The nudibranch genus Dendronotus Alder et Hancock, 1845 is a common component of boreal and arctic ecosystems, which has recently received a considerable attention due to its high cryptic diversity. Here we describe a new species Dendronotus shpataki sp. nov. from the northwestern Sea of Japan, using the material and observations provided by Andrey Shpatak, a local citizen, diver and underwater photographer. We studied morphological features of the new species, including external morphology, coloration, jaw and radular morphology, and configuration of the reproductive system, as well as its ecological traits including possible diet preferences. We obtained DNA sequences and reconstructed the phylogeny by Bayesian Inference and Maximum Likelihood approaches using four molecular markers (mitochondrial COI and 16S rRNA, and nuclear histone H3 and 28S rRNA), and tested the boundaries between the species by calculating the uncorrected p-distances and automatic species delimitation methods ABGD and GMYC. Our results show that D. shpataki sp. nov. differs both morphologically and genetically from all other Dendronotus species. The new species possibly represents a unique example of local endemism, being found in a single locality, while other local Dendronotus species demonstrate wide distribution in the North-West Pacific. We also report on a considerable wearing of the radular teeth during feeding, which is a remarkable case for the Dendronotus.

Four species of the family Crambidae (superfamily Pyraloidea) are reported for the first time from India, based on the material collected from the Andaman and Nicobar Islands in 2018–2020, namely Glyphodes cosmarcha Meyrick, 1887, Palpita cirralis (Swinhoe, 1897), Pachynoa xanthochyta (Turner, 1933) and Pagyda arbiter (Butler, 1879). The diagnoses and the distributional data on these species are provided; the male and female genital structures are illustrated. The female of G. cosmarcha and the male and female genitalia of P. cirralis are described for the first time.

Chrysotus hubenovi sp. nov. is described from the West Rhodope Mountains, Bulgaria. In addition, the records of 37 dolichopodid species are given for seven mountains or mountain massifs in Bulgaria. Sixteen species are recorded as new to the Pirin Mountains, four are new to the Lozenska Mountain, four are new to the Milevska Mountain, two are new to the Konyavska Planina Mountain, five are new to the Vitosha Mountain, five are new to the West Rhodope Mountains, and one species is new to the Belasitsa Mountain. The distribution of 210 dolichopodid species by the altitudinal zones and vegetation belts of Bulgaria is reviewed and briefly discussed.

Two closely related, difficult to diagnose calanoid copepod species, Eudiaptomus transylvanicus (Daday, 1891) and E. vulgaris (Schmeil, 1898), were studied based on the new material from the Sura River floodplain (the Middle Volga region, European Russia). The redescriptions and illustrations of two species are provided. The main diagnostic differences between these species are refined. New characters useful in the identification of E. transylvanicus are proposed. The data on distribution and habitats of the two species are reviewed and briefly analysed.

A new species, Paranthrenopsis sichuanensis sp. nov. from the province of Sichuan, China, is described and figured. A preliminary catalogue of species of the genus Paranthrenopsis Le Cerf, 1911 is provided. The catalogue contains updated taxonomic information including the references to the original descriptions, information on name-bearing types, nearly complete bibliography, and the data on the known distribution of species.

A new species of the genus Ferdinandea Rondani, 1844 and the unknown female of Eumerus muratovi Barkalov, 2020 are described. The new species F. volkovae sp. nov. differs from all Palaearctic species of the genus in the coloration of the face, the frons and mesonotum completely covered with grey pollen, black scape and pedicel, and the details of the male genitalia. The female of E. muratovi is similar to that of E. kozlovi Stackelberg, 1952, but differs in the completely black legs, larger size and presence of brown spot on the wing.

The hitherto unknown queen of the ant species Strumigenys datryx Bolton, 2000 is described. Five species of the ant genus Strumigenys F. Smith, 1860 are newly recorded from Sumatra and illustrated: S. dohertyi Emery, 1897, S. edaragona Bolton, 2000, S. panopla Bolton, 2000, S. rotogenys Bolton, 2000, and S. sydorata Bolton, 2000. A list of 36 species of Strumigenys recorded from Sumatra is provided.

A new subgenus Panjal subgen. nov. of the genus Crossocerus Lepeletier de Saint Fargeau et Brullé, 1835 (Hymenoptera: Crabronidae: Crabroninae: Crabronini) is described from Pakistan, with C. dutti sp. nov. as a type species. The characters for distinguishing the new species from other species of Crossocerus known on the Indian Subcontinent are provided. An updated checklist of the genus Crossocerus of the Indian Subcontinent is given.

