Abstract: Aplectana hylambatis is a nematode with a wide geographic distribution and low host specificity. In spite of numerous reports, until this moment, the morphological variations between different hosts and localities have not been studied. We studied 401 specimens collected from five host species from seven localities in Argentina, and examined the following morphological characters: mamelon-like cuticular protuberances anterior to the vulva, structure of the gubernaculum and the spicules, number and arrangement of caudal papillae, and the measurements of twelve characters in females and eleven characters in males. The results showed that mamelon-like protuberances and caudal papillae varied in number and arrangement between different hosts and localities. The metrical study revealed that five characters in males and six in females contributed to variability; nine characters showed significant differences between host species and localities. Specimens of A. hylambatis collected from R. arenarum formed a group clearly differentiated from the rest of the specimens. The results from this study highlight the importance of examining as many specimens as possible from different host samples and from several localities to cover the intraspecific variations.

Abstract: The goal of the present study was to analyze the metacercariae found in adult amphibians collected in the Argentinean Chaco region. A total of 194 frogs, Leptodactylus chaquensis, Leptodactylus latinasus, and Lepidobatrachus laevis was examined for digeneans. Three different larval trematodes of the genus Strigea (Digenea, Strigeidae) were found infecting the liver, mesentery, body cavity, and muscle of frogs. These metacercariae are described and illustrated for the first time and provide new information on the composition of metacercariae in amphibians, thus contributing to the knowledge of larval trematodes biodiversity in the Neotropical region. We also present new information on the morphology and morphometry of strigeid metacercariae.

Desde febrero de 2002 a diciembre de 2004, se analizó la fauna de helmintos parásitos y las características reproductivas de Scinax nasicus en un área cercana a la ciudad de Corrientes, Argentina. La fauna de parásitos helmintos estuvo conformada por 15 especies de helmintos (larvas y adultos) incluyendo trematodes (73%), nematodes (20%) y acantocéfalos (7%). La especie Opisthogonimus sp. presentó la mayor prevalencia (41%) de infección. Los hospedadores definitivos de esta metacercaria son probablemente las serpientes. Scinax nasicus, interviene como segundo hospedador intermediario, infectándose por la penetración directa de cercarias. El número de óvulos maduros por hembra (complemento ovárico) osciló entre 413-3922, mientras que el diámetro medio de los óvulos fue de 0,76 ±0,17mm. Esta especie posee un patrón reproductivo prolongado.

From February 2002 to December 2004, the helminth parasite fauna and reproductive features of the frog Scinax nasicus were studied from Corrientes city, Province of Corrientes, Argentina. The parasite richness was 15 species of helminths (larval and adult) including trematodes (73%), nematodes (20%) and acanthocephalans (7%). Opisthogonimus sp. showed the highest prevalence (41%). The definitive hosts of these larval trematodes are probably snakes; S. nasicus acts as second intermediate host, and become infected by direct penetration of cercariae. The number of mature ova per female ranged from 413 to 3922, and the mean mature ovum diameter was 0.76 ±0.17mm. This species has a prolonged reproductive pattern.

Desde fevereiro de 2002 a dezembro de 2004, se analisou a fauna de helmintos parasitos e as características reprodutivas de Scinax nasicus em uma área perto da cidade de Corrientes, Argentina. A fauna de parasitos helmintos esteve conformada por 15 espécies de helmintos (larvas e adultos) incluindo trematodes (73%), nematodes (20%) e acantocéfalos (7%). A espécie Opisthogonimus sp. apresentou a maior prevalência (41%) de infecção. Os hospedadores definitivos desta metacercária são provavelmente as serpentes. Scinax nasicus, intervem como segundo hospedador intermediario, infectando-se pela penetração direta de cercarias. O número de óvulos maduros por fêmea (complemento ovárico) oscilou entre 413-3922, enquanto que o diâmetro médio dos óvulos foi de 0,76 ±0,17mm. Esta espécie possui um padrão reprodutivo prolongado.