Two new and one redescribed species of Acanthobothrium (Cestoda: Onchoproteocephalidea: Onchobothriidae) from Dasyatis akajei (Myliobatiformes: Dasyatidae) in the China Sea.

Acanthobothrium ningdense n. sp. and Acanthobothrium guanghaiense n. sp. are described from the spiral intestine of the whip stingray, Dasyatis akajei (Müller & Henle). Acanthobothrium ningdense n. sp. is reported based on 38 cestode specimens collected at five locations along the Chinese coast, i.e. Taizhou, Zhejiang Province, Ningde and Xiamen, Fujian Province, Taishan, Guangdong Province and Sanya, Hainan Province between 2012 and 2015. Acanthobothrium ningdense n. sp. belongs to the "species category 4" characterised by Ghoshroy & Caira. Among category 4 Acanthobothrium species, A. ningdense n. sp. most closely resembles A. micracantha Yamaguti, 1952 and A. latum Yamaguti, 1952, both from the same host species. Acanthobothrium ningdense n. sp. differs from A. micracantha by lacking a long robust hook handle that connects the bases of medial and lateral hooks, and from A. latum by having much longer axial prongs than abaxial prongs. Acanthobothrium guanghaiense n. sp., only found in Taishan, Guangdong Province in 2014, is a category 2 Acanthobothrium species. Among category 2, A. guanghaiense n. sp. most closely resembles A. semnovesiculum Verma, 1928, but can be differentiated from it by the arrangement of testes (in two staggered columns rather than in two tandem columns), and the shape of abaxial prong (nearly straight instead of with a conspicuous curve in the proximal portion). Acanthobothrium macrocephalum Wang & Yang, 2001 is redescribed based on new specimens collected from D. akajei in Guanghai and Sanya. With this study, the total number of Acanthobothrium species reported from D. akajei is brought to nine. It is possible that some of the species of Acanthobothrium previously reported from D. akajei not encountered in this study may have geographically restricted distributions, as was observed here for A. guanghaiense n. sp..