著者
Shizuma Yanagisawa Shimpei F. Hiruta Yositaka Sakamaki Satoshi Shimano
出版者
The Japanese Society of Systematic Zoology
雑誌
Species Diversity (ISSN:13421670)
巻号頁・発行日
vol.26, no.2, pp.145-151, 2021-06-17 (Released:2021-06-17)
参考文献数
23

A new species from the cockroach genus Eucorydia Hebard, 1929 from Miyako-jima Island of the Nansei Islands in Southwest Japan was compared to six closely related congeners; E. yasumatsui Asahina, 1971; E. donanensis Yanagisawa, Sakamaki, and Shimano, 2020; E. tokaraensis Yanagisawa, Sakamaki, and Shimano, 2020; E. dasytoides (Walker, 1868); E. guilinensis Qiu, Che, and Wang, 2017; and E. pilosa Qiu, Che, and Wang, 2017. The new species Eucorydia miyakoensis Yanagisawa, Sakamaki, and Shimano, sp. nov. from Miyako-jima Island was characterized by a small overall male body length of 12.5–13.0 mm and tegmina with an uninterrupted orange transversal band in the middle, and a pair of orange pubescent patches at the base. Eucorydia yasumatsui, E. donanensis, E. tokaraensis, the zonata population of E. dasytoides, and E. miyakoensis were divided into five lineages in a maximum likelihood tree generated from a dataset concatenated from five molecular markers (two nuclear: 28SrRNA and histone H3, and three mitochondrial: COII, 12SrRNA, and 16SrRNA). We recognized E. miyakoensis as a distinct species, which was also supported by the pairwise genetic distances (3.4%–6.7%, K2P) of the COI sequences to the other Japanese Eucorydia species.
著者
Tobias Pfingstl Shimpei F. Hiruta Takamasa Nemoto Wataru Hagino Satoshi Shimano
出版者
The Japanese Society of Systematic Zoology
雑誌
Species Diversity (ISSN:13421670)
巻号頁・発行日
vol.26, no.1, pp.93-99, 2021-03-22 (Released:2021-03-22)
参考文献数
21
被引用文献数
2

We describe a new species of marine associated oribatid mite, Ameronothrus twitter Pfingstl and Shimano, sp. nov., from a wharf of fishing port (Choshi Outer Fishing Port), Chiba, Honshu, Japan. This species was spotted for the first time ever on photographs posted on Twitter. Ameronothrus twitter Pfingstl and Shimano, sp. nov. is characterized by a specific cuticular notogastral pattern consisting of distinct nodules that are fused to irregular ridges in the median anterior and the median posterior region. Additionally, it features a unique combination of fused lamellar keels, presence of primilateral setae on tarsus I, presence of dorsal companion setae on genu I, II, III and all tibiae and tarsal distal setae ending with a small nodule. Ameronothrus twitter Pfingstl and Shimano, sp. nov. is the second species of this genus found on Japanese islands, which represents the southernmost occurrences of this taxon in the Asian Pacific region.
著者
Naoto Sawada Haruhiko Toyohara Takafumi Nakano
出版者
The Japanese Society of Systematic Zoology
雑誌
Species Diversity (ISSN:13421670)
巻号頁・発行日
vol.26, no.2, pp.217-224, 2021-09-10 (Released:2021-09-10)
参考文献数
22
被引用文献数
1

Sodium hypochlorite has been used for cleaning specimens of freshwater and brackish water snails that are covered with deposits. Our experiments using specimens of two freshwater snail species, Semisulcospira niponica (Smith, 1876) and S. reticulata Kajiyama and Habe, 1961, showed that this traditional method could remove thin deposit layers, including algae, but was not useful for obstinate deposits. We found that a new method using ammonium thioglycolate could be applied to remove obstinate iron-rich deposits. Though ammonium thioglycolate treatment caused loss of gloss inside the aperture, this loss could be prevented by plugging a kneaded eraser into an aperture. Moreover, the new method could clean specimens with little damage of the periostracum. So as to remove deposits with the least damage to shells, 3% w/v sodium hypochlorite was useful for deposits including algae, and 20% w/v ammonium thioglycolate was suitable for cleaning specimens with iron-rich deposits. Degeneration of the microstructure of inner whorls can be avoided by plugged shell apertures with a kneaded eraser in both methods. Shell deposits that are composed of both algae and iron should be treated first with 20% w/v ammonium thioglycolate, and then with 3% w/v sodium hypochlorite to remove the deposits. Appropriate cleaning methods enable accurate examination and long-term preservation of shell specimens.
著者
Shizuma Yanagisawa Yositaka Sakamaki Sopark Jantarit Satoshi Shimano
出版者
The Japanese Society of Systematic Zoology
雑誌
Species Diversity (ISSN:13421670)
巻号頁・発行日
vol.26, no.2, pp.191-195, 2021-08-06 (Released:2021-08-06)
参考文献数
7

