Additional description and molecular characterization of Naobranchia lizae (Krøyer, 1863) and Naobranchia variabilis Brian, 1924 (Copepoda: Lernaeopodidae) from the Mexican Pacific

Abstract Members of the copepod family Lernaeopodidae are parasites of chondrichthyan and actinopterygian fishes, with the genus Naobranchia Hesse, 1863 being one of the most diverse groups parasitizing the gills of marine fishes. The genus currently comprises 21 species; however, molecular data for most species remain unavailable or poorly validated. In this study, copepod specimens were collected from the gills of Mugil cephalus Linnaeus, 1758 in Teacapán, Sinaloa, and from Aluterus monoceros Linnaeus, 1758 in Puerto Ángel, Oaxaca, along the Mexican coast of the eastern tropical Pacific. Based on morphological examination, these specimens were identified as Naobranchia lizae (Krøyer, 1863) and Naobranchia variabilis Brian, 1924, respectively. Morphological features of both species were documented through detailed drawings and photographs. In addition, a fragment of the mitochondrial cytochrome c oxidase subunit I ( cox 1) and two nuclear ribosomal DNA markers (18S and 28S) were generated for both taxa, representing the first well-documented molecular data for the genus Naobranchia . Phylogenetic analysis of cox 1 placed N . lizae and N . variabilis in the same clade with an unpublished sequence of Naobranchia vermiformis Rangnekar, 1956 (ON023684), forming a well-supported monophyletic group. The genetic distances between species of Naobranchia range from 13 to 19%, consistent with interspecific levels reported for other lernaeopodids. Our findings provide evidence supporting the presence of N . lizae and N . variabilis in the Mexican Pacific, establishing a reliable morphological and molecular reference to support future ecological, biogeographical, and systematic studies of Lernaeopodidae.