Interspecific and intraspecific differences in pectoral-fins spine morphology in Nile River and Lake Nasser catfishes, Siluriformes

The structure of the pectoral fins spine of 4 catfish species Heterobranchus longifilis, Clarias gariepinus, Chrysichthys auratus, Synodontis schall and Synodontis serratus were described. The fish specimens were collected from Asyut City and Lake Nasser about 319 and 900 Km south of the capital Cairo, Egypt respectively on 10 November 2017 are described. The species examined showed variation in the shape of the spine-shaft tip varies from finely to broadly and rounded pointed; the curvature of the spine-shaft is either straight or curved partially or complete; the anterior serrae varies between is either broad or irregular; the anterior ridge groove is well developed, deep, and curved, with some pores in some species; the anterior dentations varies between short and sometimes are merged together or curved and their number decreased towards the tip; the posterior dentations can vary between absent or long and numerous and sometimes increased in their number towards the tip of the spine; the dorsal, anterior and ventral processes are well developed structures, with rounded, flange-like, and the shape of the basal fossa varies in having narrow, elongated, boat-shape, with high walls at sides; and very wide fossa and lunate in shape. It is usually deep with high walls.