Cranial osteology of the sand goby Neogobius fluviatilis (Pallas, 1881) from the River Sava (Serbia, Yugoslavia)

Abstract

The intrapopulation variability of the sand goby Neogobius fluviatilis (Pallas, 1811) from the River Sava mostly corresponds to the species intraspecific variability reported previously. Certain characters continuously increase through four examined size classes, while others increase most intensively in the largest size class, whereas the size of the suspensorial opening varies significantly, but irregularly. Allometry was not detected within the examined size range of sand gobies. There were no significant morphological differences between successive size classes. The influence of size on shape was negligible. The most variable trait, representing the metapterygoid process, varied stochastically, thus implying that it is of low interest for phylogenetic considerations. Other variable traits mostly describe elements of both upper and lower jaws and gill cover. The changes detected in skull elements (sphenotic and pterotic) are not strongly expressed, due to their small participation in the overall variability of the sample. It seems that gobies over 11 cm in total length are more diverse morphologically than those below that size.