Artem Mikhailovich Prokofiev

A new species, Oneirodes logachevi sp. nova, is described. It is closely related to O. macrosteus but differs in the presence of a median escal appendage, a tall terminal papilla and the details of its pigmentation, the lack of distal branching of the anterior, anterolateral, and posterior escal appendages, but the presence of short secondary branches along the entire length of the posterior appendage. Oneirodes micronema, previously known only from two specimens of the type series from the Banda Sea, is recorded for the first time in the Atlantic Ocean. The new specimen differs from the type specimens primarily in the presence of branches on the anterolateral and median escal appendages, which may be associated with the individual variability.

Lycenchelys cyanosoma sp. nov. is described from a single specimen collected off the South Orkney Islands at 370–375 m depth. It can be easily distinguished from all known congeners by its lowest total vertebral count (76), dorsal- and anal-fin ray counts (71 and 54, respectively); unusual bluish coloration with blackish head; and the following additional features in combination: body fully scaled except the predorsal area but vertical fins completely scaleless; absence of oral valve, pseudobranchs and pyloric caeca; upper lip with pronounced flange; and periproct surrounded by peculiar tentacle-like processes. The new species is probably the smallest member of the genus, having developed testes at 98 mm standard length. Lycenchelys argentina, a rare and poorly-known species with a variable morphology, is herein redescribed based on a new (fourth known) specimen; we discuss the limits of its morphological variation. Lycenchelys cyanosoma sp. nov. and L. argentina may represent vicariant species with upper and lower bathyal/abyssal range, respectively. The diagnostically valuable features and known distribution of all Antarctic and Subantarctic Lycenchelys species are presented.

A new synonymy is established: Melanopopillia multisulcis Prokofiev, 2026 = Ischnopopillia angusta Lin, 1992. The similarity between I. angusta and M. praefica is treated as a morphological parallelism. Based on the similarity of their aedeagi, I. angusta and I. atronitens are considered basal members of Ischnopopillia. Ischnopopillia angusta is reported for the first time for the Sichuan Province. Установлена новая синонимия: Melanopopillia multisulcis Prokofiev, 2026 = Ischnopopillia angusta Lin, 1992. Сходство между I. angusta и M. praefica трактуется как параллелизм. По сходству в строении эдеагуса виды I. angusta и I. atronitens рассматриваются как базальная группа в составе Ischnopopillia. Вид I. angusta впервые отмечен для провинции Сычуань.

A new species, Melanopopillia multisulcis sp. nov., is described from the Sichuan province, P.R. China. It is most similar to M. praefica by the shape of impressions at base of elytra and by the absence of the carinate abdominal ventrites, but differs in the presence of seven (vs. five) complete elytral furrows between the humeral umbo and elytral suture, more sparse puncturation of the pronotum, and elongate parameres with tips hooked ventrally. The increased number of elytral furrows and the shape of parameres distinguish the new species from the all other known members of the genus. The genus Melanopopillia is reported for the first time for the Sichuan province. Описан новый вид Melanopopillia multisulcis sp. nov. из провинции Сычуань (КНР). Он проявляет наибольшее сходство с M. praefica по характеру вдавлений в основании переднеспинки и отсутствию килевого перегиба брюшка, но отличается от него семью (против пяти) полными бороздками надкрылий в промежутке между плечевым бугром и швом, более редкой пунктировкой переднеспинки и удлиненными парамерами, с вершинами клювовидно загнутыми вниз. Увеличенное число бороздок надкрылий и строение парамер выделяет новый вид среди всех известных представителей рода. Род Melanopopillia впервые отмечен для провинции Сычуань.

