The morphology and biology of Gonatus tinro and Gonatopsis okutanii (Teuthida: Gonatidae) indicate that they are conspecific

Katugin, O. N., Shevtsov, G. A., and Zuev, M. A. 2010. The morphology and biology of Gonatus tinro and Gonatopsis okutanii (Teuthida: Gonatidae) indicate that they are conspecific. – ICES Journal of Marine Science, 67: 1464–1477. Distribution, size and maturity patterns, and ontogenetic changes in morphological characters of the squid species Gonatus tinro and Gonatopsis okutanii were examined. The database includes information collected during research surveys to the Sea of Okhotsk and the adjacent Northwest Pacific Ocean from 1972 through 2005. Both species are distributed within the same areas beyond the shelf: G. tinro within a wide range of depths and an active vertical migrant, G. okutanii mostly demersal, characteristic of many adult gonatids. Seasonal changes in size and maturity of G. tinro and G. okutanii are congruent in many respects: G. tinro are usually small and young with hookless tentacle clubs, and squid identified as G. okutanii tend to be larger adults with truncated tentacles. The comparative morphology of the two species and the discovery of individuals bearing external features of both indicate that G. okutanii is an adult stage and G. tinro a young stage of the same species. It is concluded that G. okutanii is a junior synonym of G. tinro, which becomes the valid name by precedence.