Redescription of a forgotten species: Rhyacoglanis variolosus (Miranda-Riberiro 1914) (Siluriformes: Pseudopimelodidae)

• Grant number: 25/22976-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: February 01, 2026
• End date: December 31, 2026
• Field of knowledge: Biological Sciences - Zoology - Taxonomy of Recent Groups
• Principal Investigator: Claudio de Oliveira
• Grantee: Nathaly Soares Costa
• Host Institution: Instituto de Biociências (IBB). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil
• Associated research grant: 20/13433-6 - Phylogeny and molecular identification of fishes of the superorder Ostariophysi (Chordata: Actinopterygii) using genomic approaches, AP.TEM

Abstract

The genus Rhyacoglanis is characterized by light spot on the cheek, a confluence between the dark band on the caudal fin and the dark spot on the caudal peduncle, and by having 30 to 35 vertebrae The genus comprises nine valid species: R. pulcher (Boulenger, 1887), R. variolosus (Miranda-Ribeiro, 1914), R. annulatus Shibatta & Vari, 2017, R. epiblepsis Shibatta & Vari, 2017, R. paranensis Shibatta & Vari, 2017, R. rapppydanielae Shibatta, Rocha & Oliveira, 2021, R. seminiger Shibatta & Vari, 2017, R. varii Shibatta, 2023, and R. beninei Crispim-Rodrigues et al., 2023. In a recent study, a case of mass migration in the Aquidauana River, part of the Paraguay River basin, was reported as a migration event of the species R. paranensis, due to the lack of a clear diagnosis distinguishing the species occurring in the Paraná-Paraguay system. However, considering the locality, it is likely to be R. variolosus, highlighting the need for a detailed redescription of R. variolosus, including its diagnosis in relation to its congeners. Therefore, for the present study, morphological and molecular analyses will be conducted with the primary objective of producing a redescription of R. variolosus and a detailed comparison between this species and R. paranensis, thereby contributing to a better understanding of the biodiversity of species within the genus that occur in the Paraná-Paraguay system. (AU)