The results of the trawl survey of the research vessel Professor Kaganovsky over four seamounts (Annei, Jingu, Ojin, and Koko) of the Emperor Seamount Chain in 2019 are presented. Seventy-three species of pelagic and bottom-dwelling cartilaginous and bony fishes from 40 families were collected. Morphological diagnoses are presented for each species, with taxonomic comments for the poorly known taxa. The obtained collection includes 11 species new to science or of uncertain taxonomic position, 9 species newly reported for the Emperor Seamounts, and one new record Linophryne arborifera for the Pacific Ocean. For individual seamounts, 27 fish species were recorded for the first time at Annei, 12 species at Ojin, 4 species at Koko, and 2 species at Jingu Seamounts. Cytochrome c oxidase subunit I (COI) or cytochrome b (Cyt b) sequences were obtained for 36 species belonging to 22 families, including 13 species for which the barcode was flagged for the first time and the sequences made available. Cryptic diversity was revealed within the genera Cyclothone, Argyropelecus, and Chauliodus. According to our data, a boundary between the boreal and subtropical fish communities was found between Nintoku and Jingu Seamounts, with a transitional zone over Jingu and Ojin Seamounts at 37–39° N. However, the distribution of the subtropical species to the north may be limited by the increasing of summit depths in the northern subsection of the chain rather than any oceanographic or climatic barriers.

A new species of scaleless black dragonfish of the genus Eustomias, subgenus Spilostomias, is described based on a single specimen (96.4 mm SL) collected during the ABRACOS (Acoustics along the BRAzilian COaSt) expedition near the Fernando de Noronha Archipelago, off northeastern Brazil. Eustomias ansiluminis, new species, can be distinguished from Eustomias braueri, its only congener in the subgenus Spilostomias, by having two closely spaced cords of tissue that extend ventrally from the base of the barbel stem to the tip of the bulb as two thread-like filaments, which are partially loose by half of the bulb length, forming a loop-like structure around the bulb (vs. barbel without cords of tissue along its stem and below the bulb, but with a pair of simple and unbranched, minute to long filaments directly originated at the base of terminal bulb). Supplementary descriptions of E. braueri and E. macrurus, two insufficiently known species also collected during the ABRACOS expedition, are provided, and their global distributions are revisited based on the literature, databases, and additional specimens examined.

Psednos kaganovskii sp. nov. is described from the Emperor Seamount Chain. Based on fin ray and vertebral counts (39 dorsal and 35 anal fin rays, 47 total vertebrae), the new species belongs to the P. christinae species–group but differs from all other species in this group by the larger eye (35.7% of head length), heavily pigmented gastrointestinal duct, pectoral girdle structure, and a combination of other characters. This is the first record of the genus in the northwestern Pacific Ocean.

Ophthalmolycus lacrimegalos sp. nov. is described from a single specimen collected off the South Orkney Islands, Weddell Sea, Southern Ocean at a depth of 1,495 m. The new species differs from its congeners by the combination of extensive squamation covering the abdomen, predorsal area, and pectoral axil; an enlarged lachrymal bone, a wide bony interorbital space, and other characters (cephalic pore configuration, meristics, body proportions, coloration, etc.) in combination. This is the sixth species of the genus in the Antarctic waters, bringing the total number of known species in the genus to ten. However, the distinction of Ophthalmolycus in its current composition from the species-rich genus Lycenchelys requires elucidation. A revised key to the species of Ophthalmolycus is provided.

Gnathophis johnsoni sp. nov. is described on the basis of 15 specimens (138–380 mm TL) from the Emperor–Hawaiian Seamount Chain in the western and central North Pacific. The new species is most similar in morphology to G. bathytopos (Atlantic), G. cinctus (eastern Pacific), and G. smithi (Nazca and Salas-y-Gomez Seamounts in the southeastern Pacific) by the sensory pore configuration and vertebral count, but differs from these species in the following characters in combination: darkly pigmented pectoral fin, dorsal fin with black margin broadened caudally and extended onto the distal half of the caudal fin, relatively long head, jaws, gill slit and caudal fin, and on average a greater preanal distance. Although most of morphometrics overlap between the new species and its closest relatives, multivariate statistical analyses clearly discriminate this species. Molecular analysis shows sister relationships between the new species and G. cinctus, with 1.81% of genetic divergence, which significantly exceeds the differences between the haplotypes belonging to the same species (0.36 and 1.08% of divergence, usually not exceeding 0.9%) and confirms both species as close but distinct. The close relationship of G. johnsoni sp. nov. and G. cinctus represents a rare case of biogeographical relations between western and eastern Pacific demersal fish faunas. Molecular data suggest that some morphologically similar species may represent independently evolved lineages, though the group of Gnathophis possessing elevated lateral-line pores is likely monophyletic.