A new species of Sebastes (Scorpaeniformes: Sebastidae) from the northeastern Pacific, with a redescription of the blue rockfish, S. mystinus (Jordan and Gilbert, 1881)

The diverse predatory rockfishes (Sebastes spp.) support extensive commercial fisheries in the northeastern Pacific.Although 106 species of Sebastes are considered valid, many of the ecological, geographical, and morphological boundaries separating them lack clarity.We clarify one such boundary by separating the blue rockfish Sebastes mystinus (Jordan and Gilbert, 1881) into 2 species on the basis of molecular and morphological data.We redescribe S. mystinus, designate a lectotype, and describe the deacon rockfish, Sebastes diaconus n. sp.Aside from its unambiguous distinction at 6 microsatellite loci, the new species is most easily differentiated from S. mystinus by its possession of a solid in contrast with a blotched color pattern.Sebastes diaconus also possesses a prominent symphyseal knob versus a reduced or absent knob, a flat rather than rounded ventrum, and longer first and second anal-fin spines.Sebastes diaconus occurs from central California northward to British Columbia, Canada, and S. mystinus occurs from northern Oregon south to Baja California Sur, Mexico, indicating a broad region of sympatry in Oregon and northern California.Further collection and study are necessary to clarify distributional boundaries and to understand the ecology and mechanisms of segregation for this species.Additionally, fisheries assessments will need revision to account for the longstanding conflation of these 2 species.