Linking Larvae and Adults of Apharyngostrigea cornu, Hysteromorpha triloba, and Alaria mustelae (Diplostomoidea: Digenea) Using Molecular Data

Abstract

Because the taxonomy of trematodes is based on adults, the larval stages of most digeneans cannot be identified to species based on morphology alone. Molecular data provide a means of linking larval stages to known adults. We obtained sequences from the barcode region of cytochrome oxidase I (CO1) from adult and larval parasites of fish, frogs, birds, and mammals across North America. Sequences from adult Apharyngostrigea cornu, Hysteromorpha triloba, and Alaria mustelae (Diplostomoidea: Digenea) from definitive hosts matched those of meta- and mesocercariae from fish and frogs. These data provided new information on the distributions of all 3 parasite species. Metacercariae of A. cornu, which have not been previously reported in North American hosts, were found in Notemigonus crysoleucas, Pimephales notatus, and Catostomus commersonii in the St. Lawrence River. Metacercariae of H. triloba are reported in Canadian waters and in N. hudsonius for the first time. Alaria mustelae is reported for the first time in frogs from Quebec, Canada, and an additional species of Alaria was detected in California. Sequences of internal transcribed spacer rDNA from a subset of specimens support the same species boundaries indicated by CO1 divergence. There was little divergence in CO1 sequences from an unidentified diplostomid species sampled at a large spatial scale.

Completion of the life cycle of Tylodelphys mashonense (Sudarikov, 1971) (Digenea: Diplostomidae) with DNA barcodes and rDNA sequences

“…Our work echoes previous studies (Cribb et al 1998;Pina et al 2009;Locke et al 2011) illustrating the usefulness of a molecular approach in elucidating parasitic life cycles. We linked cercariae and sporocysts from Mindu Dam with adults from Lake Victoria and metacercariae from both localities.…”

“…For example, nuclear ribosomal RNA and cytochrome c oxidase I (CO1) genes have been applied to link different stages of digenean life cycles. However, most studies only link two of the three hosts typically present (Cribb et al 1998;Nolan and Cribb 2005;Pina et al 2009;Locke et al 2011). As such, the present study aimed at linking intramolluscan stages, the metacercariae frequently encountered in fish, and the rarely seen adults of T. mashonense using internal transcribed spacer (ITS) and DNA barcodes.…”

Experimental infection dynamics: using immunosuppression andin vivoparasite tracking to understand host resistance in an amphibian-trematode system

“…We compared these results with effects of chronic corticosterone exposure on infections with two other common trematodes, Echinostoma trivolvis (Cort, 1914) and Alaria sp. 2 (Locke et al, 2011), and over time (4 and 14days after parasite exposure). Finally, to better understand the mechanisms underlying observed changes in susceptibility, we compared leukocyte profiles among treatment groups to identify which, if any, leukocytes contribute to the immune response against these larval trematodes.…”

Diversity, specificity and speciation in larval Diplostomidae (Platyhelminthes: Digenea) in the eyes of freshwater fish, as revealed by DNA barcodes

“…Sequences can clarify whether morphological heterogeneity represents interspecific (BlascoCosta et al, 2014;Faltý nková et al, 2014;Pérez-del-Olmo et al, 2014) or intraspecific variation among metacercariae (Cavaleiro et al, 2012;Otachi et al, 2015). Molecular links to adults from avian definitive hosts are usually needed to identify, rather than merely discriminate, species of metacercariae (Galazzo et al, 2002;Locke et al, 2010aLocke et al, , 2011Georgieva et al, 2013;Pérez-delOlmo et al, 2014). However, even when sequences are obtained from adult diplostomids, often not all species detected in surveys of metacercariae are resolved (Galazzo et al, 2002;Georgieva et al, 2013;Pérez-del-Olmo et al, 2014).…”