Morphological differentiation of trout (subf. Salmoninae) based on characteristics of head skeleton

Abstract

Investigation of trout (subf. Salmoninae) for their continuous osteological characters of head that included analyses of elements from skull and visceral (jaws, gills and gill covers) bones revealed the unambiguous distinction between the autochthonous and admixed brown trout Salmo trutta stocks of the Danube River drainage area in Serbia for the characters on vomer, skull height, pterotic and premaxilar bones. Rainbow trout Oncorhynchus mykiss and Ohrid Lake's belvica trout Salmo (Salmothymus) ohridanus were also examined as outgroup taxa in order to understand better the overall variability and to reduce bias in the methodology applied. Belvica trout were more similar to the admixed than to the autochthonous brown trout populations, especially concerning the characters on the bones of the skull. Rainbow trout appeared clearly distinct from all brown trout (autochthonous and admixed) on their elements of skull (its height and width at the sphenotic level), being similar to the autochthonous brown trout on the elements of visceral skeleton, whereas on the elements of visceral skeleton, belvica trout were the most distinct from the brown trout and the rainbow trout, mainly due to the difference in the length of the premaxilar and maxilar bones. © 2011 Copyright 2011 Unione Zoologica Italiana.