Ecomorphological study of two sympatric ray species from the Southeastern Coast of Brazil: Atlanroraja cyclophora (Regan, 1903) and Rioraja agassizii (Müller & Henle, 1841) (Batoidea, Elasmobranchii)

• Grant number: 24/14640-6
• Support Opportunities: Scholarships in Brazil - Master
• Start date: May 01, 2025
• End date: May 31, 2026
• Field of knowledge: Biological Sciences - Morphology
• Principal Investigator: André Luis da Silva Casas
• Grantee: Leticia Carvalho de Oliveira
• Host Institution: Instituto do Mar (IMar). Universidade Federal de São Paulo (UNIFESP). Campus Baixada Santista. Santos , SP, Brazil

Abstract

Sharks and rays are cartilaginous fish belonging to the subclass Elasmobranchii. Rays, characterized by a dorsoventrally flattened body, belong to a monophyletic group that is divided into four orders: Rajiformes, Rhinopristiformes, Torpediniformes, and Myliobatiformes. Atlantoraja cyclophora and Rioraja agassizii are Rajiformes that live in sympatry along the Southeast coast of Brazil. This project aims to investigate the ecomorphology of these species by comparing their body and ocular structures to identify variations related to environmental selective pressures that allow their coexistence without resource competition. To achieve this, 60 specimens will be used, 30 of each species, which will undergo morphometric measurements, histological processing of the eye bulbs, and ecomorphological analyses. It is expected that morphological adaptations to the different depths inhabited by each species will be identified, contributing to the understanding of environmental conditions and their implications for sympatric coexistence. Understanding the relationship between morphology and ecology of these species is essential for their conservation. Thus, this study will provide novel data on environmental adaptations that influence the survival and ecology of these rays, aiding in the knowledge and preservation of two species classified as threatened by the IUCN.