First Japanese record of Astronesthes gemmifer (Stomiidae: Astronesthinae) collected from the vicinity of the Ogasawara Islands, Japan

Abstract

The stomiid snaggletooth genus Astronesthes Richardson, 1845, including 49 valid species distributed in tropical to temperate waters of all oceans, is characterized by the following combination of characters: anal fin with 11–22 rays; maxillary teeth comblike, closely spaced, and slanting rearward; and photophores in the ventral series arranged in regular intervals. To date, 13 species of the genus have been reported from Japanese waters. A single specimen of Astronesthes (111.9 mm in standard length) was collected in December 2020, during a mid-water trawl survey conducted by R/V Shunyo-Maru in the vicinity of the Ogasawara Islands, Japan. Subsequently identified as Astronesthes gemmifer Goode and Bean, 1896, the specimen clearly differed from all congeners in having the following combination of characters: four premaxillary fangs in the main row (vs. 5–6); the posteroventral part of the terminal bulb of the chin barbel black (vs. usually not black or terminal bulb absent); and the last six VAV (photophores from the inner-pelvic space to the end of the row posterior to the anal-fin origin) located above the anal fin (vs. 1–4). Although A. gemmifer has been often recorded from the North Atlantic, records from the South Atlantic, Indian, and Pacific oceans are sparse. In the Pacific Ocean, the species has been recorded in Hawaiian waters from O‘ahu to the Hancock Seamounts, but not previously reported from Japanese waters, the present specimen representing the first Japanese record of A. gemmifer. The new standard Japanese name “Sumitsuki-tokagehadaka” is proposed for the species.