A taxonomic review of the genus Ateleute Förster, 1869 in North America is provided. A new species, Ateleute multicolor sp. nov., is described from the State of Veracruz, Mexico. Within the subfamily Ateleutinae, unusual colour pattern of the new species is similar to that of only three species of Tamaulipeca Kasparyan, 2001 occurring in Amazonia. Ateleute carolina maculator Kasparyan et Hernández, 2001 is redescribed. The diagnoses and colour photographs of all Mexican species of Ateleute and a key to the species of Ateleute occurring in Mexico are provided.

Ctenolepisma (Ctenolepisma) turkestanicum sp. nov. is described from southern Kazakhstan. It is the first species of the genus Ctenolepisma Escherich, 1905 with 2 + 2 bristle combs on urotergite II, whereas all described species of Ctenolepisma have 3 + 3 bristle combs on this urotergite. The new species is most close to C. przewalskyi Kaplin, 1982 described from Kyrgyzstan. In addition to chaetotaxy of urotergite II, the new species differs from C. przewalskyi in the distribution of hypodermal pigment and the number of bristle combs on the thoracic sternites.

New data on the distribution and host plants of nine species of Tephritidae are presented. Tephritis oedipus Hendel, 1927, T. hendeliana Hering, 1944 and Terellia uncinata White, 1989 are recorded for the first time from Transcaucasia. Urophora sirunaseva (Hering, 1938) is recorded for the first time from Armenia. New host plants are recorded for five species of tephritid flies: Centaurea polyphylla Ledeb. ex Nordm. and Amberboa glauca (Willd.) Grossh. for Acanthiophilus helianthi (Rossi, 1794), Lactuca orientalis (Boiss.) Boiss. for Hypenidium roborowskii (Becker, 1907), Reichardia dichotoma (DC.) Freyn for Trupanea amoena (Frauenfeld, 1857), Cladochaeta candidissima (M. Bieb.) DC. for Trupanea stellata (Fuessly, 1775), and Centaurea cheiranthifolia Willd. for Xyphosia laticauda (Meigen, 1826). The morphological details of all species of tephritid flies recorded here are illustrated in colour photos.

A new species of casebearer moths, Ecebalia zolotuhini sp. nov., is described from the Central Caucasus (Kabardino-Balkarian Republic, Russia).

A new species of Linothele Karsch, 1879 from southern Peru is described and illustrated, L. mubii sp. nov. The new species can be distinguished from other species of the genus by scopulation in combination with the morphology of copulatory organs.

A calcareous sponge Leucotreton kurilense gen. et sp. nov. (Sycanthidae) is described from the area of the Kuril Islands. It differs from all members of the family Sycanthidae in its aquiferous system, which is intermediate between leuconoid and sylleibid. Taxonomic status and nomenclature of several taxa formerly assigned to Sycanthidae is discussed. It is shown that the genus Dermatreton Jenkin, 1908 does not belong to Sycanthidae but this name is a senior synonym of Breitfussia Borojevic et al., 2000 (Jenkinidae), syn. nov.; Dermatreton contains three species previously included in Breitfussia: D. chartaceum Jenkin, 1908, D. schulzei (Breitfuss, 1896), comb. nov. and D. vitiosum (Brøndsted, 1931), comb. nov. It is shown that Tenthrenodes Jenkin, 1908 should be considered as a junior synonym of Sycon Risso, 1827, syn. nov. A new genus Scytotreton gen. nov. (Sycanthidae) is created to accommodate two species originally described in the genera Dermatreton and Tenthrenodes, respectively: Scytotreton hodgsoni (Jenkin, 1908), comb. nov. and S. scotti (Jenkin, 1908), comb. nov.

We describe a new species of the genus Acanthochitona Bergenhayn, 1930 from a group of small chitons inhabiting shallow waters of the South China Sea and near the Ryukyu Islands. The new species differs from others in this group in the presence of slightly flattened dorsal corpuscles with a narrow crest apically.

Philine malaquiasi Valdés, Cadien et Gosliner, 2016 is recorded from the Chukchi and Bering seas and from the southeastern coast of the Kamchatka Peninsula. This is the first record of the species for the Russian fauna. This species was initially considered as a member of the genus Philine Ascanius, 1772 (family Philinidae). In the present article, we transfer it to the genus Retusophiline Nordsieck, 1972 (family Laonidae) under the name Retusophiline malaquiasi (Valdés, Cadien et Gosliner, 2016), comb. nov., based on the morphology of the headshield, gizzard and copulatory system.

