First record of the genus Choledocystus(Trematoda: Plagiorchiidae) for amphibians of the Chacoan region in Argentina.

Monika Ines Hamann,Virginia León-Règagnon,María Virginia Fernández,Cynthya Elizabeth González

doi:10.1590/0001-3765202020180384

Monika Ines Hamann, Virginia León-Règagnon + Show 2 more

Open Access

https://doi.org/10.1590/0001-3765202020180384

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Abstract

This is the first record of the trematode Choledocystus incurvatum and Choledocystus elegans in Argentinean amphibians collected in two localities of the Chacoan region. The first trematode species was found infecting the small intestine of Pseudis paradoxa Linnaeus, captured near the city of Corrientes, Corrientes Province; the second species was found infecting the gall-bladder of Lepidobatrachus laevis Budgget, captured in Ingeniero Juárez, Formosa Province. Morphology of these species was studied in detail using light microscopy and scanning electron microscopy (SEM), and compared with previous studies of Brazilian and Venezuelan specimens. Morphological descriptions of these parasites are provided to supplement existing data. Choledocystus incurvatum was characterized using molecular methods by sequencing and analyzing rDNA. Regarding metric characters of C. incurvatum, the Argentinean specimens show some differences in body and egg size (some larger than Venezuelan specimens). For C. elegans the specimen shows smaller body size than Brazilian specimens. SEM observations of C. incurvatum showed tegument covered with triangular spines and confirmed presence of a sucker-like structure around the genital atrium. The morphological and genetic data on C. incurvatum contribute to a more thorough diagnosis of the genus. Moreover, this report represents the first occurrence of this genus in the Argentine Chacoan region.

Highlights

Systematic studies provide the foundation for the knowledge of biodiversity that is necessary to tackle a range of increasingly urgent and applied environmental challenges
We report the presence of two species of genus Choledocystus Pereira & Cuocolo, 1941
The goal of this paper is to provide additional morphological information and a molecular characterization of previously described species of genus Choledocystus on the basis of specimens recovered from anurans captured in the Chacoan region, Argentina

Summary

Introduction

Systematic studies provide the foundation for the knowledge of biodiversity that is necessary to tackle a range of increasingly urgent and applied environmental challenges. The diversity of parasites is characterized by a combination of morphological, physiological, behavioral, life-history, and molecular data. In this context, helminth fauna can be considered as a general model system to elucidate patterns and processes in evolution, ecology and biogeography of fundamental importance across the biosphere (see Hoberg et al 2015). We report the presence of two species of genus Choledocystus Pereira & Cuocolo, 1941. This genus was later considered as a synonym of Glypthelmins Stafford, 1905 (see Yamaguti 1971). Prudhoe & Bray (1982) redefined and presented Choledocystus Pereira & Cuocolo, 1941 as a valid genus, designating C. elegans (Travassos, 1926) as the type species, and attributing the following main characteristics to the genus: uterus extending laterally beyond the caeca and

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