Multilocus species delimitation analyses show junior synonyms and deep-sea unknown species of genus Gaidropsarus (Teleostei: Gadiformes) in the North Atlantic/Mediterranean Sea area.

Abstract Gaidropsarus Rafinesque, 1810 is a genus of marine teleost characterized by a high ecological diversity and by species inhabiting from the intertidal zone to the deep-sea. Several taxonomic conundrums have been historically present in this taxon due to its conservative morphology and the lack of available specimens. Species delimitation analyses were carried out in multiple datasets combining both mitochondrial (COI, CytB, ND2) and nuclear (Rho, ZIC1) genetic markers. Despite some incongruence between mitochondrial and nuclear data, the analyses supported the synonymy between Gaidropsarus biscayensis – Gaidropsarus macrophthalmus and the existence of a putative undescribed deep-sea Gaidropsarus species in the North Atlantic Ocean. Furthermore, recent speciation events can explain the close relationships among several Gaidropsarus species, including Gaidropsarus granti – Gaidropsarus vulgaris and Gaidropsarus argentatus – Gaidropsarus ensis. These results support previous findings highlighted through DNA Barcoding analyses. The first evidence of a complex evolutionary scenario has arisen between Gaidropsarus guttatus and Gaidropsarus mediterraneus, but further analyses will be necessary to unravel the phenomena related to it.