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| Imparfinis arceae Silva, Sabaj, Carvalho & Oliveira, 2025 |
Abstract
Imparfinis is a genus of small catfishes with 21 valid species broadly distributed throughout the main river basins of the Neotropical region. Here, a new species of Imparfinis is described from the headwaters of the Rio Xingu. The new species is distinguished from its congeners by the presence of a wide dark stripe from snout tip to caudal peduncle sharply contrasting pale underside and aligned with dark stripe centered on dorsal portion of lower caudal-fin lobe, 11–12 gill rakers on the first ceratobranchial, 39 vertebrae, maxillary barbel surpassing vertical through dorsal-fin origin, and absence of short, flexible extension of the anteriormost pectoral, dorsal, and upper caudal-fin rays. In addition, assemble species by automatic partitioning (ASAP) and the Poisson tree processes model (bPTP) analyses support the validity of this new species. Our molecular phylogeny based on the cytochrome c oxidase subunit 1 mitochondrial gene (COI) corroborates the placement of the new species in Imparfinis and its close relationship with I. guttatus. Species delimitation in Imparfinis is discussed.
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| Imparfinis arceae Left column: holotype, MCP 55325, 47.9 mm SL. Right column: ANSP 187252, from top to bottom: 50.5 mm SL; 43.9 mm SL; 40.6 mm SL; 36.9 mm SL. |
Imparfinis arceae, new species
Etymology.—The specific name, arceae, honors Dr. Mariangeles Arce Hernández, Executive Director of the Center for Systematic Biology and Evolution at The Academy of Natural Sciences of Drexel University, for her valuable contributions to studies of the systematics and evolution of catfishes. A genitive noun.
Gabriel de Souza da Costa e Silva, Mark Henry Sabaj, Kaylane Rodrigues de Carvalho and Claudio Oliveira. 2025. Integrative Taxonomy Reveals a New Species of Imparfinis (Siluriformes: Heptapteridae) from the Upper Xingu River Basin. Ichthyology & Herpetology. 113(1); 143-153. DOI: doi.org/10.1643/i2023097 (3 April 2025)
