Advances in the knowledge of Echinoparyphium megacirrus and Echinostoma sp. (Digenea: Echinostomatidae) parasites of Diplodon chilensis (Pelecypoda) in Patagonia (Argentina).

FLORES V.R.; SEMENAS L.G.

Revista Argentina de Parasitología

Asociación Argentina de Parasitología

Lugar: La Plata; Año: 2016 vol. 5 p. 11 - 20

2313-9862

Diplodon chilensis (Pelecypoda, Hyriidae) is the only species present in the Patagonian Region ofthe Neotropical endemic genus Diplodon. Metacercariae of genera Echinostoma and Echinoparyphium havebeen found in this bivalve species and in the snail Lymnaea viatrix. The aim of this work was to evaluatethe characteristics of the infestations and the geographic distribution of Echinoparyphium megacirrus andEchinostoma sp., parasites of D. chilensis in Andean-Patagonian environments and to advance in the knowledgeEchinostoma sp. A total of 19 environments (39°06?S - 42°36?S) were sampled in order to collect specimensof D. chilensis to record the presence of metacercariae and to perform experimental infestations in Gallusgallus domesticus with parasitized viscera. The distribution range of E. megacirrus and Echinostoma sp. wasdetermined by the study of metacercariae in natural environments, and by experimental ovigerous adults obtainedin infestations with G.g. domesticus. Both species of Echinostomatidae were located mainly in the pericardialcavity, and in hepatopancreas and, gonads of the moluscan host. The measurements and morphology of themetacercariae and adults of E. megacirrus coincide with those of the original description. For Echinostoma sp.metacercariae, diameter and thickness of cyst wall, and size and distribution of the crown spines are differentfrom those previously described in D. chilensis. It is the first time that ovigerous specimens of Echinostomafrom experimental infestations were obtained, indicating that D. chilensis is a suitable secondary host for thisdigenean species. Comparisons of morphology and measurements of the experimental adults obtained withother species of Echinostoma with 37 spines collar, would assign them to Echinostoma chloephagae previouslydescribed in the native Chloephaga picta leucoptera, although the spines in our specimens are smaller.Comparing the presence and infestation values of both metacercariae, E. megacirrus has a wider distributionrange, is recorded in more environments and presents higher prevalences.