A study on morphological convergence between Lophiosilurus alexandri Steindachner, 1876 (Pseudopimelodidae, Siluriformes) and species of the genus Chaca Gray, 1831 (Chacidae, Siluriformes).

• Grant number: 23/09873-9
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: December 01, 2023
• End date: April 03, 2025
• Field of knowledge: Biological Sciences - Zoology - Morphology of Recent Groups
• Principal Investigator: Pedro Pereira Rizzato
• Grantee: Isadora Finamor de Souza
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated scholarship(s): 24/03805-4 - Computed Tomography (CT) as an additional, non-invasive tool for studying the osteology of Lophiosilurus alexandri (Siluriformes: Pseudopimelodidae), BE.EP.IC

Abstract

Evolutionary convergence is a recurring phenomenon in several groups of organisms in which two or more species share characters that were not present in their common ancestor. This project aims to study an extreme example of this phenomenon in the group of bony fishes popularly known as catfishes (Teleostei: Siluriformes), which includes an amazingly diverse variety of species and shapes. An extreme morphological convergence exists in this group between species that are phylogenetically and geographically distant: Lophiosilurus alexandri Steindachner 1876, the "pacamã", a member of Pseudopimelodidae endemic to the São Francisco River, and species from the genus Chaca Grey, 1831 that live in Southeast Asia. The main goal of the project is to provide a detailed osteological description of L. alexandri and compare their general morphology and osteology with the ones in the species from the Asian genus. Traditional techniques of morphological studies will be used combined with modern methodologies and technologies of anatomical investigation, including computed tomography (CT-scan). As part of the project, The Academy of Natural Sciences of Drexel University (ANSP) will be visited aiming to learn and improve the use of softwares to analyse CT-scan data, besides complementing the taxon sampling for the analyses. The hypothesis to be tested is that the characteristics shared by Lophiosilurus alexandri and Chaca spp. originated separately in association with their life habits.