Specimens of the genus Eucorydia Hebard, 1929 from Chiang Mai, northern Thailand, were compared with eight closely similar congeners: E. aenea (Brunner von Wattenwyl, 1865), E. dasytoides (Walker, 1868), E. yunnanensis Woo, Guo, and Feng, 1986, E. pilosa Qiu, Che, and Wang, 2017, E. guilinensis Qiu, Che, and Wang, 2017, E. tangi Qiu, Che, and Wang, 2017, E. linglong Qiu, Che, and Wang, 2017, and E. tokaraensis Yanagisawa, Sakamaki, and Shimano, 2020, and turned out to be a different species from eight congeners. This species from Thailand is characterized by the specific male genitalia shape: right phallomere 2 (R2) slightly elongated, the basal left area of R2 forming a triangular protrusion, and the basal half of left phallomere 7 (L7) protruded to the left with long spatulate distal half and with a beak-like apex. This species is also characterized by the tegmina containing three orange markings in the middle, and with a pair of orange markings at its base. Based on the above, this species is described as a new species, Eucorydia asahinai sp. nov.
著者
Tomohiro Kita Kazuki Matsushige Shunsuke Endo Noritaka Mochioka Katsunori Tachihara
出版者
The Japanese Society of Systematic Zoology
雑誌
Species Diversity (ISSN:13421670)
巻号頁・発行日
vol.26, no.1, pp.31-36, 2021-03-05 (Released:2021-03-05)
参考文献数
25

Six specimens of Anguilla luzonensis Watanabe, Aoyama, and Tsukamoto, 2009 were collected from Okinawa-jima Island, Okinawa Prefecture, southern Japan. This species was previously known from Luzon Island, Mindanao Island and Taiwan. Therefore, the present specimens represent the first records of A. luzonensis from Japan and extend the northern distribution limit of the species. A new standard Japanese name, “Uguma-unagi”, is proposed for the species.
著者
Yusuke Hibino Kaoru Kuriiwa Tetsuya Yamada Kiyotaka Hatooka Kar Hoe Loh Tetsuro Sasaki
出版者
The Japanese Society of Systematic Zoology
雑誌
Species Diversity (ISSN:13421670)
巻号頁・発行日
vol.25, no.2, pp.177-182, 2020-08-07 (Released:2020-08-07)
参考文献数
12

Four specimens from Minami-iwo-to island of Volcano Islands were identified as Uropterygius oligospondylus Chen, Randall, and Loh in Loh et al., 2008. It is the first identified record from Japan and the northernmost record of the species. Uropterygius oligospondylus can be characterized by the following characters: total vertebrae 100–103; body gray with blackish reticular pattern; jaws teeth in two or three rows; anus close to mid-body; head 13.7–16.7% TL; trunk 32.8–36.6% TL; body depth at gill opening 5.8–8.3% TL; eye diameter 3.9–5.3% of head length; snout 16.2–20.3% of head length; and presence of a distinct notch above mid-eye. A new Japanese standard name “Kobu-kikai-utsubo” is proposed for the species. The position of the fourth infraorbital pores from original description should be revised as “far behind posterior end of eye”.
著者
Mizuki Sasaki Jason Lee Anders Minoru Nakao
出版者
The Japanese Society of Systematic Zoology
雑誌
Species Diversity (ISSN:13421670)
巻号頁・発行日
vol.26, no.2, pp.255-272, 2021-09-10 (Released:2021-09-10)
参考文献数
135
被引用文献数
2

