Japanese scientists have described a new species of marine eeltail catfish in the genus Plotosus from southern Japan.
Naming the new catfish Plotosus japonicus, Tetsuo Yoshino and Hirokazu Kishimoto have published the description in a recent supplemental issue of the Bulletin of the National Museum of Nature and Science Series A. Zoology.
Plotosus japonicus is superficially very similar to, and has been previously confused with, the striped eel catfish (Plotosus lineatus), a species commonly found throughout the Indo-West Pacific.
Plotosus japonicus can be distinguished from other members of the genus in having a combination of the following: two or three pale stripes on body, of which two extend onto the head; a pair of dermal folds fringing the base of the dendritic organ; the nasal and maxillary barbels extending well beyond the posterior border of the orbit; the origin of the dorsal procurrent caudal-fin posterior to the vertical thorough the middle of the pelvic-fin base, and slightly anterior to the vertical through the origin of the anal fin; 20"26 rakers on the first gill arch; 142"174 rays in the confluent median fins; 48"52 vertebrae excluding the Weberian apparatus.
This species is found in the coastal waters of southern Japan (although the authors state that the Plotosus from the coastal waters of China and Korea might be this species) and is named after its distribution (Japan). Plotosus japonicus is found together with P. lineatus in the waters of southern Japan, but the two species can be distinguished by the fewer total rays in the confluent median fins (142"174 vs. 163"196), fewer gill rakers (20"26 vs. 25"31), and fewer free vertebrae (48"52 vs. 52"56) of P. japonicus.
For more information, see the paper: Yoshino, T and H Kishimoto (2008) Plotosus japonicus, a new eeltail catfish (Siluriformes: Plotosidae) from Japan. Bulletin of the National Museum of Nature and Science Series A. Zoology. Supplement 2, pp. 1"11.