred to the new genus, which is placed in the subclass Spirillinana.

The species composition and diagnostic characters of the Arge ochropus species–group are reviewed. This species group is circumscribed based on the structure of the genitalia. It contains only four species, including A. gussakovskiji sp. nov. described here from the Pamir Mountains in the Gorno-Badakhshan Province of Tajikistan. A key to the Palaearctic species of the A. ochropus group is provided. The differences between the A. ochropus group and the other species groups of the genus Arge Schrank, 1802 with similar coloration are discussed.

Cheilotrichia (Empeda) umiat (Alexander, 1955) (Diptera: Limoniidae), previously known only from the holotype collected in Alaska, has been found on the Putorana Plateau in the north of East Siberia. The species is recorded for the first time from Russia and the Palaearctic region. On the Putorana Plateau, the species was collected in stony river valleys at altitudes of 200–300 m. An illustrated redescription of the male and a description of the female of Ch. (E.) umiat is provided. Cheilotrichia (E.) areolata (Lundström, 1912) has also been collected in the Putorana Plateau and recorded for the first time from Siberia. Its diagnosis and illustrations are provided; the distribution in the Palaearctic and the habitats in the Putorana region are briefly discussed.

Five new species of plume moths (Lepidoptera: Pterophoridae) are described from Ecuador: Platyptilia azuayensis sp. nov., Hellinsia juliae sp. nov., H. razboinikovi sp. nov., H. muratovi sp. nov., and H. elini sp. nov. Two species of Pterophoridae, Quadriptilia obscurodactyla Gielis, 1994 and Stenoptilodes brevipennis (Zeller, 1874), are recorded from Ecuador for the first time.

Trirogma caerulea Westwood, 1841 is recorded from the Fergana Valley in Uzbekistan. This is the first record of this species and the genus Trirogma Westwood, 1841 from Uzbekistan, Middle and Central Asia.

Tephritis ruralis (Loew, 1844) and T. sahandi Mohamadzade, Korneyev et Khaghaninia, 2011 are recorded from Armenia for the first time. The morphological details of five species of Tephritis Latreille, 1804 [T. araileri Evstigneev, 2020, T. conaraileri Evstigneev, 2020, T. ruralis, T. sahandi, and T. truncata (Loew, 1844)] are illustrated in colour photos. It is shown that some Armenian specimens of T. ruralis have two hyaline spots in the pterostigma (as does T. truncata), unlike the European specimens of T. ruralis. The glans of the phallus of T. truncata is illustrated for the first time. Scorzonera rigida Auch. ex DC. is recorded for the first time as a host plant of T. araileri.

New records of two crab spider species, Bassaniodes ovadan (Marusik et Logunov, 1995) and Runcinia tarabayevi Marusik et Logunov, 1990, from Azerbaijan are presented. Both species are recorded from the Caucasus for the first time.

New data on the morphology, distribution and host plants of three species from the Terellia virens group are provided. Terellia freidbergi Korneyev, 2013 and T. ivannikovi Korneyev et Evstigneev, 2013 are redescribed based on fresh specimens having the body shape and colour characteristic of living flies. Terellia zerovae Korneyev, 1985 is recorded for the first time from Russia; T. ivannikovi, previously known from the Samara Province of Russia, is recorded for the first time from Armenia and from the Saratov and Ul’yanovsk provinces of Russia. Centaurea takhtajanii Gabrieljan et Tonjan is recorded for the first time as a host plant of T. ivannikovi. In Armenia, the larvae of T. freidbergi develop in capitula of C. kotschyi persica (Boiss.) Greuter, C. (Chartolepis) sp., C. polypodiifolia Boiss, C. daralagoezica (Fomin) Greuter and C. spectabilis (Fisch. et C.A. Mey) Sch. Bip.; all these taxa are recorded for the first time as host plants of T. freidbergi. A key to identification of seven species of the T. virens group occurring in Armenia and Russia, is provided.

Three nominal species of eelpouts endemic to the Sea of Okhotsk, specifically Lycodes ygreknotatus Schmidt in Taranetz, 1937, L. microlepidotus Schmidt, 1950, and L. fulvus Toyoshima, 1985, are reinvestigated based on all type materials and additional specimens. The latter two species are recognised as junior synonyms of L. ygreknotatus, as no significant morphological differences were found among these taxa. Lycodes ygreknotatus is rediagnosed. It exhibits significant geographic variability in both the number of vertebrae and the density of scale cover. The observed variability can likely be attributed to differences in environmental temperatures across different parts of its extensive distribution range.

This paper presents the results of a study and describes a new species of pelobionts, Pelomyxa pilosa sp. nov. (Archamoebae: Pelobiontida). This species was found in the bottom sediments of a pond near St Petersburg (Russia) and was examined using light, immunofluorescence, and transmission electron microscopy. It is placed in the genus Pelomyxa Greeff, 1874 based on a combination of morphological features, including the mode of locomotion, the presence of numerous flagella, the organisation of the cytoplasm, and the presence of obligate prokaryotic endocytobionts. The new species can be easily distinguished from congeners by the specific presence of numerous prokaryotic ectobionts on the cell surface and the organisation of the nuclear apparatus. The nucleolar material in this species forms a hollow sphere consisting of tightly adjacent patches of various shapes and sizes, surrounded by granular material.