The cestode fauna of murid and cricetid rodents in Hokkaido, the northernmost island of Japan, was evaluated based on our parasite collection and a review of the literature. Adult and larval cestodes collected from Apodemus speciosus (Temminck, 1844), Myodes rufocanus (Sundevall, 1846), and Rattus norvegicus (Berkenhout, 1769) in Hokkaido were identified by both morphological and molecular diagnoses. A total of 10 species from 5 families were confirmed in our collection. Arostrilepis tenuicirrosa Makarikov, Gulyaev, and Kontrimavichus, 2011, Paranoplocephala kalelai (Tenora, Haukisalmi, and Henttonen, 1985), and Taenia crassiceps (Zeder, 1800) were recorded for the first time from Hokkaido. A comprehensive look at both the present and previous studies revealed that the cestode fauna of rodents in Japan consists of at least 30 species from 6 families. Among them, 23 species occur in Hokkaido. The species composition is strongly affected by the nearby Eurasian continent, suggesting parasite migrations with rodent hosts over land bridges between Hokkaido and Sakhalin and between Hokkaido and Honshu, the main island of Japan. A DNA barcoding system using sequences of nuclear 28S rDNA and mitochondrial cox1 allowed us to identify cestodes at species and genus levels, even in different developmental stages. The integration of morphological and molecular diagnoses is essential in cestode taxonomy to establish a common ground for biogeographical studies worldwide. The standardization of DNA barcoding is particularly of critical importance.
著者
Minoru Nakao Mizuki Sasaki Tsukasa Waki Mitsuhiko Asakawa
出版者
The Japanese Society of Systematic Zoology
雑誌
Species Diversity (ISSN:13421670)
巻号頁・発行日
vol.24, no.2, pp.159-167, 2019-07-25 (Released:2019-07-25)
参考文献数
35
被引用文献数
3

Members of the genus Glaphyrostomum Braun, 1901 (Trematoda: Brachylaimidae) are parasites of birds. However, an exception occurs in Glaphyrostomum soricis Asakawa, Kamiya and Ohbayashi, 1988, which was described from the long-clawed shrew, Sorex unguiculatus Dobson, 1890, in Hokkaido, Japan. A recent DNA barcode-based trematode survey of land snails clearly showed that Ainohelix editha (A. Adams, 1868), a bradybaenid snail indigenous to Hokkaido, serves as the first and second intermediate hosts for a species of the genus Pseudoleucochloridium Pojmańska, 1959 (Panopistidae). Its adult stage was furthermore confirmed from S. unguiculatus. A comparison of adult morphology between Pseudoleucochloridium sp. and G. soricis revealed that both should be considered the same species. However, Pseudoleucochloridium soricis comb. nov. cannot be applied because P. soricis (Sołtys, 1952) already exists as the type species of the genus. We, therefore, propose Pseudoleucochloridium ainohelicis nom. nov. as a replacement name for G. soricis.
著者
Yuya Suzuki Haruki Tatsuta
出版者
The Japanese Society of Systematic Zoology
雑誌
Species Diversity (ISSN:13421670)
巻号頁・発行日
vol.27, no.2, pp.319-328, 2022-10-13 (Released:2022-10-13)
参考文献数
23

Two new gnaphosid spider species, Cladothela bicolor Suzuki, sp. nov. and Micaria longimana Suzuki, sp. nov. are described on the basis of both sexes, from material collected in the Okinawa Islands in the Ryukyu Islands, Japan. Illustrations and photographs of both species, as well as a map of the sampling locations are provided.
著者
Yusuke Hibino
出版者
The Japanese Society of Systematic Zoology
雑誌
Species Diversity (ISSN:13421670)
巻号頁・発行日
vol.23, no.2, pp.219-223, 2018-11-25 (Released:2018-11-25)
参考文献数
5

A new finless ophichthid eel, Apterichtus soyoae, is described based on a single specimen collected from off Tori-shima island, Zunan Islands of Izu Islands, southern Japan. The new species is similar to A. moseri and A. klazingai in its numbers of supratemporal pores, preopercular pores, and vertebrae. The new species differs from A. moseri in having more supraorbital pores (1+6 vs. 1+4), the number of branchings of the supraorbital canal (1 vs. 0), shape of the snout (distinctly pointed vs. relatively blunt), eye size (50% of snout length vs. 35–45%; 8.8% of head length vs. 6.3–8.0%), and the number of vomerine teeth (1 vs. 2–5). Apterichtus soyoae can also be distinguished from A. klazingai by the number of branchings of the supraorbital canal (1 vs. 2), the number of infraorbital pores (7 vs. 9), and the location of the lower jaw tip (anterior to a vertical through anterior margin of eye vs. posterior to the vertical). The number of supraorbital pores and branchings of the canal are discussed.
著者
Hiroshi Nakamine
出版者
The Japanese Society of Systematic Zoology
雑誌
Species Diversity (ISSN:13421670)
巻号頁・発行日
vol.27, no.1, pp.91-94, 2022-03-25 (Released:2022-03-25)
参考文献数
15

