engleski

Morphological differences in some Cobitis populations from Croatia. Loaches of the Genus Cobitis and Related Genera.

Most of the Cobitis species from the area of south Europe are briefly described by Karaman, 1929, without morphometric data, figures and descriptions of some specific morphological characters.Also, long-term genetic and other investigations showed that the so-called ~common loach", until recently considered as polytypic Cobitis taenia species, is in fact the complex of many reproductively isolated species, a large number of them with restricted range of distribution. Based on these facts it was necessary to redescribe the population from this area. The analyzed populations were taken from the Adriatic river basin(rivers Zrmanja, Cetina and Neretva) together with one population from the Danube river basin (river Drava). The methods of analysis comprised classical truss network morphometry, meristic parameters and also some mophological characters. The values of the truss network morphometry showed bimodal distribution for populations from Cetina and Zrmanja, which point to the possible existence of the two subpopulations in these rivers. For the Cetina loaches this is supported with two types of lamina circularis and suborbital spines in both sexes. Meristic characters like the number of vetebrae showed a similarity between populations of the Cetina and Neretva and populations from the Zrmanja and Drava. Maximal number of eggs showed similarity between populations from the Cetina and Drava (3300 eggs) but not in the size of eggs. In the latter, a character similarity exists between the Neretva and Drava loaches. T-test for the truss network values showed little differences between populations from the Cetina and Neretva, but the population from the Zrmanja is highly different from other populations. Sexes observed separately by this method showed that males from the river Drava are different from males from the Cetina and Neretva in almost all values, while females showed. The methods of analysis comprised classical truss network morphometry, meristic parameters and also some mophological characters. The values of the truss network morphometry showed bimodal distribution for populations from Cetina and Zrmanja, which point to the possible existence of the two subpopulations in these rivers. For the Cetina loaches this is supported with two types of lamina circularis and suborbital spines in both sexes. Meristic characters like the number of vetebrae showed a similarity between populations of the Cetina and Neretva and populations from the Zrmanja and Drava. Maximal number of eggs showed similarity between populations from the Cetina and Drava (3300 eggs) but not in the size of eggs. In the latter, a character similarity exists between the Neretva and Drava loaches. T-test for the truss network values showed little differences between populations from the Cetina and Neretva, but the population from the Zrmanja is highly different from other populations. Sexes observed separately by this method showed that males from the river Drava are different from males from the Cetina and Neretva in almost all values, while females showed The methods of analysis comprised classical truss network morphometry, meristic parameters and also some mophological characters. The values of the truss network morphometry showed bimodal distribution for populations from Cetina and Zrmanja, which point to the possible existence of the two subpopulations in these rivers. For the Cetina loaches this is supported with two types of lamina circularis and suborbital spines in both sexes. Meristic characters like the number of vetebrae showed a similarity between populations of the Cetina and Neretva and populations from the Zrmanja and Drava. Maximal number of eggs showed similarity between populations from the Cetina and Drava (3300 eggs) but not in the size of eggs. In the latter, a character similarity exists between the Neretva and Drava loaches. T-test for the truss network values showed little differences between populations from the Cetina and Neretva, but the population from the Zrmanja is highly different from other populations. Sexes observed separately by this method showed that males from the river Drava are different from males from the Cetina and Neretva in almost all values, while females showed. These results suggest the possible hybridization between the populations from the Danube and Adriatic river basins. Clusters made for the classical morphometry showed a similarity among Adriatic populations. Clusters for the truss network morphometry showed results obtained by t-test. Phenotypic characters showed that all four populations are different and recognizable from the each other. Adriatic populations have an awry position of upper caudal fin base spots, and they are brown to dark brown while the Drava population has a jet black spot. Populations of Zrmanja and Neretva have two of them, but in the Neretva population the lower one is less visible. The shape of mouth and barbels showed that in the loaches form Cetina and Zrmanja barbels are very long, but in the Zrmanja population they are also thin and pigmented. Comparison with the Sweden holotype material described by Nalbant, 1993, showed that the populations from Croatia are different. Two spots at the base of caudal fin in Zrmanja population point to similarity with the Italian C. t. bilineata Canestrini, 1865 from river Po basin, and loaches from the Drava are similar to C. t. danubialis Bacescu, 1993 from Romania. Also loaches from Cetina and Neretva, until now considered as a subspecies of the Cobitis taenia, should be raised on the species level. Future genetic investigations are necessary to support this theory.

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