Mizuki Matsunuma’s research while affiliated with Kyoto University and other places

A taxonomic revision of the genus Apistus (family Synanceiidae), previously regarded as monotypic, including only Apistus carinatus (Bloch and Schneider 1801), resulted in the recognition of two species, including a new species from the Arabian Sea, Apistus shaula sp. nov. The following seven nominal species are regarded as junior synonyms of A. carinatus, as determined in previous studies: Apistus alatus Cuvier 1829, Apistus israelitarum Cuvier 1829, Parapistus marmoratus Steindachner 1866, Apistus evolans Jordan and Starks 1904, Apistus venenans Jordan and Starks 1904, Apistus faurei Gilchrist and Thompson 1908, and Apistus macrolepidotus Ogilby 1910. Apistus shaula sp. nov. is characterized by numerous black spots on the inner surface of the pectoral fins (absent in A. carinatus) and relatively longer 1st to 5th dorsal-fin spines compared with A. carinatus. Although Apistus balnearum Ogilby 1910 has been regarded as a junior synonym of A. carinatus, two juvenile syntypes possessed five mandibular barbels (three in Apistus) and were therefore identified as Apistops caloundra (De Vis 1886).

Two new perchlet species (Perciformes: Serranidae), Chelidoperca pulchella [3 specimens, 58.8–70.4 mm standard length (SL)] and Chelidoperca pollux (3 specimens, 68.1–72.3 mm SL), are described from Okinawa Island, Ryukyu Islands, Japan and Nha Trang Bay, Vietnam, respectively. Both new species are morphologically similar to Chelidoperca flavimacula Psomadakis, Gon and Htut 2021, described from the northern Andaman Sea, but can be readily distinguished from other congeners by the presence of many yellow spots on the anal fin, and three [2 full-sized and 1 (uppermost) half-sized] scales from the dorsal-fin base mid-point to the lateral line. However, the former differ primarily from C. flavimacula in having fewer yellow spots on the anal fin (2 or 3 spots on each membrane between the 3rd to 6th soft rays in the new species vs. 3 or 4 in C. flavimacula), and a single row of mandibular scales extending anteriorly from the angular onto the ventral surface of the dentary (vs. scales restricted to the angular in C. flavimacula). Chelidoperca pulchella is readily distinguished from C. pollux, the former having interorbital scales extending anteriorly beyond the mid-orbit (vs. ending at the mid-orbit), a deeper body (depth at pelvic-fin origin 25.8–26.4% of SL vs. 23.5–24.1% of SL), longer head (length 39.0–39.4% of SL vs. 35.6–36.3% of SL), larger eyes (orbit diameter 13.5–14.1% of SL vs. 11.0–11.7% of SL), and longer pectoral fins (length 27.8–29.8% of SL vs. 24.7–26.4% of SL). Since mitochondrial COI sequences from the type specimens of C. pulchella closely matched that of a specimen from the Philippines, the species may have a widespread distribution on the upper continental slope from the Ryukyu Islands to the Philippines.

A single specimen of Onigocia grandisquama (Regan, 1938) (Platycephalidae) from Kuantan, Pahang, Malaysia (east coast of Peninsular Malaysia) represents the first record of the species from Malaysia, previous records from the South China Sea having been restricted to Thailand. Four specimens of Soleichthys siammakuti Wongratana, 1975 (Soleidae) from Kuantan and Kota Kinabalu (Borneo), Malaysia and Negros (the Philippines) represent the first specimen-supported records of the species from those regions, the species having previously been collected only from the type locality (northern Gulf of Thailand).

Pseudorhombus elevatus Ogilby, 1912 and P. quinquocellatus Weber and de Beaufort, 1929 (Teleostei: Paralichthyidae) are newly recorded from Japan, based on 35 and two specimens, respectively, from Okinawa Island, Ryukyu Islands. Although both species have previously been recorded from Taiwan, no Japanese records are known to date. Pseudorhombus elevatus is characterized, and readily distinguished from Japanese congeners, by numerous minute teeth on both jaws, three dark blotches along the straight section of the ocular-side trunk lateral line, and dorsal- and anal-fin ray numbers. Pseudorhombus quinquocellatus resembles P. pentophthalmus Günther, 1862 and P. oculocirris Amaoka, 1969, all sharing five dark ocelli on the ocular-side body (two pairs of ocelli above and below the lateral line plus a single ocellus on the posterior portion of the lateral line). However, the former is characterized by strong caniniform teeth on both jaws (vs. no strong caniniform teeth in P. pentophthalmus and P. oculocirris); fewer lower gill rakers (9–11 in Japanese specimens) (vs. 15–21); and two dark skin flaps along the gill opening below the pectoral-fin base (vs. absent). The status of the type specimens of P. quinquocellatus was also considered, all three being regarded as syntypes, in the absence of a formal lectotype proposal. New standard Japanese names, “Maru-ganzō-birame” and “Niten-ganzō-birame,” are proposed for P. elevatus and P. quinquocellatus, respectively, the name “Itsutsume-ganzō” now being referred to P. megalops Fowler, 1934.

