Taxonomic review of the genus Trisopterus(Teleostei: Gadidae) with recognition of the capelan Trisopterus capelanus as a valid species

Trisopterus is demonstrated to be monophyletic, including four distinct species: T. capelanus, T. esmarkii, T. luscus and T. minutus. The capelan T. capelanus is resurrected from the synonymy of poor cod T. minutus, and is shown to be morphologically more similar to T. luscus, to which species it is also more closely related, indicated by a phylogenetic analysis presented here. A lectotype is designated for T. luscus. Trisopterus fasciatus, the type species of Trisopterus, is a junior synonym of T. luscus, and the lectotype of T. luscus is designated as the neotype of T. fasciatus. The lectotype of T. luscus is also designated as the neotype of Gadus barbatus. Gadus barbatus has priority over T. luscus but the name is suppressed by prevailing usage of T. luscus. A neotype is designated also for T. minutus. A phylogenetic analysis using mitochondrial cytochrome b, and a fragment of the nuclear rhodopsin gene, shows that T. capelanus and T. luscus are sister species, and in turn sister to a clade formed by T. minutus and T. esmarkii.