TWO NEW SPECIES OF STILLABOTHRIUM (CESTODA: RHINEBOTHRIIDEA) FROM STINGRAYS FROM NORTHERN AUSTRALIA AND ONE NEW COMBINATION

A study of cestode specimens that were collected during survey work on elasmobranchs collected from Taiwan and Northern Territory, Australia, revealed the presence of 1 new combination into the genus Stillabothrium (Rhinebothriidea: Escherbothriidae) and 2 new species of the genus. Phyllobothrium biacetabulatum, collected from Rhinobatos schlegelii, is transferred to Stillabo- thrium and its description is emended, as is the diagnosis for the genus Stillabothrium and the family Escherbothriidae. Stillabothrium biacetabulatum n. comb. differs from existing species of the genus in that the face of its bothridia is laced with a network of longitudinal and horizontal muscle fibers that do not contribute to the formation of septa. Stillabothrium lunae n. sp. is described from Himantura leoparda and differs from existing species of the genus in that its bothridium possesses an anterior field of 7-8 loculi that are wider than long. Stillabothrium mariae n. sp. is described from Maculabatis astra. This species differs from all species of Stillabothrium except Stillabothrium campbelli in possessing 10 12 horizontally oriented bothridial loculi. Stillabothrium mariae n. sp. differs from S. campbelli in having longer bothridia and from all other species of Stillabothrium in that it lacks, rather than possesses, conspicuous septa and loculi that are longer than wide in the posterior region of its bothridia. Bayesian and parsimony-bootstrap analysis of 28S rDNA revealed S. biacetabulatum n. comb., S. lwtae n. sp., and S. mariae n. sp. to be part of Clade 1 of Stillabothrium, with S. biacetabulatum n. comb. being the sister species to S. mariae n. sp. Stillabothrium lunae n. sp. was found to be the sister species to Stillabothrium borneoense.