Perlomyia gakken sp. nov. (Plecoptera: Leuctridae) from Kyoto Prefecture, Honshu, Japan, is described and illustrated. This new species is distinguished from all other Perlomyia species by having a remarkably long and slender epiproct with a crochet hook shape at tip. Although, this new species is most similar to P. kappa Sivec and Stark, 2012, but can be discriminated from P. kappa by the three morphological differences: (1) cercus with small spine-like apex (long terminal spine in P. kappa), (2) epiproct slightly swollen at middle in lateral aspect (swollen basally in P. kappa), and (3) epiproct like a crochet hook shape apically in lateral aspect (expanded apically in lateral aspect in P. kappa). A checklist and type localities map for 25 currently recognised Perlomyia species are also presented.
著者
Jason D. Williams Christopher B. Boyko Takeya Moritaki
出版者
The Japanese Society of Systematic Zoology
雑誌
Species Diversity (ISSN:13421670)
巻号頁・発行日
vol.27, no.2, pp.227-241, 2022-07-21 (Released:2022-07-21)
参考文献数
41
被引用文献数
1

In this paper, we describe two new species of dajid isopods found enveloping the antennules of decapod hosts: Akrophryxus acinaces sp. nov. parasitizing Pycnoplax surugensis (Rathbun, 1932) (off Pacific coast of central Japan, approximately 200 m depth) and A. pallipalicus sp. nov. parasitizing Parapalicus armatus Castro, 2000 (South China Sea, approximately 410 m depth). Females of both species exhibit the characteristic spheroid shape found in the genus Akrophryxus Williams and Boyko, 2021. Females of the three species in Akrophryxus can be distinguished by several characters, including form of the pleon and oostegite 5. Males can be distinguished by head/pereomere 1 to pereomere 2 ratio and posterolateral margin shape, and pereopod 6 dactylus and ischium size. The three species of Akrophryxus not only differ in morphological characters but parasitize species belonging to three different heterotreme brachyuran families. The first described cryptoniscus larval stage for any species in the genus is described for A. acinaces sp. nov. We also describe a new cryptoniscoid, Chimaeroniscus spheramator gen. et sp. nov., the first hyperparasite described from any dajid host (A. pallipalicus sp. nov. on the host Pa. armatus). This hyperparasite is a putative egg predator of its dajid host and exhibits a unique combination of generic level characters including: pleon markedly narrower than pereon, antennule with large teeth on basal segment and with setal brush, 3 or 4 coxal teeth on all pereomeres, pereopods 3–7 isomorphic and dissimilar from pereopods 1 and 2, telson with smooth distomedial projection, and uropodal exopods half-length of endopods. Finally, we address some taxonomic issues within Cryptoniscoidea, moving two genera (Neritoniscus Schultz, 1977 and Cryptocisus Schultz, 1977) known only by cryptoniscus larval characters from Cryptoniscoidea incertae sedis to Dajidae and synonymize Cryptonus Schultz, 1977 with Holophryxus Richardson, 1905.
著者
Ken Maeda Toshifumi Saeki
出版者
The Japanese Society of Systematic Zoology
雑誌
Species Diversity (ISSN:13421670)
巻号頁・発行日
vol.23, no.2, pp.253-262, 2018-11-25 (Released:2018-11-25)
参考文献数
37
被引用文献数
2

Amphidromous gobies of Sicyopterus (Gobiidae: Sicydiinae) are distributed in tropical, subtropical, and temperate streams in the Indo-Pacific region. Two species, Sicyopterus japonicus (Tanaka, 1909) and Sicyopterus lagocephalus (Pallas, 1770), are known from Japan. In the present study, two specimens of an additional species were collected in Okinawa Island, in southern Japan. We compared morphologies of the type series of Sicyopterus longifilis de Beaufort, 1912 and Sicyopterus brevis de Beaufort, 1912 collected in Indonesia, with the specimens from Okinawa Island to revise the taxonomy of these species and to identify the Okinawan specimens. Syntypes of S. longifilis and S. brevis share many characters, including a unique mouth morphology. Although fin morphologies, tooth number, and the shape of the urogenital papilla differ between S. longifilis and S. brevis syntypes, these amount to normal sexual dimorphism of sicydiine gobies. De Beaufort collected his specimens at the same locality on the same date. We conclude that the syntypes of S. longifilis and S. brevis are actually males and females of same species. Therefore, they are subjective synonyms, and we give precedence to the name S. longifilis as the first reviser under Article 24.2 of the International Code of Zoological Nomenclature (International Commission on Zoological Nomenclature 1999). The two specimens from Okinawa Island were identified as S. longifilis and this is the first record of this species from Japan.
著者
Taiga Kunishima Herminie P. Palla Katsunori Tachihara Ken Maeda
出版者
The Japanese Society of Systematic Zoology
雑誌
Species Diversity (ISSN:13421670)
巻号頁・発行日
vol.27, no.1, pp.129-138, 2022-04-15 (Released:2022-04-15)
参考文献数
48

