First record of Tomiyamichthys oni (Actinopterygii, Gobiiformes, Gobiidae) from Ulleung Island, Korea

A single specimen (41.9 mm SL) of Tomiyamichthys oni (Tomiyama, 1936), representing the family Gobiidae, was firstly recorded from Ulleung Island, Korea on 1 March 2025. It was characterized by clusters of irregular brown spots covering its body, and a black band on lower part of opercle extending forward to tip of chin. The species is morphologically similar to Tomiyamichthys elliotensis Allen, Erdmann et Dudgeon, 2023, but distinctly different in the presence of small, irregular brown spots on the body (absence these spots in T. elliotensis).

In addition, T. oni was well distinguished from another four valid species in the genus Tomiyamichthys as determined by mitochondrial DNA cytochrome c oxidase subunit I gene (COI) sequence (546 bp) with genetic distances ranging from 0.130 to 0.252. In addition, this study reported a new northernmost record for the species at the latitude of 37 ° 27 ' N. A Korean name ‘ Geom-eun-tti-nun-se-u-mang-dug’ is herein proposed for the species.