Contribution to the morphology and distribution of the Balkan loach Cobitis elongata Heckel et Kner, 1858.

Cobitis elongata Heckel et Kner, 1858 in Croatia inhabits the Sava River basin including the Kupa, Petrinjcica and Ilova Rivers and the Buzeta and Utinja streams. We were interested to find if there are some differences in the morphological characters between two spatially isolated populations inhabiting two closely located streams, the Kupa River and its right tributary the Petrinjcica River. Sampling was carried out in June and july 2003 by electrofishing. Body pigmentation, under the lower lip ˝barbells˝ form as well as form and size of suborbital spine were determined for 18 fresh specimens of C. elongata from the Kupa River and 8 fresh specimens from the Petrinjcica River. Morphometric (28 characters) and meristic (11 characters) characters were taken the standard methods on 23 specimens from the Petrinjcica River and 22 from the Kupa River. Pearson´s correlation matrices wereused to determine the degree of correlation between fundamental morphometric measurements and stepwise multiple regression analysis in order to explain the total variation of Sl. ANOVA was used to test the differences in measurements between the Kupa River and Petrinjcica River. Coefficient of difference (CD) was used as a difference scale in morphological characteristics of analysed populations. Using the coefficient of difference we have determined differences between populations on the subspecies and species level (CD value of 1.28 has been admitted from many authors as the bottom margin for the subspecies determination). Direct measurements (mm) were used for calculating correlations and regression analysis. The SPSS 12.0 software was used for all statistical procedures. We found significant morphological differences between specimens inhabiting the Kupa River and those from its right tributary the Petrinjcica River. These differences are caused by the spatial isolation of these two populations due to artificial and natural barriers on the Petrinjcica River. Difference coefficient indicates that these two populations can not be considered a subspecies.