Osteology-focused revision of the Hyphessobrycon pulchripinnis species-complex and its relatives using high-resolution X-ray computed tomography

• Grant number: 23/16223-0
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: December 10, 2024
• End date: December 09, 2025
• Field of knowledge: Biological Sciences - Zoology - Taxonomy of Recent Groups
• Principal Investigator: Claudio de Oliveira
• Grantee: Tiago de Carvalho Faria
• Supervisor: Nathan Keller Lujan
• Host Institution: Instituto de Biociências (IBB). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil
• Institution abroad: Royal Ontario Museum (ROM), Canada
• Associated to the scholarship: 21/00242-0 - Systematics and phylogeography of the tetras of the Hyphessobrycon pulchripinnis species-complex (Characiformes: Characidae), BP.DR

Abstract

With 171 currently valid species distributed throughout the Neotropical region, the genus Hyphessobrycon is the most species-rich genus in the order Characiformes. Recently placed in the subfamily Stethaprioninae, Hyphessobrycon is considered non-monophyletic. Morphological characters that define the genus, such as an incompletely-pored lateral line, unscaled caudal fin, and premaxilla with two tooth rows, inner row possessing five or more teeth, have been historically considered to be convergent and related to reductions in body size. Due to their non-monophyly, the systematics of Hyphessobrycon and related taxa have been difficult to access using morphological data. Various authors have proposed possible natural groups within Hyphessobrycon as the Hyphessobrycon agulha species-group, Hy. heterorhabdus species-group, and the Rosy Tetra clade. In this project I will visit major ichthyological collections in Canada and the United States of America to identify Hyphessobrycon specimens having a color pattern matching the Hy. pulchripinnis species-complex: two humeral blotches, the second blotch very diffuse, black stripe on the ventralmost caudal peduncle immediately posterior to anal-fin terminus, and relatively tall body and caudal peduncle. The main objectives of the project are twofold: (1) to visit those ichthyological collections having the largest holdings of specimens from northernmost South America, since most collected material is in North American collections; and (2) to use high resolution X-ray CT technology to obtain detailed 3D images of the internal skeletal anatomy of the Hyphessobrycon pulchripinnis species-complex, such as the cranium, paired-fin girdles, and hypural complex, to facilitate morphological comparisons of type and non-type specimens of all ingroup species and close outgroups such as Makunaima and Moenkhausia pittieri. This project will provide a comprehensive systematic revision and well-illustrated guide to the taxonomic characters, evolutionary relationships, and morphological diversity of the Hyphessobrycon pulchripinnis species-complex and related taxa, thus allowing me to test the hypothesis that color pattern provides a reliable means of inferring evolutionary history in this group.