Two new species of Acanthobothrium Blanchard, 1848 (Cestoda: Onchoproteocephalidea) from rajiform batoids off Argentina.

Two new species of Acanthobothrium Blanchard, 1848 were collected from rajiform batoids along the coast of Argentina. They are Acanthobothrium carolinae sp. n. from Bathyraja magellanica (Philippi) and Acanthobothrium domingae sp. n. from Dipturus brevicaudatus (Marini). Both belong to category 1 and 2 because their total length is lower than 15 mm, they have fewer than 50 proglottids, fewer than 80 testes and a symmetric or asymmetric ovary. Acanthobothrium carolinae sp. n. differs from all congeners by the following combination of features: proglottid apolysis, hook morphology, microthrix pattern on the cephalic peduncle and distribution of the vitelline follicles. Acanthobothrium domingae sp. n. is unique in the combination of proglottid apolysis, total length, number of proglottids, hook and septal morphology, microthrix pattern on the cephalic peduncle, number and distribution of testes, cirrus sac length, distribution of the vitelline follicles and genital pore position. The discovery of these species increases the number of species of Acanthobothrium parasitising rajiform batoids off Argentina from one to three. All three species have a unique pattern of distribution of the gladiate spinitriches along the length of the cephalic peduncle, i.e., gladiate spinitriches being interrupted in a medial line both dorsally and ventrally.