Myxosporeans and coccidians parasitic on engraulid fishes from the coasts of Argentina and Uruguay

Two new species of the genus Sphaeromyxa (Myxosporea) from the gall bladder and one new species of the genus Eimeria (Coccidia) parasitizing the testes, are reported from engraulid fishes from the Argentinian shelf (including the Argentinean- Uruguayan Common Fishing Zone): Sphaeromyxa bonaerensis n. sp., found in Engraulis anchoita Hubbs & Marini, 1935 (argentine anchovy) (prevalence 0.2 %) and in Anchoa marini Hildebrand, 1943 (anchovy) (prevalence 24.2%) caught in the Bonaerense region of the Argentinian Sea; Sphaeromyxa argentinensis n. sp. found in E. anchoita from all the sampled localities between 34° S and 46° S (prevalence 26.8 %) and from A. marini at Mar del Plata coastal zone (prevalence 1.01 %). Eimeria patagonensis n. sp. was found in E. anchoita living in the Patagonian region of the Argentine Sea (prevalence 0.45 %). Details of some ultrastructural features of S. argentinensis are provided

Graphidioides subterraneus n. sp. (Nematoda: Trichostrongyloidea) from the South American subterranean rodent Ctenomys talarum Thomas, 1898 (Rodentia: Octodontidae)

A new nematode species, Graphidioides subterraneus n. sp., found in the stomach of C. talarum from Argentina is described. The new species more closely resembles G. mazzai Lent & Freitas, 1935, parasite of Galea leucoblephara from Argentina, and G. kravetzi Sutton & Durette-Desset, 1995, parasite of Holochilus brasiliensis from Uruguay. It can be distinguished by shorter spicules, by the shape of the gubernaculum, by shorter uterine branches, and by a different number of ridges of the synlophe all along the body

n. sp. (Nematoda: Trichostrongyloidea) from the South American subterranean rodent

A new nematode species, Graphidioides subterraneus n. sp., found in the stomach of C. talarum from Argentina is described. The new species more closely resembles G. mazzai Lent & Freitas, 1935, parasite of Galea leucoblephara from Argentina, and G. kravetzi Sutton & Durette-Desset, 1995, parasite of Holochilus brasiliensis from Uruguay. It can be distinguished by shorter spicules, by the shape of the gubernaculum, by shorter uterine branches, and by a different number of ridges of the synlophe all along the body

A new species of

Cucullanus genypteri sp. n, a parasite of Genypterus blacodes Schneider, 1801 and G. brasiliensis Reagan, 1903 (Pisces: Ophidiidae) from different zones of the South West Atlantic Ocean is described and illustrated. The new species is distinguished from other south american members in the genus Cucullanus Mueller, 1777 by the distribution pattern of caudal papillae and by the body measurements, particularly spicule length. C. genypteri represents the first description of a marine species of this genus from Argentina. Variations of parasitism in relation to host size, sex and geographic distribution are also discussed

Larvae and adults of

Hysterothylacium aduncum (Rudolphi, 1802) is reported from five fishes and one invertebrate species. Third-stage larvae were found in the crustacean Themisto gaudichaudii and in mesenteries of the fishes Engraulis anchoita and Merluccius hubbsi ; fourth-stage larvae were recovered from the digestive tract of M. hubbsi and Scomber japonicus and adult specimens were obtained from the stomach and intestine of M. hubbsi, S. japonicus, Genypterus blacodes and Genypterus brasiliensis. Nematodes are described, measured and illustrated. Parasitic prevalence, mean intensity and range were calculated in relation to different geographic zones, from the Argentinean-Uruguayan Common Fishing Zone to Patagonic areas. An increase of parasitism from the northern areas southwards was observed. The life-cycle of H. aduncum, involving the host species considered, is also postulated

Genetic relationships among species of Contracaecum Railliet & Henry, 1912 and Phocascaris Höst, 1932 (Nematoda: Anisakidae) from pinnipeds inferred from mitochondrial cox2 sequences, and congruence with allozyme data

The genetic relationships among 11 taxa, belonging to the genus Contracaecum (C. osculatum A, C. osculatum B, C. osculatum (s.s.), C. osculatum D, C. osculatum E, C. osculatum baicalensis, C. mirounga, C. radiatum, C. ogmorhini (s.s.), C. margolisi) and Phocascaris (Phocascaris cystophorae), parasites as adults of seals, were inferred from sequence analysis (519 bp) of the mitochondrial cytochrome c oxidase subunit II (mtDNA cox2) gene. Phylogenetic analyses obtained from Parsimony (MP) and Neighbour-Joining (NJ) K2P distance values generated similar topologies, each well supported at major nodes. All analyses delineated two main clades: the first encompassing the parasites of the phocid seals, i.e. the C. osculatum species complex, C. osculatum baicalensis, C. mirounga and C. radiatum, with the latter two species forming a separate subclade; the second including the parasites of otarids, i.e. C. ogmorhini (s.s.) and C. margolisi. An overall high congruence between mtDNA inferred tree topologies and those produced from nuclear data sets (20 allozyme loci) was observed. Comparison of the phylogenetic hypothesis here produced for Contracaecum spp. plus Phocascaris with those currently available for their definitive hosts (pinnipeds) suggests parallelism between hosts and parasite phylogenetic tree topologies