A morphological and molecular study of adults and cystacanths of Oncicola luehei Travassos, 1917 (Acanthocephala: Archiacanthocephala), from the Neotropical region of Mexico.

Members of the genus Oncicola Travassos, 1916 are generalist parasites able to infect a broad spectrum of carnivorous hosts, such as marsupials, procyonids, felids, and canids, and are distributed globally. Adult specimens were collected from the intestines of three white-nosed coatis (N. narica), whereas cystacanths (larval form) were found in the body cavities of two amphibian species (paratenic hosts) in localities from northern and southeastern Mexico. Morphologically, both stages were identified as O. luehei (Travassos, 1917) on the basis of the following features: trunk cylindrical, narrow anteriorly, enlarging midbody, tapering gradually to narrow posteriorly; proboscis globular with six circular rows of hooks with six hooks each, decreasing in size posteriorly; neck short with sensory papilla; tubular lemnisci long, extending to the posterior region; protonephridia dendritic type; and eight cement glands, compact with a single giant nuclei. Sequences from cytochrome c oxidase subunit 1 from mtDNA were aligned and compared with sequences available in GenBank. Phylogenetic analyses revealed that adults and cystacanths formed a clade with two other isolates identified as Oncicola sp. and O. luehei from Mexico. The intraspecific genetic divergence among the isolates was low, ranging from 0.0% to 3.0%, indicating that the two stages of the life cycle belong to the same species. The haplotype network was inferred with 11 sequences and revealed a lack of shared haplotypes between populations, suggesting a reduced recombination rate and a high pattern of genetic variation among individuals. Finally, these new records of O. luehei increase the distribution range of O. luehei on both coasts of Mexico.