Desenvolvimento osteológico de Pseudacanthicus pirarara (Siluriformes, Loricariidae)

Abstract

The Loricariidae family is characterized by encompassing a great diversity of species, many of which are present in the Amazon basin. Pseudacanthicus pirarara is a large- sized catfish species that has records of occurrence in the Xingu river basin. The species has an intense orange or almost red color on its fins, in addition to rows of yellow covered by dermal bone plates formed by highly developed odontodes, these are characteristics that make P. pirarara a prominent species in the aquarium trade, in which has long attracted the attention of aquarists around the world. One of the most studied anatomical systems in fish is the skeleton, so that the characteristics present in the bones of individuals are essential for directing work on the description and morphology of species. Studies that investigate the osteological development of fish can be carried out with individuals in different periods of life, however, works that use specimens in the initial stages of development are more detailed, presenting exclusive data, in addition to serving as comparison material for other Teleosts. Thus, the main objective of this study is to carry out a complete osteological description of the representatives of Pseudacanthicus pirarara that are in the initial stages of life, in addition to reporting the osteological development of the individuals during the larval period. The specimens used for this study come from ex situ reproduction procedures realized at the Laboratório de Aquicultura de Peixes Ornamentais do Xingu (LAQUAX). One hundred individuals were obtained in different stages of life and degrees of development. For the osteological analyses, the individuals were submmited to the Taylor & Van Dyke diaphanization protocol with adaptations for larvae. Subsequently, osteological analyzes were carried out through the dissection of the specimens, so that a complete elaboration of the nomenclature of the bone structures was possible. During the analyses, we investigated the moment of ossification of the structures, considering the life stages and the standard length of the individuals, seeking to record the initial ontogenetic development, and to elaborate the first osteological description of a large Loricariidae species. Finally, we discuss the heterochronies and the moment of ossification of the bone complexes in P. pirarara, comparing with the available ontogenetic data of another representative of Loricariidae, and of two other Siluriformes.