Review of the Chihuahua Catfish (Ictalurus sp. 1)

The Chihuahua Catfish (Ictalurus sp. 1) is a putative species that has never been formally described in peer-reviewed literature as a valid taxonomic entity. A 1998 draft species description was never completed (Humphries and Miller 1998, entire; Hendrickson 2017, p. 3). The Chihuahua Catfish is morphologically similar to or indistinguishable from the Headwater (I. lupus) Catfish with which it would hypothetically be sympatric (Humphries and Miller 1998, pp. 4, 8). Most quantitative values for comparative morphological traits overlap for the Chihuahua and Headwater Catfishes (I. lupus) [Humphries and Miller 1998, p. 19]. Extensive surveys in New Mexico and Texas did not produce any evidence that the Chihuahua Catfish exists in either state (McClure-Baker et al. 2010, pp. 1,781-1,784; Parker et al. 2021, pp. 535-537, 539, 545). Genetic analyses have found no evidence for existence of a genetically distinct population in the United States or Mexico that would correspond with the purported range of the Chihuahua Catfish (McClure-Baker et al. 2010, pp. 1,781-1,784; Parker et al. 2021, pp. 535-537, 539, 545; Bean et al. 2022; Pérez-Rodríquez et al. 2022, pp. 15-20, 22, 32-35). A recent study did identify genetically differentiated populations of Ictalurus species (e.g., Headwater and Yaqui Catfishes [I. pricei]) that may represent undescribed species (Pérez-Rodríguez et al. 2022, pp. 7-22, 32-35). However, none of these populations were described as Chihuahua catfish (Pérez-Rodríguez et al. 2022, pp. 19-20, 32-33). To date, no peer-reviewed publications have directly addressed the taxonomic status of the Chihuahua Catfish or provided evidence of its existence as a distinct species. We have reviewed all the available information regarding the taxonomic status of the putative Chihuahua Catfish and conclude that there is insufficient credible scientific evidence that the entity qualifies as a valid species or subspecies.