A taxonomic revision of the genus Centrogenys (family: Centrogenyidae), having previously been regarded as mono-typic (also monotypic family) represented by Centrogenys vaigiensis, resulted in the recognition of three species, including two new species from Australia, Centrogenys algrahami, new species, and Centrogenys pogonoskii, new species. The two other nominal species of the genus, Centropristes scorpenoides and Sebastes stoliczkae, were regarded as junior synonyms of C. vaigiensis. Centrogenys vaigiensis is readily distinguished from the two new species by lacking scale patches on the membranes between dorsal-fin spines (a small patch of scales present on each interspinous membrane of the third to last dorsal-fin spines in the two new species). Centrogenys algrahami, new species, is characterized by having fewer body scales, including 31-36 pored lateral-line scales (vs. 37-44 in C. vaigiensis and 39-46 in C. pogonoskii, new species) and 31-36 scale rows in longitudinal series (vs. 36-43 and 39-47), and a slightly greater number of pectoral-fin rays 14-16 (modally 15; vs. 12-15 [modally 14] in C. vaigiensis and C. pogonoskii, new species). Moreover, C. pogonos-kii, new species, is distinguished from the two congeners by the presence of squamation on the lateral side of the snout (in specimens .34 mm SL), whereas it is naked in the congeners. The status of the three species resulting from the morphological analysis was also strongly supported by molecular evidence of a partial sequence of the COI gene. Centrogenys vaigiensis is widely distributed in the Indo-West Pacific, ranging from Mauritius east to Indonesia and north to southern Japan. In contrast, Centrogenys algrahami, new species, and Centrogenys pogonoskii, new species, are restricted to Australia.

Two species of lefteye flounder (Bothidae), Engyprosopon mozambiquense Hensley, 2003 and Engyprosopon parvipectorale Amaoka and Ho, 2018, are newly recorded from Japan based on five specimens (one male and four females) and a single male specimen, respectively, from Nakagusuku Bay, Okinawa Island, Ryukyu Islands. The two species resemble each other in sharing the following combination of characters: extremely narrow interorbital space; large mouth (posterior margin of ocular side upper jaw extending beyond anterior margin of lower eye); inner margin of gill rakers with serrae; and a pair of dark blotches on caudal fin absent. However, the present male specimen of E. mozambiquense differed from male specimens of E. parvipectorale from Taiwan and Japan in having a greater interorbital width, 11.5 in head length (vs. 23.1-67.7 in male E. parvipectorale), a rostral spine on the ocular side of the snout (vs. absent), and three dark blotches on the ventral surface of the ocular side lower jaw (vs. uniformly black). The present female specimens of E. mozambiquense were characterized by having small teeth on both jaws (vs. anterior teeth on the upper jaw, and all teeth on the lower jaw large and canine-like in both male and female E. parvipectorale). The two species are also similar to the Japanese endemic congener, Engyprosopon kushimotoense Amaoka, Kaga and Misaki, 2008 (known only from the male holotype from Wakayama Prefecture), and Engyprosopon longipelvis Amaoka, 1969 (known from southern Japan) in having gill rakers with serrae and a narrow interorbital space. However, E. kushimotoense and E. longipelvis differ from the former in having 43 and 37-42 lateral-line scales, respectively (vs. 49-52 in E. parvipectorale and 46-52 in E. mozambiquense). The new standard Japanese names "Yorime-darumagarei" and "Kiba-yorime-darumagarei" are proposed here for E. mozambiquense and E. parvipectorale, respectively.