Specimens of the rare benthopelagic deep-water calanoid Pseudeuchaeta acuticornis Markhaseva et Schulz, 2006 (Copepoda: Calanoida: Aetideidae) were collected in the Kurile Kamchatka Trench area in the northern Pacific at abyssal depths. The morphology of these individuals aligns well with the diagnosis of the species. This is the first record of the species from the Pacific Ocean.

A new species of snailfish, Crystallichthys longirostris sp. nov., is described from Kronotskiy Bay, southeastern Kamchatka, from depths of 192 to 200 m. The new species differs from the three other species of the genus, C. mirabilis Jordan et Gilbert, 1898, C. cyclospilus Gilbert et Burke, 1912, and C. cameliae (Nalbant, 1965), in the unusually elongated shape of the narrow snout, the dot-like round pupil, simple (not three-lobed) teeth, and the short distance from the anus to the beginning of the anal fin (9% vs. 17–19% of standard length). The colour is pink, with clearly defined red-brown rings in an elongated oval shape. The new species is also recorded near the Northern Kuril Islands at a depth of 309 m. The diagnosis of the genus Crystallichthys Jordan et Gilbert, 1898 is emended considering the characters of the new species.

The article presents the first records of the genera Epitobrilus Tsalolikhin, 1981 and Eutobrilus Tsalolikhin, 1981 (Triplonchida: Tobrilidae), along with the description of two new species, Epitobrilus brachystomus sp. nov. and Eutobrilus minutus sp. nov., from paddy fields in West Bengal, India. Epitobrilus brachystomus sp. nov. differs from the congeners in having a relatively shorter stoma, distinct crustaformeria cells at the oviduct–uterus junction, five to six setae including a subterminal one in the tail region, and a longer tail with a distinct cuticular protrusion at the tip. Eutobrilus minutus sp. nov. can be distinguished from Eu. husmanni (Altherr, 1958) by the differences in the body size, the distance between the stomatal pockets, the tail length, and the presence of a subterminal setae. From another closely related species, Eu. nothus Gagarin, 1989, it differs in the ratio of the body length to the tail length (c), the tail length relative to its diametre (c′), the distance from the vulva to the anterior body end (V %), and in the distance between the stomatal pockets.

A new species of the genus Miridiba Reitter, 1902, M. yingjiangensis sp. nov., is described from the Yunnan Province, China. The genera Laotrichia Keith, 2007 and Siamophylla Keith, 2005, along with the species L. cuccodoroi Keith, 2007 and S. grootaerti Keith, 2005 are recorded from China for the first time. Six species of the subfamily Melolonthinae are also recorded from China for the first time: Cyphochilus obscurus Sharp, 1876, Lepidiota acuminatops Prokofiev, 2015, Lepidiota cochinchinae Brenske, 1894, Malaisius siamensis Li et Yang, 1999, Malaisius mollis Arrow, 1941, and Pedinotrichia magna (Itoh, 1995). The female of M. mollis is described and illustrated for the first time.

A new species of the genus Subeucalanus Geletin, 1976 (Copepoda: Calanoida: Eucalanidae), Subeucalanus dextrolateralis sp. nov., is described based on female and male specimens collected in the Sea of Oman in October 2019. The new species is placed in the S. pileatus species–group. Subeucalanus dextrolateralis sp. nov. differs from its congeners in the shape of the anterior part of the head and the spermathecae pattern in the female, the structure of the fifth leg in the male, and the right-sided position of the longest caudal seta in both sexes. Morphological characters of the ten known species of the genus Subeucalanus (including the new species) are discussed. A key to the species of this genus is provided.

The invertebrate fauna of the Hissar State Reserve in Uzbekistan remains largely unstudied. In this reserve, we collected and examined darkling beetles, which are among the most diverse and abundant groups of beetles in Middle Asia. All species were found at altitudes ranging from 1,800 to 2,500 meters, spanning the zone of Juniperus seravschanica Kom. and mountain steppes to the border of subalpine meadows. In total, 21 species were collected, one of which, Prosodes (Uroprosodes) chigrayi Nabozhenko et N. Bekchanov sp. nov., is new to science. Another species, Bioramix (Planoplatyscelis) latipennis (Kaszab, 1940), is recorded for the first time in the fauna of Uzbekistan. Additionally, we found and examined the very rare species Laena dentitibia Reitter, 1901, which was previously known only from the male holotype. The female of the rare species Blaps aruktavica G.S. Medvedev, 2004 is characterised for the first time. Two female specimens of the very rare Hissar population of Blaps caraboides Allard, 1882, which have a pronounced elytral mucron, were found for the first time in 112 years. We provide illustrations of the majority of species for the first time. Data on the distribution, taxonomy, external morphology, variability, and bionomics of the examined species are presented.

