Redescription and first Japanese seamount record of Stethopristes eos (Zeiformes; Parazenidae).

During a biodiversity survey conducted in 2020, focusing on seamounts located in the southern region of Japan, specifically designated as marine protected areas, a single specimen of Stethopristes eos Gilbert, 1905 measuring 124.2 mm in standard length was obtained via the use of a remotely operated vehicle (ROV). The collection occurred at a depth of 519 meters on the Ritto Seamount, located along the western Mariana Ridge. However, this species is poorly known, with only a limited dataset available concerning its morphology. In this study, we present a comprehensive redescription of the species, utilizing information obtained from the type specimens and a newly discovered specimen from Japanese waters. The Japanese specimen constitutes the first recorded occurrence of this species within the western Pacific Ocean. As part of this redescription, we suggest new standard Japanese names for both the genus and species.

First eumonostiliferous nemertean from the Nishi-Shichito Ridge, Genrokunemertes obesa gen. et sp. nov. (Eumonostilifera, Nemertea).

Nemerteans are mostly marine, benthic invertebrates, inhabiting intertidal to hadal zones. Recently, they have been recognized from deep sea with environmental DNA (eDNA) metabarcoding of sediment samples whereas any records from the locations and/or the water depth have not been documented in nemertean taxonomic publications to date. It suggests that there are major gaps between deep-sea nemertean fauna observed with eDNA and taxonomic knowledge. During a research expedition in 2021, we obtained a single specimen of eumonostiliferous nemertean from the southern part of Genroku Seamount Chain, the Nishi-Shichito Ridge, where any nemertean species have never been reported. Subsequent morphological and molecular examination reveal that the species is placed in a new genus and herein described as Genrokunemertes obesa gen. et sp. nov. It resembles shallow-water-dwelling Kurilonemertes and Typhloerstedia, but differs from the former in lacking eyes and the latter in possessing well-developed cephalic glands and lacking accessory nerves of lateral nerve cords. In terms of genetic distances based on partial sequences of the cytochrome c oxidase subunit I gene, G. obesa gen. et sp. nov. is closest to Monostilifera sp. Owase collected from Japan, which is characterized by large four eyes; the COI distance is higher than commonly observed interspecific divergences in eumonostiliferans.

Nighttime migrations and behavioral patterns of Pempheris schwenkii.

BACKGROUND: Although the biomass of the nocturnal fishes is almost same as that of diurnal fishes, most of the ecological studies that examine feeding or reproductive behaviors are on diurnal fishes. Therefore, there is limited ecological information regarding the nocturnal fishes. This fact may be attributed to the difficulty in observing them during darkness. Members of the genus Pempheris (Pempheridae) are one of the most abundant nocturnal fishes on coral reefs. METHODS: The nighttime migrations of Pempheris schwenkii were observed by attaching a chemical luminescent tag. Tagged fishes were followed by an observer without torch and SCUBA, and their positions and estimated depths were plotted on an underwater topographic map. Aquarium tank observation was carried out to further describe their habits during the night. RESULTS: The new tagging method provided good data for observing the migration behavior. In all five observations, the target fishes started nighttime migration from the entrance of their cave within 1 h after sunset. All of them immediately left the inner reef and spent most of the observation time near the surface (0-5 m depth) or shallow (5-15 m depth) water-columns of the outer reef. Their migration pattern varied between days, but they migrated long distance (379-786 m/h) during each observation. The behavior observed in the aquarium tank was categorized into five patterns: schooling, shaking, migrating, spawning, and feeding. Shaking and spawning were observed during one of three observation days. DISCUSSION: The present study firstly clarified the small-scale but dynamic nocturnal migration pattern of P. schwenkii in nature by a new method using chemical luminescent tags. In addition, combined observations from nature and an aquarium could be used to estimate the behavior of this species. Pempheris schwenkii may reduce their predation risk of eggs and adults by spawning at outer reef in nighttime. It was estimated that they can potentially migrate 4-7 km/night. The rapid growth known for this species may have been supported by their feeding behavior where they can fill up their stomach every night with rich zooplankton in outer reefs. Furthermore, the behavior of this species indicates the possibility that they make an important contribution to the flow of energy and materials in their coral reef ecosystem.

Photonectes banshee, a new species of the subgenus Photonectes (Stomiiformes: Stomiidae: Melanostomiinae) from Taiwan.

A new scaleless dragonfish, Photonectes (Photonectes) banshee sp. nov., (Stomiiformes: Stomiidae: Melanostomiinae) is described from three specimens collected from off southwestern Taiwan. The new species can be distinguished from its congeners in the subgenus in having unique counts of photophores: IP, ventral series anterior to pectoral-fin base (6 vs. 7-13), VAV, ventral series from just behind ventral-fin base to just behind anal-fin origin (10 vs. 11-16) and VAL, lateral series from just behind ventral-fin base to just behind anal-fin origin (9 vs. 11-15) and the following combination of characters: relatively more dorsal- and anal-fin rays, lacking white luminous tissue on dorsoposterior opercle, and the presence of blue luminous tissue on mid-ventral.

