Ophiotaenia bungari n. sp. (Cestoda), a parasite of Bungarus fasciatus (Schneider) (Ophidia: Elapidae) from Vietnam, with comments on relative ovarian size as a new and potentially useful diagnostic character for proteocephalidean tapeworms.

Ophiotaenia bungari n. sp. (Cestoda: Proteocephalidea) is described from the intestine of the banded krait Bungarus fasciatus (Schneider) (Ophidia: Elapidae) in Vietnam. The new species differs from all but three Ophiotaenia species parasitic in Asian reptiles in the possession of a glandular apical organ. It differs from O. andersoni Jensen, Schmidt & Kuntz, 1983 in the position of the vagina in relation to the cirrus-sac (anterior and posterior in O. bungari versus anterior only in the latter species), in the cirrus-sac/proglottis width ratio (29-38 versus 50%) and by having more testes (100-150 versus 42-116 in O. andersoni); from O. chattoraji Srivastava, 1980 in the number of uterine diverticula (50-65 versus 10-26) and in the cirrus-sac/proglottis width ratio (29-38 versus 22%); and from O. rhabdophidis (Burt, 1937) by having more uterine diverticula (50-65 versus 30-45), by the cirrus-sac/proglottis width ratio (29-38 versus 20-25%) and by the width of the scolex (360-420 versus 130-187 μm). The taxonomic importance of the relative size of the ovary (i.e. the ratio of the ovarian size in relation to that of the entire proglottis), a character previously not used in the systematics of proteocephalidean cestodes, is discussed. Comparison of measurements of all of the nominal species of Ophiotaenia La Rue, 1911 and Proteocephalus Weinland, 1858 (c.135 species) has shown that the ovary of species parasitic in snakes in the Americas, Africa, Asia and Australia is not only considerably smaller than that of congeneric species from European hosts, but also smaller than in all species of Proteocephalus parasitic in teleost fishes throughout the world.