Until now, Lochmaea crataegi (Forster, 1771) was considered a transpalaearctic species, while the closely related species L. machulkai Roubal, 1926 was known only from the Caucasus and adjacent regions. The present study establishes that L. crataegi is found exclusively in Western, Central, and Southern Europe, while L. machulkai is distributed in Crimea, the central and southern regions of European Russia, the Caucasus, northern Iran, eastern Turkey, and western Middle Asia. A new species, L. sergeevi sp. nov., is described from Asian Russia, specifically from the Urals to the Far East. The males of L. sergeevi sp. nov. differ from those of L. crataegi and L. machulkai in the aedeagus, which is much wider than that of L. crataegi, with the maximum width located closer to the apex than in L. machulkai (in dorsal view), and significantly less curved than in both compared species (in lateral view), and in the metatibia which is curved near the mid-length, whereas it is curved closer to the base in both of the compared species. The diagnostic characters of the L. crataegi species–group, as well as those of L. crataegi and L. machulkai, are revised. Colour photographs of the diagnostic characters and a distribution map of all species are provided.

In 2023, B. Kryštufek and G.I. Shenbrot published a paper in which they proposed to consider invalid 20 lectotype designations based on the specimens in the collection of mammals at the Zoological Institute of the Russian Academy of Sciences (St Petersburg). They also designated a lectotype for Lemmus obensis bungei Vinogradov, 1926. We argue that the authors’ decision was based on an incorrect interpretation of Article 74.7.3 and some other Articles and Recommendations of the International Code of Zoological Nomenclature. The history of Article 74.7.3 is briefly reviewed to highlight its destabilising nature and to draw attention to this within the zootaxonomic community.

Based on material collected by the author over several years and seasons in Chaunskaya Bay of the East Siberian Sea, a new species, Chaetozone buzhinskajae sp. nov., is described. Morphologically, it is most similar to Ch. setosa Malmgren, 1867 and Ch. pugettensis Blake, 2015, which belong to a group of species characterised by an enlarged lobe or crest covering the peristomium. The new species is distinguished by the presence of neuropodial spines in the anterior part of the last third of the body (from the 48th to the 72nd setigerous segment), a complete achaetous segment that is well separated from the peristomium and setiger 1, and a distinctive methylene green staining pattern. Specimens were collected at depths ranging from 12 to 50 m in the seaward part of the bay.

The nudibranch genus Acanthodoris Alder et Hancock, 1845 includes 15 recognised species, most of which are distributed in the temperate marine waters of both hemispheres, but only two species were known from the Russian seas: the widely distributed trans-Arctic A. pilosa (Abildgaard in Müller, 1789) and A. uchidai Baba, 1935, which is found from in the Kuril Islands. The main aim of this study is to revise the species composition of Acanthodoris in Russian waters, evaluate the genetic population structure of the trans-Arctic A. pilosa in the context of connectivity among its distant populations, and infer the phylogenetic relationships between the Russian species of Acanthodoris and other representatives of the family Onchidorididae. The material was collected from eight localities in the subarctic and North-West Pacific waters. The methods employed included morphological analyses, particularly, scanning electron microscopy and computer microtomography, as well as molecular analyses of partial fragments of genetic markers: cytochrome c oxidase subunit I, 16S rRNA, histone H3, 28S rRNA, and 18S rRNA. The genus Acanthodoris is represented in the Russian seas by two species: the North Atlantic and subarctic A. pilosa and the North Pacific A. atrogriseata O’Donoghue, 1927, which is recorded here for the first time from Russia. Acanthodoris uchidai represents a separate clade that is not related to other Acanthodoris; therefore, a new genus Acanthomira gen. nov. is proposed herein, with a single representative species Acanthomira uchidai, comb. nov. We also provide evidence for the existence of cryptic biodiversity within North Atlantic A. pilosa. Our current phylogenetic hypothesis suggests an independent loss of the rachidian teeth in both Acanthodoris and Acanthomira gen. nov., although this should be further tested with a larger taxon sampling. The results of this study emphasise the necessity of incorporating molecular analyses to confirm species identity and to prevent the description of new Nudibranchia taxa based solely on subtle morphological differences.

A new species, Scolopostethus gissarensis sp. nov. (Heteroptera: Rhyparochromidae: Rhyparochrominae: Drymini), is described from Middle Asia (Kazakhstan, Uzbekistan, Tajikistan, and Kyrgyzstan). The new species is placed in the genus Scolopostethus Fieber, 1860, based on a combination of morphological characters. The structural characters of the foreleg and the paramere distinctly differentiate it from other Palaearctic species within this genus. Scolopostethus gissarensis sp. nov. is primarily compared to S. decoratus (Hahn, 1833). Colour photographs depicting the habitus and structural details of the body are provided for both S. gissarensis sp. nov. and S. decoratus (Hahn, 1833).