Metacercariae in the brain of Erythrinus cf. erythrinus (Characiformes: Erythrinidae) from Iguazú National Park (Argentina): do they belong to Dolichorchis lacombeensis (Digenea, Diplostomidae)?

MONTES, MIGUEL MARTIN; CROCI, YASMIN; SANTOPOLO, LUCIA GRISEL; BARNECHE, JORGE; FERRARI, WALTER; CARDARELLA REIG,GERMAN F.; MARTORELLI, SERGIO

JOURNAL OF HELMINTHOLOGY

CAMBRIDGE UNIV PRESS

Lugar: Cambridge; Año: 2022

0022-149X

In Argentina, the family Diplostomidae is composed of eight genera:Austrodiplostomum Szidat & Nani, Diplostomum von Nordmann, Dolichorchis Dubois,Hysteromorpha Lutz, Neodiplostomum Railliet, Posthodiplostomum Dubois,Sphincterodiplostomum Dubois and Tylodelphys Diesing. During a parasitologicalsurvey of fishes from the Iguazú national park we detected diplostomid metacercariae inthe brain of Erythrinus cf. erythrinus. Fish were caught using nasa traps, transportedalive to the field laboratory, cold-anesthetized and euthanized by cervical dissection.Some metacercariae were heat-killed in water and fixed in 10% formalin and otherswere preserved in alcohol 96% for DNA extraction. They were sequenced for the partialsegment of the 28S rDNA, ITS rDNA and COI mtDNA genes. Phylogeneticreconstruction was carried out using Bayesian Inference (BI) and the proportion (p) ofabsolute nucleotide sites (p-distance) was obtained. In the 28S rDNA tree, themetacercaria sequenced grouped Dolichorchis sp. The COI mtDNA p-distance betweenthe metacercariae with Dolichorchis lacombeensis was 0.01. There is a small number ofITS sequences for the Diplostomidae family deposited in the Genbank. The oral sucker,ventral sucker, holdfast organ and the distance between oral and ventral suckers arelarger in the adult compared with the metacercariae. Additionally, hindbody length andwidth are larger in the adult due to the development of the genital complex. Furtherstudies using an integrative approach will help confirm the affiliation of other species tothe genus Dolichorchis.