Urotrygon

Abstract: Cestodes collected in spiral valves of the stingray Urotrygon chilensis from the Pacific coast of Costa Rica represent an undescribed species of Tetraphyllidea. By possessing more than 2 loculi as well as an apical sucker on each bothridium, the new species is diagnosably distinct from all other tetraphyllidean genera; therefore, a new genus is proposed for it. The new species also possesses globular structures irregularly arranged on the surface of the bothridia. We found similar structures on the bothridial faces of Trilocularia acanthiaevulgaris, possibly indicating phylogenetic relationships with the new species. This possibility is enhanced by the observation that the bothridia of T. acanthiaevulgaris comprise 2 loculi and an apical sucker, rather than 3 loculi.

Abstract: Parachristianella parva sp. nov. is described from the spiral valve of Urobatis maculatus Garman, 1913 from the Gulf of California, Mexico. The new species is distinguished by its small size and small number of testes per segment (8–10). Parachristianella trygonis Dollfus, 1946 is reported from the spiral valve of Mobula munkiana Notarbartolo di Sciari, 1987 and from Dasyatis brevis (Garman, 1880), whereas the adult of Parachristianella dimegacantha Kruse, 1959 is described for the first time from the spiral valves of Urotrygon simulatrix Miyake and McEachran, 1988; Sphyrna zygaena (Linnaeus, 1758); and Dasyatis longus (Garman, 1880), all from the Gulf of California.

Abstract: From October 1997 to April, 1998 seventy-nine specimens of the ray Urotrygon microphthalmum were captured, all of them showing sexual dimorphism. They were processed in order to study their morphometrics, feeding habits, and reproduction. The largest was 300 mm in total length and the smallest one 64.4 mm, weighing 103.4 g and 12.5 g respectively. They fed mainly on crustaceans and ploychaeta; of the stomach contents 94.5 % were shrimp and 5.49% polychaeta. 7.6% of the total had empty stomachs. As far as reproduction, three sexual stages were found: 51% juvenile, 30% adult and 19% pregnant, with an average of three embryos per uterus. Among the male fishes analysed 84.4% were juvenile and 16.6% adults.