A new species of Acanthocephala is described based on specimens found parasitising the intestine of the gafftopsail pompano Trachinotus rhodopus Gill in the State of Oaxaca, off the Pacific coast of Mexico. Rhadinorhynchus villalobosi sp. n. differs from the other 25 species of the genus known from the Pacific Ocean by a combination of morphological traits, such as the fewer number of rows of hooks along the proboscis, the distribution of spines of the trunk forming two fields, the position of genital pore, subterminal in both sexes, a shorter neck and cement glands, among others. The phylogenetic analyses based on sequences of the nuclear 18S and 28S rRNA genes, as well as the mitochondrial cox1, all agree that R. villalobosi sp. n. is part of the genus, and closely related to Rhadinorhynchus trachinoti Grano-Maldonado, Sereno-Uribe, Hernández-Payán, Pérez-Ponce de León et García-Varela, 2025, a recently described Mexican species, despite the marked morphological differences between the two and being distributed in different areas.

Especializacion en Microscopia Electronica en Ciencias Biologicas Posgrado en Ciencias Biologicas Facultad de Ciencias Universidad Nacional Autonoma de Mexico Mexico City Mexico

Laboratorio de Helmintologia Departamento de Zoologia Instituto de Biologia Universidad Nacional Autonoma de Mexico Mexico City Mexico *Address for correspondence Alejandro Oceguera Figueroa Laboratorio de Helmintologia Departamento de Zoologia Instituto de Biologia Universidad Nacional Autonoma de Mexico Ciudad de Mexico Mexico Avenida Universidad 3000 Ciudad Universitaria Coyoacan C P 04510 Mexico City Mexico E mail

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