First Japanese records of the redtail scad Decapterus kurroides (Carangiformes: Carangidae), from Kumano-nada (Pacific coast of Mie Prefecture) and the East China Sea

The carangid genus Decapterus Bleeker, 1851 is characterized by single finlets behind both the second dorsal and anal fins, no scutes along the anterior curved part of the lateral line, two low papillae on the shoulder girdle, and a well-developed adipose eyelid. Members of the genus are distributed in tropical to temperate areas of the Pacific, Indian and Atlantic oceans, and are commercially important food fishes. Four species (D. akaadsi Abe, 1958, D. kurroides Bleeker, 1855, D. smithvanizi Kimura, Katahira and Kuriiwa, 2013 and D. tabl Berry, 1968), characterized by a red caudal fin, are included in the red-fin Decapterus group. In 2016 and 2018, three specimens [216-304 mm in standard length (SL)] of D. kurroides, previously recorded from the Red Sea and east coast of Africa to the east coast of Australia and the Philippines, were collected from Kumano-nada, Pacific coast of Mie Prefecture, Japan. Additionally, a single specimen (191 mm SL) collected from Japanese waters in the East China Sea (west of Kyushu) in 2006 was also identified as D. kurroides. The specimens represent the first records of the species from Japanese waters, the Kumano-nada specimens being the northernmost record for the species. Decapterus kurroides is the most similar to D. akaadsi, but differs from the latter in the following characters: scutes more numerous on the straight part of the lateral line (30-32 vs. 26-29 in D. akaadsi), longer head (head length 29.9-33.0% SL vs. 26.7-30.1%) and longer snout-anus distance (55.8-60.4% SL vs. 51.2-54.6%) [measurements for both species modified from Kimura et al., (2013)]. Decapterus kurroides is also distinguishable from D. smithvanizi and D. tabl by having fewer cycloid scales on the curved part of the lateral line (45-52 vs. 54-62 in D. smithvanizi, 61-72 in D. tabl) and a deeper body (body depth 23.4-27.2% SL vs. 19.4-22.5%, 16.6-23.0%). A new standard Japanese name "Kitsune-akaaji" is proposed for D. kurroides.