engleski

Identity od Squalius (Actinopterygii, Cyprinidae) from Istrian Peninsula in Croatia (Adriatic Sea basin)

A chub of previously ambiguous identity from the Boljunšćica and Pazinčica rivers (south-eastern Istra Peninsula) was studied and compared with geographically close Squalius squalus, S. zrmanja, and S. janae recently described from the Dragonja River drainage in the Adriatic Sea basin in Slovenia. It was shown that the chub from the south-eastern Istra Peninsula differs from all know species of Squalius but one: S. janae. Three samples examined from Boljunšćica and Pazinčica rivers and S. janae from its type locality, Dragonja River, show the following characters typical for the latter species: a long head (the head length 27–32% SL) ; a pointed conical snout with a clearly projecting upper jaw ; a long straight mouth cleft, the lower jaw length (39–45% HL) exceeding the caudal peduncle depth ; a large eye ; commonly 9½ branched anal-fi n rays ; commonly 44 total vertebrae (24+20 or 25+19) ; bright silvery colouration, scales easily lost ; iris, pectoral, pelvic and anal fi n pigmentation with yellow shades. The data on the distribution of Squalius chubs in the northern Adriatic basin support the assumption that the range of S. janae is determined by the geology of the Trieste Flysch Basin and the Pazin Flysch Basin forming the base of the Istra Peninsula. The distribution pattern of this species does not support a simple model of fish dispersal and a complete connectivity within the whole Palaeo-Po historical drainage. Indeed, it indicates a disrupted surface palaeohydrography that was heavily fragmented by karstification in the whole Dinaric area.

freshwater fish distribution; Cyprinidae; Istrian chub; Squalius; morphology; Adriatic Sea basin; Istra Peninsula; Slovenia; Croatia

nije evidentirano