New records of eight species in the family Bibionidae are presented based on the material collected in Azerbaijan and Georgia in 2019. Six species were recorded for the first time for Transcaucasia, five species for Azerbaijan, and eight species for Georgia. In addition, the first checklist of Transcaucasian bibionids is given.

A new species of the genus Ornithomya Latreille, 1802 (Diptera: Hippoboscidae), O. strigilis sp. nov., is described from the Lazovsky Nature Reserve (southern part of Primorskiy Territory, the Far East of Russia). The new species differs from other Palaearctic species of Ornithomya in its large body size, the number of long setae on the scutellum, and the arrangement of microtrichia (setulae) on the wings. An updated key to the Palaearctic species of Ornithomya is provided.

A new chiton species, Lepidochitona granpoderi sp. nov., is described from the Atlantic coast of Morocco. It differs from other congeners in having 5–7 very short vestiges of ribs converging apically on the dorsal girdle corpuscules and longitudinal rows of granules converging to jugum in the central and antemucronal areas of the valves.

Scarlata namsanam sp. nov. from Laos is described and illustrated. The type series was collected on wet soil near the drying stream within a primary monsoon lowland tropical forest. This new species is most similar to S. guichardii Skowron Volponi, 2022, from which it differs in the coloration of the hind tibia, forewing and abdomen and in noticeably wider discal spot of the hindwing.

The genus Parascleroderma Kieffer, 1904 belonging to the subfamily Pristocerinae is recorded from Russia for the first time. Two new species of this genus are described and illustrated from males: P. astrakhanicum sp. nov. from the Astrakhan Province and P. austrouralicum sp. nov. from the Orenburg Province. A key for both Russian species is provided. Morphological differences of the pristocerine genera Parascleroderma and Foenobethylus Kieffer, 1913 are discussed.

A redescription of the Lake Baikal endemic species, Canthocamptus (Baicalocamptus) longifurcatus Borutzky, 1947 (Harpacticoida: Canthocamptidae), is provided. The illustrated redescription of morphology of the female and male is supplemented by a genetic barcoding based on sequences of the mitochondrial COI marker. Canthocamptus (B.) longifurcatus is morphologically very similar to another representative of the subgenus, C. (B.) verestschagini (Borutzky, 1931), but can be well distinguished from the latter by the armature of the female furca and the structure of the last pair of swimming legs in the female and male. An analysis of the obtained COI sequences and their comparison with those of other harpacticoid species confirmed that C. (B.) longifurcatus belongs to the genus Canthocamptus Westwood, 1836: the smallest genetic differences (on average, 29.5%) were observed between the studied Baikal species and C. staphylinus Jurine, 1820 from Europe (Lake Geneva, Switzerland).

Neohodgsonius kurochkini sp. nov., is described and illustrated based on material collected in Mexico. Neohodgsonius splendens Foldi, 2016 is transferred to Llaveiella Morrison, 1927 as Llaveiella splendens (Foldi, 2016), comb. nov. Neosteingelia texana Morrison, 1927 is recorded from Mexico for the first time. Cryptokermes oaxacoensis Foldi, 2011 is recorded from the Yucatan Peninsula for the first time and the ultimolarva of this species is fully illustrated.

Fifteen species of true bugs from the families Corixidae, Saldidae, Microphysidae, Anthocoridae, Miridae, Lygaeidae, Berytidae and Pentatomidae are recorded for the first time from the Urals. The studies cover the Polar, Subpolar, Northern, Middle and Southern Urals. For each species, collection data in the Urals and information on distribution in Russia and the world are given.

A new species of tephritid flies, Terellia hajastanica sp. nov., is described from Armenia. The new species belongs to the T. virens species–group and is characterised by the combination of entirely hyaline wing, orange spots on the katepisternum and meron, longitudinal orange stripe running from anterior spiracle through the anepisternum to anepimeron, and the glans of phallus similar in shape to that of T. arailerica Evstigneev, 2021. The phallus in both the species has a long tubular extension of the glans, with filaments separated from each other near the apex of extension. The glans of the new species is smaller, has a shorter portion of tubular extension between the rod and bifurcation of the filaments. The new species is similar to T. babaki V. Korneyev, 2017 from the T. amberboae species–group in the presence of orange stripe on the pleura. Larvae of the new species develop in the capitula of Centaurea pseudoscabiosa subsp. glehnii and pupate therein, whereas the larvae of T. arailerica develop in the capitula of C. spectabilis and pupate in their stems.

