Desenvolvimento ontogenético do espinho da nadadeira peitoral de Calophysus macropterus Muller & Troschel 1843 (Pimelodidae-Siluriformes)

Abstract

The pectoral fin spines of Siluriformes have a wide morphological variation, with great importance in the taxonomy of many groups. The characteristic and morphologically variable pectoral fin spine of catfish (order Siluriformes) has been well investigated based on later developmental stages (juvenile and adult), but information on early life stages is lacking. Thus, through morphological and osteological analyses, this research aimed to study the anatomy of the pectoral fin spine of Calophysus macropterus (Siluriformes, Pimelodidae), popularly known as piracatinga, throughout the ontogeny of the species. Calophysus macropterus is the only valid species for the genus, so it is necessary to study the ontogenetic characteristics of the development of the pectoral spine to understand the current species and for future studies on the taxonomy of the group. The morphological analyses revealed that there is no variation in the spines of adult specimens; all of them presented the basic structures of the Siluriformes spine, both in the spine and in the ornamentations. Analyzing juvenile specimens revealed variations in the first stages of life, with spines without any type of ornamentation, others having both serras and dentitions and others only serras. These morphological variations may contribute to the study of the species while collaborating with the existing literature on the study of the pectoral fin throughout the ontogeny of Calophysus macropterus. We encourage the continuity of morphological studies of the pectoral-fin spine, including new characters. Keywords: Piracatinga; Spine; Ontogeny; Silurus.