A new pearlfish, Onuxodon albometeori sp. nov. (Ophidiiformes: Carapidae), from Taiwan.

Onuxodon albometeori sp. nov. (Ophidiiformes: Carapidae) is described from a single specimen collected by commercial trawl off southwestern Taiwan. The new species is most similar to the Indo-Pacific species Onuxodon fowleri (Smith 1955), both process a remarkably slender body, and higher precaudal vertebral counts and a longer pectoral fin, although the two latter features are even more extreme in the former. Onuxodon albometeori sp. nov. is further distinguished from O. fowleri by its lesser body depth, greater head width, higher counts of precaudal vertebrae, and uniformly whitish coloration only on the posterior part of the body.

Redescription of Tetragonurus pacificus (Teleostei: Stromateoidei: Tetragonuridae), based on specimens collected from Taiwan and Tarawa Atoll.

The rare squaretail Tetragonurus pacificus Abe 1953 was described on the basis of a single poor-condition specimen obtained from the stomach of a yellowfin tuna collected from west of the Solomon Islands. A fresh specimen of T. pacificus was recently collected from southwestern Taiwan and its morphology and the fresh coloration are herein described in detail. In addition, a juvenile specimen collected from the southern Pacific Ocean was found in the museum collection. The species is characterized by dorsal-fin spines 10-11; longitudinal scale rows along body axis 72-80; and predorsal scales 17-20. The present specimen collected from off southwestern Taiwan represents the northernmost record of the species from the Pacific Ocean.

A new Malthopsis batfish from Taiwan, with comments on Malthopsis tiarella Jordan, 1902 (Lophiiformes: Ogcocephalidae).

A new species of the triangular batfish genus Malthopsis Alcock, 1891 is described on the basis of 9 specimens collected from off Taiwan. The new species belongs to a species group with ventral surface covered by numerous small prickle-like bucklers. It differs from the members in this species group in having ventral surface entirely covered with tiny bucklers; principal bucklers on dorsal surface relatively tall, few in number and loose in arrangement; subopercle dull without enlarged forward-directed spine; rostral spine directed forward horizontally; 5 dorsal-fin rays and 12 pectoral-fin rays; and posterior tip of appressed anal fin not reaching caudal-fin base. Two specimens of Malthopsis tiarella Jordan, 1902 collected from Taiwan are recognized and its diagnosis is discussed.

Redescription of Liopropoma aragai (Teleostei: Serranidae), with two new confirmed records of species of Liopropoma from Taiwan.

Liopropoma aragai Randall Taylor 1988 is redescribed based on the holotype and non-type specimens from Japan and Taiwan. Diagnostic characters of the species and the status of Taiwanese specimens previously referred to L. aragai are reassessed. Liopropoma lemniscatum Randall Taylor 1988, previously recorded only from the Pacific coast of Japan and the Ryukyu Archipelago, and L. lunulatum (Guichenot 1863), previously known from Okinawa Island (Japan), Guam, Réunion, Rarotonga and Tahiti, are redescribed, both being confirmed for the first time by voucher specimens from Taiwanese waters. A detailed description of each species and a key to Taiwan Liopropoma Gill 1861 is provided.

Review of the genus Eustomias (Stomiiformes: Stomiidae: Melanostomiinae) of Taiwan, with descriptions of three new species.

The barbeled dragonfish genus Eustomias in Taiwan is reviewed. Five species in three subgenera are recognized, including three new species, a new record, and an unidentified species. Eustomias (Dinematochirus) dendrobium sp. nov. can be distinguished from its congener by its unique barbel structure. Eustomias (Haploclonus) stamen sp. nov. has a unique barbel structure and diagnostic meristic characters. Eustomias (Nominostomias) tritentaculatus sp. nov. has an extremely long barbel and distinct pigmentation, with fin ray counts that are different from most similar species. Eustomias (Nominostomias) perplexus Gibbs, Clarke Gomon 1983, widespread in the western Pacific Ocean is reported for the first time from Taiwan. Three specimens of Eustomias were only identifiable to subgenus Haploclonus due to their poor condition.

An unexpected distribution record of the cold water fish Pholis fangi (Pholidae) from southern Taiwan.

Gunnel species (family Pholidae), characterized by an elongated bar-like body and usually found in shallow coastal waters, are mostly restricted to temperate to subarctic waters in the Northern Pacific Ocean, although some in the Western Pacific are distributed southward to the northern East China Sea. Despite the absence of previous records from subtropical and tropical waters, a single specimen of the fish family Pholidae was recently trawled off southwestern Taiwan. Examination on the morphological characteristics and DNA barcoding revealed this is a Pholis fangi (Wang Wang 1935), a species previously recorded only from cold waters in the Bohai and Yellow seas. As a consequence, the present specimen represents the first record of the species from the subtropical South China Sea coast of Taiwan, as well as an isolated southernmost record of this species, more than 1,000 km southward from the otherwise known distribution. Detailed morphology and fresh coloration are described.

A new Portholefish of the genus Diplophos (Stomiiformes: Gonostomatidae) from the western Pacific Ocean.

