相模湾から得られた北限記録のイズハナダイ属魚類 Plectranthias randalliチョウチョウハナダイ（新称）（ハタ科ハナダイ亜科）

抄録

During an ichthyofaunal survey of Sagami Bay, central Japan, a single specimen (95.9 mm standard length: SL) of the genus Plectranthias (Serranidae: Anthiadinae) was collected off Hatyama, Kanagawa Prefecture, by line-fishing at a depth of 130 m over rocky substrate, on 6 April 2024. Subsequently identified as Plectranthias randalli Fourmanoir and Rivaton, 1980, the specimen had the following combination of characters: dorsal-fin rays X, 16; pectoral-fin rays 13–14, all rays branched except uppermost and lowermost rays; lateral line complete, with 37–39 pored scales; total gill rakers 20; posterior margin of preopercle with 42–44 serrae, entire ventral margin smooth; body deep, 45.2% of SL; third dorsal-fin spine longest; snout scaleless except maxilla covered with scales; two oblique broad red bands on lateral surface of body; single narrow red band from lateral surface of eye to thorax; a single small red blotch on upper portion of caudal-fin base. In addition, the specimen had 10 + 16; supraneurals 3, all similar in length; 6–7 subopercle serrae on posterior margin; 4–5 interopercle serrae on posterior margin; 5–9 serrae on posttemporal; and 6–8 serrae on lacrimal lower margin. The species has been previously recorded from the Coral Sea, Indonesia, and Taiwan, the present specimen, possibly transported by the Kuroshio Current from Taiwan or more southerly waters during the planktonic stage, representing the first Japanese record and northernmost record for the species. The new standard Japanese name “Chocho-hanadai” is proposed for P. randalli, based on the present specimen.