Variação morfológica e primeiro registro de Bunocephalus hertzi (Siluriformes: Aspredinidae) na bacia do rio Dourados, alto rio Paraná, Brasil

Abstract

The order Siluriformes, which includes fishes commonly known as catfish and armored catfish, currently consists of 41 families, 512 genera, and 4,263 valid species, making it one of the most diverse groups among fish lineages. Among this group, fish belonging to the family Aspredinidae stand out due to their characteristic body shape, which resembles a banjo, earning them the popular name "banjo catfish." The most diverse genus in the family is Bunocephalus. In the upper rio Paraná basin, two species of this genus are documented: Bunocephalus hertzi and Bunocephalus larai. These species can be distinguished from their congeners by the absence of an epiphysial bar and the presence of ten principal caudal-fin rays (vs. nine). The distinction between these species is made based on the size of the coracoid process, which is larger in B. hertzi; the length of the maxillary barbels, which is greater in B. larai; and the number of bony protuberances forming the cranial ornamentation, with 4 in B. larai and 5 in B. hertzi. During the student’s Scientific Iniciation, individuals of Bunocephalus hertzi from the rio Dourados basin were identified, showing variable numbers of bony protuberances. Thus, in this study, to investigate this variation, the morphological characterization of 23 specimens of Bunocephalus deposited in the Museu da Biodiversidade (MUBIO) at the Universidade Federal da Grande Dourados (UFGD), and eight specimens deposited in the fish collection of the Museu de Zoologia da Universidade Estadual de Londrina (MZUEL) was carried out, along with a Principal Component Analysis using the data obtained. The investigation confirmed the morphological variation in cranial ornamentation in different species populations. Thus, this study represents an unprecedented record of the genus in the rio Dourados basin and describes a morphological variation of the species not yet documented in the literature.