Taxonomic review of the rare oarfish Regalecus russellii (Regalecidae: Lampriformes) from Korea using morphological and molecular methods

Abstract

One of the largest bony fishes on earth, the family Regalecidae is very rare. So, they remain largely unknown. They are often misidentified each other because they tend to be usually found in a damaged condition. Therefore, we firstly provide detailed morphological traits of R. russellii based on three voucher specimens (total length, 170–422 cm; damaged bodies) collected from Uljin, Ulsan and Jeju-do Island, Korea during 2018–2022. Based on color patterns, the numbers of dorsal fin rays, and gill rakers, our specimens were identified as R. russellii. The morphology of our specimens nearly matched that of the Eastern Pacific R. russellii. Molecular analysis based on mitochondrial DNA cytochrome c oxidase subunit I (506 bp) sequences showed that our specimens almost matched R. russellii recorded from Taiwan (Kimura-2-parameter distance = 0.44%). Our detailed morphological and molecular analysis results highlight the importance of voucher specimens to prevent misidentification.