Osteology and sexual dimorphism of Hyspsolebias janaubensis (Cyprinodontiformes: Rivulidae), an endemic specie of annual fish critically threatened with extinction

• Grant number: 24/12969-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: November 01, 2024
• End date: October 31, 2025
• Field of knowledge: Biological Sciences - Morphology - Anatomy
• Principal Investigator: Pedro Pereira Rizzato
• Grantee: André de Paula Madeira
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Hypsolebias janaubensis (Costa, 2006), popularly known as the Cloud Fish of Janaúba, is an annual killifish species (Cyprinodontiformes: Rivulidae) which, similar to many other species in that group, is threatened with extinction, being currently classified as Critically Endangered (CR). Despite evoking great interest due to their specialized life cycles, morphological studies on these fishes remain scarce, and the internal anatomy of several rivulid species is unknown. Such is the case of H. janaubensis. Its taxonomic description focused on external morphological features, and its internal anatomy, including osteology, is mostly unknown. There is no information, for example, whether sexually dimorphic characteristics are present in its skeleton. In this project, we aim to study, describe and illustrate the skeleton of H. janaubensis, and to investigate its sexual dimorphism. In order to achieve these goals, traditional (e.g. clearing and staining methods) and modern (computerized microtomography, or µCT) techniques of bony fish morphological investigation will be applied in an integrative approach. Six specimens of H. janaubensis (three males and three females) are already available in the laboratory where the study will be developed, as well as µCT data of those six specimens, which are unprecedented for this species. The study and its results will be contextualized in the PAN Rivulídeos, an action plan for the conservation of these threatened fishes.