A new species of Dollfusiella Campbell & Beveridge, 1994 (Cestoda: Eutetrarhynchidae), with remarks on Halysiorhynchus macrocephalus (Shipley & Hornell, 1906) (Cestoda: Mixodigmatidae) from the bowmouth guitarfish Rhina ancylostoma Bloch & Schneider (Rhinidae) in the Persian Gulf.

Dollfusiella nimai n. sp. (Cestoda: Eutetrarhynchidae) is described from the intestine of Rhina ancylostoma Bloch & Schneider in the Persian Gulf. The number of the hooks per half spiral row in the metabasal tentacular armature distinguishes the new species from its congeners, except for D. vooremi (São Clemente & Gomes, 1989) possessing approximately the same number of hooks per half spiral row. While the principle hooks 1(1')-21(21') were homeomorphous in the metabasal armature of D. nimai n. sp., the billhooks on the antibothrial surface and the uncinate hooks on the bothrial surface were the principle hooks 1(1')-16(16') in the metabasal armature of D. vooremi. Dollfusiella nimai n. sp. most closely resembles D. michiae (Southwell, 1929) in the tentacular armature as well as the morphology of the scolex and strobila but differs clearly in the number of the hooks per half spiral row in the metabasal tentacular armature (25-26 vs 16 respectively). A detailed examination of the specimens of Halysiorhynchus macrocephalus (Shipley & Hornell, 1906) (Cestoda: Mixodigmatidae) ex R. ancylostoma from the Persian Gulf revealed intraspecific variability including the number of the principle hooks per half spiral row in the metabasal armature, the number of the hook rows in the basal armature, and the size of the basal hooks.