Pleuronectes chrysopterus Bloch and Schneider 1801 has previously been regarded as a putative junior synonym of Pseudorhombus arsius (Hamilton 1822) (Paralichthyidae). However, the holotype of the former was found to conform to the right-eye flounder genus Platichthys Girard 1854 (Pleuronectidae), and be most similar to the European flounder Platichthys flesus (Linnaeus 1758) and Baltic flounder Platichthys solemdali Momigliano, Denys, Jokinen and Merilä 2018 in having rough scales with bony tubercles distributed along the anterior portion of the body and along the dorsal- and anal-fin bases, exposed cycloid scales entirely covering the body, and 64 dorsal- and 44 anal-fin rays. Such a character combination set the holotype specimen apart from two northwestern Pacific congeners of Platichthys, which suggests that the originally stated type locality “Chinese sea” of Pleuronectes chrysopterus, may have been erroneous. Furthermore, the holotype has an unusually high number of pored lateral-line scales compared with all other species of Platichthys (123 vs. 60–90), possibly indicating that the holotype is a morphologically abnormal individual of a species of Platichthys or a hybrid individual of a species of Platichthys and another pleuronectid species in a different genus, with a high number of pored lateral-line scales.

Two new species of luminous roughies, Aulotrachichthys spiralis and Aulotrachichthys titan (Beryciformes: Trachichthyidae), are described, based on 32 specimens from three main islands of Japan (from Honshu, Shikoku, and southern Kyushu) and a single specimen from the Kyushu-Palau Ridge (northwestern Pacific Ocean), respectively. The holotype of A. titan was previously reported as Aulotrachichthys sajademalensis (Kotlyar 1979), a species restricted to the Western Indian Ocean, including off Somalia and the Saya de Malha Bank. Compared with congeners, the two new species are characterized by dorsal- and anal-fin spine and body scale numbers, shapes of the fin spines and interorbital ridges, relative lengths of the striated muscle band on the caudal peduncle, and several body proportions. These diagnostic characters in species of Aulotrachichthys are reviewed.

The new butterflyfish, Coradion calendula, is described on the basis of 44 specimens collected off Western Australia, the Northern Territory, and north Queensland, Australia. The new species is most similar to Coradion chrysozonus, with which it shares IX dorsal-fin spines, a single ocellated spot on the soft-rayed portion of the dorsal-fin, and a single dark band on the frontal surface of the thorax. The new species is distinguished from C. chrysozonus by slightly higher ranges of dorsal-fin soft rays 28–32, mode 29 (vs. 27–30, mode 28) and anal-fin soft rays 20–22, mode 21 (vs. 18–21, mode 20); an orange band on the caudal peduncle in fresh specimens (lost after preservation) with a saddle-like blackish dorsal streak (vs. a broad brown -to-black circumpeduncular band in both fresh and preserved specimens); a sharply pointed pelvic fin with an almost straight posterior contour when spread (vs. a rounded pelvic fin with an expanded posterior contour); and a dark band on each interopercle joining on the ventral midline, with their anterior margins forming a sharply pointed “V” in ventral view (vs. separated by a relatively wide interspace). Despite well-defined morphological and coloration differences, the mtDNA difference between the two species was relatively low, 0.8–1.9% (mean 1.3%) and 2.9–7.5% (mean 4.8%) pairwise sequence difference in COI and control region genes, respectively. Morphological and color-pattern characters and mtDNA lineage were not concordant in some specimens from northern Australia, where the two species overlap, suggesting that the two species hybridize at their common biogeographic borders.

Chelidoperca barazeri Lee, Lee, Matsunuma & Chen, 2019 is redescribed based on two sub-adult types and 12 additional non-types specimens collected from the type locality and southwestern Taiwan, respectively. The identification of the additional specimens were supported by morphological and/or molecular approaches. C. barazeri is characterized by the following combination of characters: three scale rows between lateral line and base of 6th dorsal-fin spine; pored lateral-line scales 34‒37, modally 36; modally 2+7 developed gill rakers on the upper and lower limb; soft dorsal fin with series of large yellow spots; and the anal-fin with a yellow margin. C. barazeri is most similar to C. tosaensis and can be distinguished from C. tosaensis by: relatively less pored lateral line scales, 34‒37 (vs. 37‒43, modally 39); anal-fin without series of spot; penultimate and the last dorsal- and anal-fin rays in adult not elongated (vs. well elongated in adults); presence of a faint and discontinuous stripe formed by clusters of melanophores along the mid-lateral body when preserved (vs. without or very indistinct). Furthermore, six species of Chelidoperca are confirmed occurring in the Taiwanese water by literature reviews. A key to Chelidoperca from the Taiwanese water is provided.