Scyphophyllidium uruguayense n. sp (Eucestoda : Tetraphyllidea) in Mustelus mento (Cope, 1877) (Chondrichthyes : Carcharhiniformes : Triakidae) from La Paloma, Uruguay

A new species of Scyphophyllidium inhabits Mustelus mento near La Paloma, U ruguay. It resembles Scyphophyllidium giganteum from the Atlantic Ocean and specimens identified as S. giganteum from California by having anapolytic strobilae 155-258 mm long, 250-300 craspedote proglottids, scoleces 1.2-1.4 mm wide, necks 34-41 mm long, immature and mature proglottids wider than l ong, gravid proglottids wider than long to longer than wide, genital pores averaging 28% of proglottid length from the anterior end, relatively hat ov aries with digitiform lobes reaching the lateralmost extent of the testicul ar field, vitellaria in 2 fields converging toward the proglottid midline, straight and short cirrus sacs, and postvaginal vas deferens. The bothridia of the new species have accessory bothridial suckers that are smaller than those of California specimens: European specimens reportedly lack accessor y bothridial suckers. The new species possesses a uterine, duct that joins the uterus at the level of the genital atrium and ventral osmoregulatory du cts medial rather than lateral to the dorsal ducts, an arrangement describe d for Californian but not European specimens. It differs from both European and Californian specimens by having longer cirri, more testes per proglott id, prominent scales covering the neck and vaginae and uterine ducts coiled immediately preovarially. Pithophorus, Marsupiobothrium and Scyphophyllidi um may form a clade.