A new Portholefish, Diplophos vicinia sp. nov., is described on the basis of nine specimens collected from the western Pacific Ocean by commercial midwater trawl. The new species, currently known only from the South China Sea and north of Papua New Guinea, can be easily distinguished from six nominal congeners by the combination of the following characters: dorsal-fin origin closer to snout than caudal-fin base, distance between last two AC photophores half that between preceding photophores, gill rakers 4 + 10-11=14-15, abdominal vertebrae 30-32, caudal vertebrae 44-45, total vertebrae 74-76, and the following photophore counts: IP 13-14, PV 18-19, IV 31-32, VAV 12-13, AC 37-39 + 2, and IC 83-86.

A new garden eel, Heteroconger fugax (Congridae: Heterocongrinae), from the northwestern Pacific Ocean.

Heteroconger fugax sp. nov. (Congridae: Heterocongrinae) is described from a single specimen collected from Amami-oshima island, Japan. The new species is most similar to Heteroconger tomberua Castle Randall 1999, known from Fiji and New Caledonia, in having a remarkably slender body with numerous small spots and a vertebral count close to 200. However, it can be distinguished from H. tomberua by the presence of a large distinct white blotch on the opercle; more numerous, dense spots over the entire head, including lips; ground color of body uniformly cream, without microscopic melanophores; numerous small conical cirri on the chin; and dorsal-fin origin located more posteriorly to appressed pectoral-fin tip. A survey of underwater photographs of Heteroconger on photographic database revealed H. fugax to be widely distributed in the northwestern Pacific Ocean, from the Ryukyu Archipelago to Borneo.

A review of the genus Pempheris (Perciformes, Pempheridae) of the Red Sea, with description of a new species.

Four species of the fish genus Pempheris are recognized for the Red Sea: P. adusta Bleeker, 1877; P. mangula Cuvier, 1829; P. nesogallica Cuvier in Cuvier & Valenciennes, 1831; and a new species P. tominagai. All are wide-ranging in the western Indian Ocean, and P. mangula has migrated via the Suez Canal to the eastern Mediterranean Sea. Morphological and genetic analysis of 15 species in this genus show that P. adusta, a widely distributed species, that can't be divided into different species, because of the continuity of morphologies and distribution, and lack of variance in genetics between Indian Ocean, Red Sea, and Pacific Ocean populations. This confirms that the two subspecies described by Randall et al. (2013) are both synonyms of P. adusta. Pempheris adusta is distinguished from other species by a blackish spot on pectoral fin base, pored lateral-line scales 56-64, scale rows above lateral line 4 1/2-6 1/2, distinct blackish band on outer edge of anal fin, and blackish band on posterior edge of caudal fin. Pempheris mangula was named by Cuvier (1829) in a footnote making reference to a drawing and short description in Russell (1803) of a Pempheris from southeast India, giving only the native name ''Mangula-Kutti'', and listing no specimen. The wide distribution of this species, from the Indian Ocean to the Red Sea is also demonstrated by morphological and genetic analysis. Thus, the specimen collected from southern India is herein designated as the neotype. This species is distinguished from other species by its huge eye, deep body, blackish tip of the dorsal fin, pored lateral-line scales 49-60, and scale rows above lateral line 4 1/2-5 1/2. The extant syntype of Kossmann & Räuber's P. rhomboidea is designated as the lectotype of the species; however, P. rhomboidea is a synonym of P. mangula. In addition, Kossmann & Räuber's Pempheris erythraea and P. russellii Day, 1888 are also synonyms of P. mangula. Of two existing syntypes of P. nesogallica from Mauritius, one is designated as the lectotype, the other is re-identified as P. mangula; P. nesogallica is presently known only from the southern Red Sea. This species has a similar morphology to P. mangula, but can be distinguished by a smaller eye than P. mangula, and lack irregular faint longitudinal light stripes on the body side. Pempheris tominagai are distinguished from P. schwenkii Bleeker 1855, formerly misidentified, by the form of posterior nostril, scale counts, color of caudal fin, and by a 2.1% mitochondrial DNA sequence divergence. 

Pempheris ufuagari sp. nov., a new species in the genus Pempheris (Perciformes, Pempheridae) from the oceanic islands of Japan.

Pempheris ufuagari sp. nov. is described based on 10 specimens, 143.9-196.8 mm in standard length, collected from Mi-nami Daito Island and Ogasawara Islands, which are oceanic islands of Japan. Pempheris ufuagari is characterized by a distinct black spot on the pectoral fin base, a bright yellow dorsal and caudal fin, and a blackish band on the outer margin of the anal fin. Pempheris oualensis also has a large body and a distinct black spot on the pectoral fin base, and forms mixed schools with P. ufuagari, but can be distinguished by the different fin coloration (dorsal and caudal fin brown or pale; no blackish band on anal fin margin), and the presence of a villiform tooth band extending outside the lips. Although P. otaitensis, which is found in French Polynesia and Samoa, has similar coloration as P. ufuagari, the latter has lower scale counts than those of the former species: pored lateral-line scales 62-71 (vs. 70-79); scale rows above lateral line 6 1/2-7 1/2 (vs. 8 1/2); predorsal scales 37-43 (vs. 44-48).