Limonia interjecta Starý, 1974 (Diptera: Limoniidae) previously known only from northern and central Europe is found from the Putorana Plateau in the north of Eastern Siberia. The species is recorded for the first time from Russia and the East Palaearctic. Limonia interjecta is rare in Europe but is quite common in the Putorana Plateau, with records in the boreal forest and tundra zones at altitudes from 71 to 723 m. An illustrated redescription of the male and female of L. interjecta is provided. Its distribution in the Palaearctic and habitats in the Putorana region are briefly discussed.

A new scale worm tentatively assigned to the genus Malmgrenia McIntosh, 1874 (Annelida: Polynoidae) is described from the burrows of callianassid shrimps belonging to the genus Gilvossius Manning et Felder, 1992 (Decapoda: Axiidea: Callianassidae). This is the first association involving callianassid shrimps with a polynoid scale worm, known from the Black Sea (northeastern basin) and even for the Atlantic Ocean basin. The taxonomy of the new species, as well as the previously known associations of scale worms with callianassid shrimps are also discussed.

A fossil tube of a polychaete from the family Serpulidae Rafinesque, 1815 was found during an expedition of the Zoological Institute of the Russian Academy of Sciences in 1998 in the western part of Sakhalin Island. The fossil is dated to the Middle–Late Miocene. There were no previous records of fossil serpulids in the area. Based on the examination of the morphology and microstructure of the tube, it was established that the fossil belongs either to the genus Chitinopoma Levinsen 1884 or to Filogranula (Langerhans, 1884) and is very similar to the tube of the species Chitinopoma rzhavskii (Kupriyanova, 1993) which currently inhabits the northeast of the Pacific Ocean.

The genus Greeffiella Cobb, 1922 includes twelve species inhabiting all oceans of the world. Updated brief and illustrated diagnoses, an identification key and data on the geographical and bathymetrical distribution of all Greeffiella species are given. Two new species are described and illustrated: G. japonica sp. nov. from the Sea of Japan and G. pontica sp. nov. from the Black Sea. The genus is recorded from the Sea of Japan for the first time, and G. japonica sp. nov. completes the list of the free-living nematode species inhabiting the shelf of the Far Eastern seas of Russia. This species is characterised by 70 annules dorsally and 62 ones ventrally, the ocelli located on the annules 19 and 29, somatic setae 11‒25 μm long, six pairs of subdorsal tubular setae on the body, the vulva surrounded by dense fine hair-like setae, located between the annulus 37 and 38, the tubular anus, and the terminal tube 10 μm long. Greeffiella pontica sp. nov. mentioned by the authors in 2021 as Greeffiella sp. was collected in the northwestern shelf of Crimea (the Black Sea) at a depth of 56 m and is characterised by the following characters: 67‒70 annules dorsally and 67‒68 ones ventrally, the absence of ocelli, somatic setae 12‒42 μm long, seven pairs of subdorsal tubular setae on the body, the vulva surrounded by short sparse setae, not visible anus, and the presence of three thin terminal tubes 13 μm long.

The paper reviews all available information on the species content, distribution and ecology of brackishwater hydrobiid snails belonging to the genus Caspiohydrobia Starobogatov, 1970. The annotated list of nominal species with remarks on their taxonomy, nomenclature and distribution is provided as well as photographic images of some type specimens and/or topotypes. In total, the genus includes 31 nominal species distributed almost exclusively within the former Paratethys basin. The lectotype for the species C. cylindrica Logvinenko et Starobogatov, 1969 is designated. A short overview of the known habitat preferences of various Caspiohydrobia species is provided. We consider Caspiohydrobia a genus of Ponto-Caspian origin, whose range extends southwards to Iraq, Iran and Tajikistan and northwards to West Siberia. The actual species content of the genus as well as its generic independence require a further integrative revision, since most of the nominal species of Caspiohydrobia are still known from dried shells only and may actually be synonyms of a few (or even a single) species.

The invasive stink bug species Halyomorpha halys (Stål, 1855) (Heteroptera: Pentatomidae), a dangerous pest of many agricultural plants, is recorded from Uzbekistan for the first time. Several imagines and larvae were found in the Khorezm and Ferghana provinces in 2020 and 2022.

The adventive species of scale insects Takahashia japonica (Cockerell, 1896) is recorded for the first time from eastern Europe, based on material collected on the Crimean Peninsula from the branches of Carpinus orientalis. The new drawing made in the modern technique and a brief morphological redescription of the adult female of the species is provided.