Identification of loach fishes from Iran (Cypriniformes: Cobitoidea) using some osteological characters

Abstract This study examines eight skeletal features to distinguish species within the Cobitidae and Nemacheilidae families, focusing on the vertebral column, fin structure and caudal fin rays. The study analyses the construction and regionalization of the vertebral column, the interdigitation of pterygiophores with neural and haemal spines in the dorsal and anal fins, and the distribution of procurrent rays in the caudal fin. These characteristics are used to identify taxonomically relevant traits and separate species within these two families. The study also proposes a new method for defining vertebral column regions and presents new anatomical data for cobitoid species in Iran, including the division of the vertebral column into five regions: postcranial, abdominal (anterior and posterior) and caudal (anterior and posterior).