Two new species of Acanthobothrium Blanchard, 1848 (Onchobothriidae) in Narcineentemedor Jordan & Starks, 1895 (Narcinidae) from Acapulco, Guerrero, Mexico.

Two species of Acanthobothrium (Onchoproteocephalidea: Onchobothriidae) are described from the spiral intestine of Narcineentemedor Jordan & Starks, 1895, in Bahía de Acapulco, Acapulco, Guerrero, Mexico. Based on the four criteria used for the identification of species of Acanthobothrium, A.soniae sp. nov. is a Category 2 species (less than 15 mm in total length with less than 50 proglottids, less than 80 testes, and with the ovary asymmetrical in shape). Acanthobothriumvidali sp. nov. is a Category 6 species (more than 15 mm in total length with more than 50 proglottids, fewer than 80 testes, and the ovary is asymmetrical). The new species differ from similar species from the Pacific Ocean by total length, the number of proglottids, diameter of the accessory sucker, the length of the cirrus sac, the number of testes per proglottid and the measurements of hooks. With the recognition of A.soniae sp. nov. and A.vidali sp. nov., 42 species of Acanthobothrium have been reported from the Pacific coast of the Americas. This is the first report of species of Acanthobothrium from a member of Narcine from Mexico and it brings the number of species reported from elasmobranchs from the Pacific Coast of Mexico to 13.