A preliminary revision of the Gobius auratus species complex with redescription of Gobius auratus27

Abstract

The study focused on two gobiid taxa from the northern Adriatic Sea. External features and coloration suggest identification of one of these with Gobius auratus Risso, 1810. This species is characterized by a deeply emarginated pelvic disc and meristic features of typically second dorsal fin rays I/14, anal rays I/13 and scales in lateral series 45. The live coloration of the northern Adriatic population shows a yellow basic coloration but with distinct longitudinal lines of red dots and, therefore, its colour significantly differs from the uniformly yellow coloration supposed to be typical for this species. A redescription of this putative G. auratus Risso, 1810 is carried out to extend the morphological characteristics of the species to cover also the northern Adriatic population. Two colour morphs are described and morphometrics as well as details on the lateral line system of the species are newly included in the species description. The second Adriatic taxon was assigned to G. fallax Sarato, 1889. Both taxa from the northern Adriatic were compared to G. xanthocephalus Heymer and Zander, 1992 from the western Mediterranean and Atlantic indicating their clear distinction. The northern Adriatic specimens of G. auratus show some similarities with the western Mediterranean and Atlantic G. xanthocephalus concerning life coloration, but differ in a series of features such as certain morphometrics (head and pelvic disc longer in the former, fifth pelvic ray, relative to fourth, longer in the latter), meristics (second dorsal rays mostly I/14 in the former and I/15 in the latter, anal rays mostly I/13 versus I/14, scales in lateral series about 45 versus 48). Gobius fallax is distinguishable by a different coloration pattern and shows the lowest values in mean fin and scale meristics. Phylogenetic analysis of DNA sequences of the first section of the control region revealed that all individuals of both colour morphs of G. auratus and of G. fallax form a single cluster of closely related haplotypes which are not sorted according to the species, suggesting their recent origin. Only G. xanthocephalus is, in agreement to morphology, also genetically distinct and represents a separate clade. The existence of a Gobius auratus species complex is therefore confirmed.