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| Opistognathus ctenion Fujiwara, Motomura & Shinohara, 2023 |
Abstract
Opistognathus ctenion sp. nov. (Perciformes: Opistognathidae) is described on the basis of three specimens (17.3–30.6 mm in standard length) collected from the Osumi and Ryukyu islands, southern Japan in depths of 35–57 m. Although most similar to Opistognathus triops, recently described from Tonga and Vanuatu, the new species differs in mandibular pore arrangement, dorsal- and caudal-fin coloration, fewer gill rakers, and lacks blotches or stripes on the snout, suborbital region and both jaws.
Key words: Actinopterygii, dredge, new species, Osumi Islands, Ryukyu Islands, taxonomy
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| Opistognathus ctenion Fresh coloration of two paratypes A, C KAUM–I. 174226, 30.6 mm SL; B, D KAUM–I. 174227, 26.2 mm SL A, B lateral views; C, D dorsal views. photographed by KAUM |
Opistognathus ctenion sp. nov.
New English name: Japanese White spotted Jawfish
New standard Japanese name: Shiratama-agoamadai
Diagnosis: A species of Opistognathus distinguished from congeners by the following combination of characters: posterior end of upper jaw rigid, without flexible lamina; dorsal-fin rays XI, 16–18; anterior dorsal-fin spines very stout and straight, and their distal ends not transversely forked; anal-fin rays II, 17; gill rakers 6 or 7 + 13 or 14 = 20 or 21; vertebrae 10 + 22 = 32; longitudinal scale rows c. 40–50; lateral line terminating below 4th–6th soft ray of dorsal fin; 4th and 5th mandibular pore positions usually included 2 and 6–7 pores, respectively; body scales absent anterior to vertical below 4th or 5th dorsal-fin spine; vomerine teeth 2; body reddish-brown with 3 or 4 longitudinal rows of c. 8–10 whitish blotches; cheek and opercle with five or six whitish blotches; snout, suborbital region, and both jaws without blotches or stripes; spinous dorsal fin with ocellus between 2nd to 5th spines; dorsal-fin soft-rayed portion with two reddish-orange stripes; pectoral-fin base with one or two whitish blotches; caudal fin uniformly faint orange or reddish-yellow.
Etymology: The specific name is a noun in apposition derived from the Greek diminutive κτενίον, meaning “a small comb”. It refers to the low gill raker numbers in the new species, one of the lowest recorded for Indo-Pacific species of Opistognathus (see below).
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| Distributional records of Opistognathus ctenion. |
Kyoji Fujiwara, Hiroyuki Motomura and Gento Shinohara. 2023. Opistognathus ctenion (Perciformes, Opistognathidae): A New Jawfish from southern Japan. ZooKeys. 1179: 353-364. DOI: 10.3897/zookeys.1179.109813
