Review of the genus Eutetrarhynchus Pintner, 1913 (Trypanorhyncha: Eutetrarhynchidae), with the description of Eutetrarhynchus beveridgei n. sp.

The genus Eutetrarhynchus Pintner, 1913 is revised. Eutetrarhynchus beveridgei n. sp. is described from the spiral intestine of the dwarf whipray, Himantura walga (Müller & Henle) (Myliobatiformes: Dasyatidae), from the South China Sea off the Malaysian part of Borneo. The new species is characterised by a slender, elongate scolex, two oval bothria, muscular bulbs, retractor muscles inserting at the base of the bulbs, and the presence of gland-cells and prebulbar organs. The tentacular armature is typical heteroacanthous with heteromorphous hooks. Eutetrarhynchus beveridgei n. sp. is allocated to the genus due to its distinct segment morphology featuring two internal seminal vesicles and scattered testes occupying the complete intervascular space. It differs from congeners in its relatively small size, much smaller scolex regions and in the presence of a basal armature with a distinct basal swelling. Eutetrarhynchus cortezensis Friggens & Duszynski, 2005 is transferred to Dollfusiella Campbell & Beveridge, 1994, as D. cortezensis n. comb., on the basis of its segment morphology, with testes in a linear arrangement and the absence of internal seminal vesicles. A new generic diagnosis and a key for the identification of species of Eutetrarhynchus is provided.