Revalidation of Saccocoelioides bacilliformis (Digenea, Haploporidae) parasitizing species of Astyanax (Characiformes, Characidae) from southern Brazil

Abstract

In Argentina, Saccocoelioides bacilliformis Szidat, 1973 was described from specimens collected probably in Astyanax bimaculatus (Linnaeus, 1758), but latter it was synonymyzed with Saccocoelioides octavus Szidat, 1970. During the examination of digenetic trematodes collected in different species of Astyanax Baird & Girard, 1854 from southern Brazil, we found specimens identified as Saccocoelioides. A detailed comparison of the morphology of the two species revealed that they should be considered valid, thus this study proposes the revalidation of S. bacilliformis. The traits that allowed the revalidation were: body shape, position of the caecal bifurcation, and the extension of the uterus and vitellarium. Parameters of infections are provided for the first time in addition to records of new hosts and new locality.

Saccocoelioides kirchnerin. sp. (Digenea: Haploporidae) from the killifishCnesterodon decemmaculatus(Cyprinodontiformes: Poeciliidae) from Argentina, morphological and molecular description

“…We consider two reported species from Argentina to be controversial. Saccocoelioides baciliformis Szidat, 1954 was synonymized with S. octavus (Lunaschi, 2002) but recently Gallas & Utz (2019) recognize S. baciliformis as a valid species based on their morphological observations from new material recovered from Brazil. In a recent work, Curran et al (2018) advocated the importance of addressing the condition of existing type-materials, the need for new specimen collections and the need for applying molecular tools for discrimination among Saccocoelioides spp.…”

Host-induced phenotypic plasticity in Saccocoelioides lamothei Aguirre-Macedo and Violante-González, 2008 (Digenea: Haploporidae) a parasite of freshwater, brackish and marine fishes from Middle America

“…Saccocoelioides Szidat, 1954 is the most diverse genus of trematodes belonging to the subfamily Chalcinotrematinae, and includes 24 recognized species, of which 14 are distributed in South America, seven in Middle America, two in North America and one in Puerto Rico; all these species are associated with freshwater, brackish and marine fishes from 10 families (Curran et al ., 2018; Andrade-Gómez et al ., 2019; Gallas and Utz, 2019). The genetic library of species of Saccocoelioides has increased significantly in the last few years.…”