Abstract

A new octopus species,Callistoctopus tenuipessp. nov., was formally described from the southeastern coastal waters of China using morphological description and molecular analysis methods.C. tenuipessp. nov. is a small- to moderate-sized octopus, which is characterized by very narrow and long arms. Although it was previously misidentified as the juvenile ofOctopus minor(Sasaki, 1920), it can be recognised by spots, gill lamellae count, funnel organ shape, enlarged suckers, and ligula shape.C. tenuipessp. nov. differs from the small-sized octopusCallistoctopus xiaohongxu,mainly in the gill lamellae count, funnel organ shape, and arm-length index. In the molecular analysis, sequences obtained from the cytochrome c-oxidase subunit I (COI) gene of eight specimens were 590 bp in length. The pairwise Kimura 2-parameter (K2P) genetic distances between Octopodidae species ranged from 8.58 to 23.79% based on the COI gene. The phylogenetic analyses suggested thatC. tenuipessp. nov. belonged to theCallistoctopusclade and may have a close affinity withC. xiaohongxuandO.minor. Moreover, three species delimitation methods all strongly supportedC. tenuipesas a separate species.Keywords:Callistoctopus tenuipes;COI gene;morphological description;new species;taxonomy