Twenty specimens of Acentrogobius ocyurus (Jordan and Seale, 1907) were collected in Manko, Okinawa-jima Island, Japan and Sulu Sea side of Puerto Princesa City, Palawan Island, Philippines. As the species had previously been reported from the South China Sea, Andaman Sea, and northern Australian waters, these specimens from Okinawa and Palawan represent the first records of the species from Japan and the Sulu Sea. Acentrogobius ocyurus was found on muddy substrata at the lowest tidal zone of the mudflat and was often found in burrows of mangrove pistol shrimp, Alpheus richardsoni Yaldwyn, 1971. Morphological traits suggested that A. ocyurus is closely related to A. globiceps (Hora, 1923), A. kranjiensis (Herre, 1940), and Acentrogobius sp. (“Suzume-haze” in Japanese name), with several homologous features including, the transverse pattern of the sensory papillae on the cheek, caudal fin pointed in middle, a black stripe behind the eye along the anterior oculoscapular canal, bright blue spots laterally on the body, and an oblique yellow stripe across the upper part of the caudal fin.
著者
Yoshiaki Kai Akinori Otani Ryo Misawa Benjamin W. Frable Fumihito Tashiro
出版者
The Japanese Society of Systematic Zoology
雑誌
Species Diversity (ISSN:13421670)
巻号頁・発行日
vol.27, no.2, pp.285-292, 2022-10-13 (Released:2022-10-13)
参考文献数
25

Two specimens of a rare deep-sea anglerfish, Himantolophus azurlucens Beebe and Crane, 1947, were collected off the Pacific coast of northern Japan, representing the first records from the western North Pacific. These specimens represent the second and third records of the species since the original description, which was based on a single specimen from the eastern North Pacific; we determined that a previous record from the Atlantic was erroneous. We herein provide a description of the specimens and comments on intraspecific variation of the escal appendages. The new Japanese name “Masamori-chouchin-anko” is proposed for H. azurlucens. In addition, we provide DNA barcode sequences of the recently collected specimens of Himantolophus Reinhardt, 1837, including H. azurlucens and the fourth record of H. borealis Kharin, 1984, and demonstrate remarkably low intraspecific genetic variation of cytochrome c oxidase subunit I within the genus.
著者
Tomohiro Yoshida Shigeru Harazaki Hiroyuki Motomura
出版者
The Japanese Society of Systematic Zoology
雑誌
Species Diversity (ISSN:13421670)
巻号頁・発行日
vol.24, no.2, pp.189-193, 2019-09-25 (Released:2019-09-25)
参考文献数
10

Two specimens (68.8–72.3 mm standard length) of Ostorhinchus chrysotaenia (Bleeker, 1851), previously recorded from Indonesia, northwestern Australia, Papua New Guinea, Solomon Islands, northern Borneo, Philippines, and Taiwan, and recently collected off Yaku Island, Osumi Islands, Kagoshima Prefecture, Japan, represent the first records of the species from Japan supported by voucher specimens, and the northernmost distributional record of the species. The holotype and an additional non-type specimen of O. chrysotaenia were determined from two Bleeker specimens registered under the same catalog number.
著者
Taiga Kunishima Ken Maeda Ryutei Inui Yusuke Hibino
出版者
The Japanese Society of Systematic Zoology
雑誌
Species Diversity (ISSN:13421670)
巻号頁・発行日
vol.26, no.2, pp.343-349, 2021-10-14 (Released:2021-10-14)
参考文献数
34
被引用文献数
1

