A New Species of Cryptocotyle (Digenea: Heterophyidae) Infecting Kelp Gull and a Galaxiid Fish in Patagonian Freshwater Environments: Morphological and Molecular Analyses.

Adults of a species of Cryptocotyle were found infecting the intestine of the kelp gull, Larus dominicanus Lichtenstein, 1823, and metacercariae were found in the fins and muscle of the galaxiid fish, Galaxias platei Steindachner, 1898 (local name "puyen grande"), in Nahuel Huapi National Park (Patagonia). Morphometrics and genetic markers of mitochondrial cytochrome oxidase (COI) and ribosomal internal transcribed spacer 1 (ITS1) confirmed that adults and metacercariae were conspecific and represent a new species, Cryptocotyle dominicana n. sp. The only congener known from South America (Cryptocotyle thapari McIntosh, 1953) matures in river otters (Lutra spp. and Pteronura spp.) in Brazil and Bolivia and differs from the new species in the arrangement of the testes, which are located in tandem in the species from otters. Adults of the new species resemble Cryptocotyle lingua (Creplin, 1825) Fischoeder, 1903 from marine environments of the Northern Hemisphere, both species being characterized by having a linguiform body, oblique testes, and vitelline follicles that extend posteriorly to the level of the ventral sucker. Considering the morphological findings that differentiate the new species from other Cryptocotyle, as well as the molecular analysis that shows significant differences from C. lingua, we conclude that these specimens represent a new species, the first of the genus Cryptocotyle to be described from birds in South America.

The Behavior Response of Amphipods Infected by Hedruris suttonae (Nematoda) and Pseudocorynosoma sp. (Acanthocephala).

The manipulation of intermediate host behavior may increase chances of parasite transmission to the definitive host. In freshwater environments of the Neotropical Region, studies on behavioral manipulations by parasites are rare, and the majority of these consider only a single parasite species and/or 1 life stage of a particular parasite species. In Andean Patagonian lakes of Argentina, the amphipod Hyalella patagonica is infected by larvae of the fish nematode Hedruris suttonae and by the bird acanthocephalan Pseudocorynosoma sp. The 3 objectives of the present study were to determine whether H. suttonae and Pseudocorynosoma sp. differ in their effects on behavior of H. patagonica , whether such modification is associated with parasite development, and to assess the associations between behavioral traits. From naturally parasitized amphipods, activity (swimming levels) and phototaxis (light preference) was measured. Only in phototaxis trials did larvae of H. suttonae induce significantly higher levels of photophilia, suggesting that they are manipulative. Scores of activity and phototaxis were positive and significantly related for non-parasitized female amphipods and for amphipods parasitized by larvae of Pseudocorynosoma sp. but were not associated in amphipods parasitized with larvae of H. suttonae (infective and non-infective), suggesting that infection separated the relationship between these variables.