Morphometric and molecular differentiation of Pimelodus grosskopfii and Pimelodus yuma (Siluriformes: Pimelodidae)

Abstract

Pimelodus grosskopfii and Pimelodus yuma, two species endemic to the Magdalena-Cauca basin in Colombia, overlap in the ranges of some of their diagnostic characters, which hampers their correct morphological identification. Aiming to help discriminate these species, this study conducted an integrative analysis using traditional and geometric morphometrics, phylogenetic analysis based on partial sequences of the mitochondrial cytochrome c oxidase subunit 1 gene (COI, cox1) and the identification of diagnostic Single Nucleotide Polymorphism markers (SNP). The species differ significantly in body geometry, allowing 100% discrimination, which was reinforced by a phylogenetic analysis that recovered well-supported monophyly of each species (posterior probability > 0.95). Additionally, the traditional morphometric results corroborated some previously reported diagnostic traits for both species and let us describe one non-overlapping ratio related to the adipose fin length. Three of five SNP markers had reciprocally exclusive alleles suitable for identifying each species. The morphometric and molecular methods conducted in this study constitute alternative tools for the correct discrimination of P. grosskopfii and P. yuma in the wild and in captive populations used for aquaculture.

Phylogenomics of the catfish family Pimelodidae with focus on the genus Pimelodus support the recognition of Sorubiminae and Pimelodinae (Teleostei, Siluriformes)

“…These two species distinctively share an unusually long adipose fin that is contained less than 4.35 times in SL (Villa-Navarro et al, 2017). Based on our results and those of Lundberg et al (2011) andJoya et al (2023), Pimelodus grosskopfii and P. crypticus are not true members of the genus Pimelodus and instead represent a trans-Andean endemic lineage sister to a speciose group composed of the Pimelodus maculatus (southeastern SA) and Pimelodus blochii (widespread) sister clades.…”

“…Pimelodus grosskopfii (Figure 2j) is a trans-Andean species distributed in the Magdalena, Cauca, and San Jorge basins (Villa-Navarro et al, 2017). A recent study using mitochondrial and nuclear data of Pimelodus from the Magdalena-Cauca basin recovered a close relationship between P. grosskopfii and P. crypticus (Joya et al, 2023), the latter described from the upper Cauca by Villa-Navarro et al (2017). These two species distinctively share an unusually long adipose fin that is contained less than 4.35 times in SL (Villa-Navarro et al, 2017).…”