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Larval trematodes infecting the snail Heleobia australis (Cochliopidae) from the Bahía Blanca estuary, Argentina were surveyed for two years. A total of 7,504 snail specimens was dissected and the larval stages of 15 different trematodes were recovered and examined morphologically. These larvae included four species that had previously been reported from H. australis in Brazil, Uruguay, and Argentina: the heterophyid Ascocotyle (Phagicola) longa and the microphallids, Maritrema bonaerense, Maritrema orensense, and Microphallus simillimus. Three other species, the echinostomatid Stephanoprora uruguayensis, the microphallid Levinseniella cruzi, and the psilostomid Psilochasmus oxyurus are reported here for the first time as parasites of H. australis. Eight other trematodes found in H. australis are described and placed in the appropriate superfamilies, families or genera (Cryptogonimidae, Apocreadiidae, Aporocotylidae, Notocotylidae, Haploporidae, Renicolidae, Himasthla, and Renicola). The prevalence of the trematode taxa infecting H. australis in the Bahía Blanca estuary was low (<3%) with a single exception (M. simillimus; >20%). Microphallidae were the richest and the most prevalent family, probably because of the high abundance of crabs — the second-intermediate hosts of certain microphallid species — and the considerable diversity of gulls. Here we compare the parasite assemblage found in the H. australis from Bahía Blanca estuary with other parasite assemblages infecting Heleobia spp. and other rissooids from the rest of the world.
Demidospermus annulus sp. nov. (Platyhelminthes, Monogenea, Ancyrocephalidae) is described from the gills of the catfish Parapimelodus valenciennis Lütken collected in Samborombón Bay, Argentina. The new species differs from all congeneric species mainly by the structure of the accessory piece of the male copulatory organ, the sclerotized ring-shaped vaginal aperture and the dorsal bar articulation.
Stephanoprora podicipei sp. n. parasite of great grebe Podiceps major Boddaert, 1785 (Aves, Podicipedidae) from Mar Chiquita coastal lagoon (Buenos Aires, Argentina) is described and illustrated. The new species presents common features with S. conciliata Dietz, 1909; S. manei Holcman-Spector et Olagüe, 1986; S. dogieli Holcman-Spector et Olagüe, 1989 and S. uruguayense Holcman-Spector et Olagüe, 1989. S. podicipei sp. n. can be clearly distinguished from these species, principally, by the smaller size of its body, peristomic disk, testes, ovary and by its shorter oesophagus and uterus. S. podicipei also differs from S. argentiniensis Sutton et al., 1982, the other species of this genus parasitizing Podiceps major in Argentina, in the number of spines of the peristomic disk (22 vs. 20), in its smaller body, peristomic disk and testes; in its larger acetabulum and eggs, in the shape of the testes and in its vitellaria extending to the middle of the anterior testis.
A new metacercaria (Digenea, Gymnophallidae) parasite of limpets Nacella (P.) magellanica and N. (P.) deaurata from Isla Conejo Beagle Channel (Tierra del Fuego, Argentina) is described and illustrated. According to the evaluation of characters of the family Gymnophallidae proposed by Ching (1995) the metacercariae can be included in the genus Lacunovermis Ching, 1965. The presence of a ventral pit, a wide genital pore, lateral papillae of oral sucker and broad, multipointed spines within tegumental pits confirm this inclusion. The new metacercariae differ in every measurement and ratios of L. macomae (the only valid species for the genus). The metacercaria show high prevalence (40 to 100%) and overdispersed distribution. This is the first record of the genus Lacunovermis for the Subantarctic waters.
Background. Monogenean parasites from mixohaline areas of the South Atlantic coast of Argentina are very poorly reported. The aim of this paper is report a new host and locality for Absonifibula bychowskyi, a monogenean confined to fish living in estuarine areas. Some ecological considerations about the host-parasite relationship are also discussed. Materials and Methods. Parasites collected from whitemouth croaker, Micropogonias furnieri (Desmarest, 1823) (Actinopterygii: Sciaenidae), were studied from fixed- and live specimens, with standard procedures used in parasitology. Prevalence, mean intensity, and abundance of parasites were calculated and related to the host body size. Spearman′s rank correlation coefficient was calculated to determine possible correlations between host length, parasite intensity, and prevalence. Results. Absonifibula bychowskyi (Monogenea: Diclidophoridae) Lawler et Overstreet, 1976 is reported for the first time from the gills of whitemouth croaker, at the Samborombón Bay, a mixohaline area in the Buenos Aires Province, Southwest Atlantic Ocean. The parasite was found only in juveniles of M. furnieri that use the Samborombón Bay as the main estuarine nursery ground area. When the croaker migrated seawards, A. bychowskyi disappeared from the gills may be related to the increased salinity. Conclusion. This is the first record for Absonifibula bychowskyi in the Southwest Atlantic and M. furnieri. (It constitutes a new host record.) The presence of A. bychowskyi in M. furnieri could be indicative of the origin of the fish.
Seriolella porosa (Silver warehou) is an important fish resource in the Argentine Sea. No previous studies have been carried out to date on its parasite fauna. The present study aims to (i) identify the digenean trematodes that parasitize Silver warehou, (ii) estimate parasite frequency and abundance, and (iii) establish their relationship with fish size and sex. A total of 100 specimens of S. porosa from San Matías Gulf, Argentina were examined between September and October 2006. Host size and sex were determined. Parasites extracted from the stomach lumen were fixed, conserved in 5% formalin, and stained with Langeron’s hydrochloric carmine. The following parameters were also determined: dispersion coefficient, prevalence, intensity, and parasite abundance. Differences in parasitism were assessed using non-parametric tests. Four adult digenean species were found in the stomach, namely Lecithocladium cristatum, Aponurus laguncula, Elytrophalloides oatesi and Gonocerca cf. phycidis. L. cristatum was not only dominant but also the most prevalent and abundant species. None of the digeneans showed interspecific association with each other and therefore they might follow different patterns of colonization (i.e., different intermediate hosts, seasonal and/or spatial distribution of the infective stages). Significant differences were observed among the digeneans analyzed in respect to the sex of the host. Results from this study show that Silver warehou plays a key role as a final host of a significant number of digeneans in the ecosystem. This study is the first step in an attempt to further determine the larval stages in intermediate hosts in San Matías Gulf.
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