During a parasitological survey of teleosts and elasmobranchs in the Argentine Sea, 3 species of eutetrarhynchids were collected from the batoids Myliobatis goodei Garman and Psammobatis bergi Marini, and the shark Mustelus schmitti Springer. The specimens collected from Mu. schmitti were identified as Dollfusiela vooremi (São Clemente et Gomes, 1989), whereas the specimens from My. goodei and Ps. bergi resulted in new species of Dollfusiella Campbell et Beveridge, 1994 and Parachristianella Dollfus, 1946, respectively. Dollfusiella taminii sp. n. from Ps. bergi is characterised by a distinct basal armature with basal swelling and a heteroacanthous homeomorphous metabasal armature with 7-9 falcate hooks per principal row. Parachristianella damiani sp. n. from My. goodei lacks a distinct basal armature, having 2-3 initial rows of uncinate hooks, a heteroacanthous heteromorphous metabasal armature with the first principal row of small hooks, followed by rows with 10-14 large hooks. This is the first record of Parachristianella in the southwestern Atlantic. The amended description of D. vooremi includes the detailed description of the tentacular armature, including SEM micrographs of all tentacular surfaces. This species is characterised by a basal armature consisting of rows of uncinate and falcate hooks, a basal swelling and a metabasal armature with billhooks on the antibothrial surface and uncinate hooks on the bothrial surface. The scolex peduncle of D. vooremi is covered with enlarged spinitriches. This species is restricted to carcharhiniform sharks, since the report of D. vooremi in Sympterygia bonapartii Müller et Henle off Bahía Blanca (Argentina) is dubious.
The parasitic copepod fauna of 182 specimens of Mustelus schmitti Springer from the coast of Mar del Plata, Argentina was investigated. Three species of parasitic copepods were identified: Nessipus orientalis Heller, 1865 from the buccal cavity, Perissopus oblongus (Wilson, 1908) from the edge of pectoral, pelvic, dorsal, anal and caudal fins and in claspers, and Lernaeopoda galei К rayer, 1837 from the base of the pectoral fins. N. orientalis was most common being present the entire year, while P. oblongus and L. galei occurred seasonally with low prevalence and mean intensity. There were differences in the site of infection by these copepods and variations in the relationship between prevalence and mean intensity and host size and seasonality. These parameters were unrelated to host sex. Our data suggest that the structure of this parasite community is a result of a complex of biotic and abiotic factors, such as temperature, spawning and breeding preferences of the host, and overlapping in the distribution of different shark species. This is the first report of N. orientalis in Argentinean waters.