A single specimen of Muraenichthys gymnopterus (Bleeker, 1853) was collected from a sandy intertidal flat having rocks and dead corals in the estuarine area of Nagura Amparu, Ishigaki-jima Island, southern Japan, in October 2020. This specimen collection constitutes the first record of M. gymnopterus from Japanese waters. In this study, the diagnostic characters between M. gymnopterus and M. hattae Jordan and Snyder, 1901 are provided, based on our morphological observations of 37 specimens, including Okinawan specimen, and previous studies, as follows: head length [M. gymnopterus 11.8–15.0% of total length (TL) vs. M. hattae 9.4–11.0%], trunk length (24–25.4% of TL vs. 28–31%), the horizontal distance from the dorsal-fin origin to a vertical line through the anus 73–87% of head length vs. 13–49%), the number of vertebrae (total 129–130 vs. 148–155; predorsal 30 vs. 47–53; preanal 41–44 vs. 51–55), the number of the lateral-line pores before the anus (43–45 vs. 51–55). Additionally, the body depth at the gill opening in TL and the trunk length in TL can also be used to distinguish between these two species (2.8–3.7% of TL vs. 1.4–3.0%). Although M. gymnopterus has previously been reported from tropical to temperate regions, we suspect that the records from temperate regions are based on misidentification of M. hattae.
著者
Makoto Okamoto Kouji Matsuda Tamaki Matsuda
出版者
The Japanese Society of Systematic Zoology
雑誌
Species Diversity (ISSN:13421670)
巻号頁・発行日
vol.15, no.3-4, pp.131-138, 2010-12-30 (Released:2018-03-30)
参考文献数
33
被引用文献数
1 1

A pelagic juvenile (43.0mm standard length) of the morid Gadella jordani (Bohlke and Mead, 1951) was collected from Kagoshima Prefecture, southern Japan. It has a characteristically elongated body, long dorsal and anal fin bases with 73 rays in each fin, the anus located more anteriorly than the origin of the second dorsal fin, a ventral light organ, and no chin barbel. We describe the morphology of this specimen and also present a color photograph of it in life. This is the first report of any early life stage in this species.
著者
Ko Tomikawa Yuji Abe Takafumi Nakano
出版者
The Japanese Society of Systematic Zoology
雑誌
Species Diversity (ISSN:13421670)
巻号頁・発行日
vol.24, no.2, pp.259-266, 2019-11-25 (Released:2019-11-25)
参考文献数
10
被引用文献数
4

A new species of pseudocrangonyctid amphipod, Pseudocrangonyx uenoi, is described from cave streams in Taga town, central Honshu, Japan. Previous molecular phylogenetic studies reported the taxonomic status of the Taga populations of Pseudocrangonyx as an undescribed species. We present the diagnostic features to discriminate P. uenoi from the other congeners on the basis of morphological study. Pseudocrangonyx uenoi is closely related to P. daejeonensis Lee, Tomikawa, Nakano, and Min, 2018, but clearly distinguished from the latter by the presence of calceoli on female antenna 2, the 5-dentate lacinia mobilis of the left mandible, setation of the peduncular articles of pleopods, the number of articles of rami of the pleopods, a shorter terminal article of uropod 3, and a telson with a deeper cleft.
著者
Fumihito Tashiro Yusuke Hibino Kei Miyamoto
出版者
The Japanese Society of Systematic Zoology
雑誌
Species Diversity (ISSN:13421670)
巻号頁・発行日
vol.22, no.2, pp.213-217, 2017-11-25 (Released:2017-12-05)
参考文献数
10
被引用文献数
3

An old museum specimen of the rare deep-sea species Ophichthus exourus McCosker, 1999 (Anguilliformes: Ophichthidae) (685 mm in total length) collected near Saipan and a recently collected example from Okinawa, Japan (634 mm in total length) represent the first Northern Hemisphere records of the species, previously known only from the southwestern Pacific in waters off New Caledonia and Fiji, but now believed to be widely distributed in the western Pacific Ocean. A detailed morphological observation based on the above specimens and a re-examination of the holotype resulted in a revision of some species characteristics, including the number of infraorbital pores. Ophichthus exourus is distinguished from other congeners by the following combination of characters: head 8.3–10.0% of total length; upper jaw 36.1–38.1% of head length; pectoral-fin rounded, length 19.2–24.1% of head length; rear margin of eye above or slightly behind rictus; eye diameter 44.4–61.2% of snout length; horizontal length of posterior nostril dermal flap much greater than diameter of anterior nostril tube; gill opening to dorsal-fin origin greater than twice pectoral-fin length; preopercular pores 2; predorsal and total vertebrae 20–21 and 173–177, respectively; lower-jaw teeth nearly uniserial; body without bands or spots; posteriormost portion (much shorter than head length) of anal-fin membrane indistinct darkish brown. A new standard Japanese name “Gunbai-umihebi” is proposed for the species.