A new species of Auriculostoma (Digenea: Allocreadiidae) in South America: life cycle and phylogenetic relationships

Abstract

Auriculostoma is a genus of digenean (Trematoda) whose adults are parasites of Neotropical freshwater fi shes. We describe Auriculostoma ocloya n. sp. using morphological and molecular tools, and we elucidated its life cycle, the fi rst known of a species of this genus. The fi rst intermediate host is the bivalve Pisidium ocloya, the second intermediate host is the amphipod Hyalella sp., and the defi nite hosts are siluriform fi shes. The adult presents a single pair of muscular lobes on either side of the oral sucker with a broad base, stretching from ventrolateral to dorsolateral side, a structure also present in the rest of species of the genus. Nevertheless, the new species differs from all congeners by the combination of several traits, and mainly because on the dorsal side "free" ends of the lobes are absent because they are fused. This is the fi rst study to provide sequence data on larval and adult stages of a species of Auriculostoma. Our phylogenetic analysis demonstrated its basal position among species of the genus. Therefore, integrative morphological, molecular, and life cycle data on other South American species of the genus, would contribute to reveal more patterns in the allocreadiid systematics.

An integrative taxonomy study reveals a rare new species of the genus Creptotrema (Trematoda: Allocreadiidae) in an endangered frog in South America

“…By using molecular evidence, those authors identified the genus Auriculostoma as a synonym of Creptotrema, reallocating all described species of the former Auriculostoma as members of Creptotrema. Therefore, considering the new diagnosis of Creptotrema proposed by Franceschini et al (2021), A. ocloya (Liquin et al 2022), which was described after the new revision of the genus, should now be considered as Creptotrema ocloye n. comb.…”

“…Data on parasites associated with this anuran species include only one study carried out by Forti et al (2020), in which the presence of helminths was reported as a part of an ecological study aimed at reporting the infection by chytrid fungus in relation to forest cover, although macroparasites were not taxonomically identified to species level. One of them was morphologically identified as belonging to the trematode genus Creptotrema Travassos, Artigas & Pereira, 1928. The genus Creptotrema includes parasites of freshwater teleosts and anurans distributed across the Neotropical region (Franceschini et al 2021;Liquin et al 2022). To date, the genus includes 20 valid species (Franceschini et al 2021;Liquin et al 2022), with 16 of those occurring in South Americathat is, the type-species Creptotrema creptotrema Travassos, Artigas & Pereira, 1928, Creptotrema conconae Franceschini, Aguiar, Zago, Yamada, Ebert & Silva, 2021, Creptotrema diagonale (Curran, Tkach & Overstreet, 2011), Creptotrema foliaceum (Curran, Tkach & Overstreet, 2011), Creptotrema guacurarii Montes, Barneche, Croci, Balcazar, Almirón, Martorelli & Pérez-Ponce de León, 2021, Creptotrema lamothei Curran, 2008, Creptotrema lynchi Brooks, 1976, Creptotrema macrorchis (Szidat, 1954), Creptotrema megacetabulare Franceschini, Aguiar, Zago, Yamada, Ebert & Silva, 2021, Creptotrema ocloye (Liquin, Gilardoni, Cremonte, Saravia, Cristóbal & Davies, 2022) n.…”

“…One of them was morphologically identified as belonging to the trematode genus Creptotrema Travassos, Artigas & Pereira, 1928. The genus Creptotrema includes parasites of freshwater teleosts and anurans distributed across the Neotropical region (Franceschini et al 2021;Liquin et al 2022). To date, the genus includes 20 valid species (Franceschini et al 2021;Liquin et al 2022), with 16 of those occurring in South Americathat is, the type-species Creptotrema creptotrema Travassos, Artigas & Pereira, 1928, Creptotrema conconae Franceschini, Aguiar, Zago, Yamada, Ebert & Silva, 2021, Creptotrema diagonale (Curran, Tkach & Overstreet, 2011), Creptotrema foliaceum (Curran, Tkach & Overstreet, 2011), Creptotrema guacurarii Montes, Barneche, Croci, Balcazar, Almirón, Martorelli & Pérez-Ponce de León, 2021, Creptotrema lamothei Curran, 2008, Creptotrema lynchi Brooks, 1976, Creptotrema macrorchis (Szidat, 1954), Creptotrema megacetabulare Franceschini, Aguiar, Zago, Yamada, Ebert & Silva, 2021, Creptotrema ocloye (Liquin, Gilardoni, Cremonte, Saravia, Cristóbal & Davies, 2022) n. comb., Creptotrema pati Lunaschi, 1985, Creptotrema paraense Vicente, Santos & Souza, 1978, Creptotrema platense (Szidat, 1954), Creptotrema schubarti Franceschini, Aguiar, Zago, Yamada, Ebert & Silva, 2021, Creptotrema stenopteri (Mañé-Garzón & Gascón, 1973, and Creptotrema sucumbiosa Curran, 2008.…”

“…are preferentially freshwater fishes belonging to multiple orders (Characiformes, Gymnotiformes, Perciformes, and Siluriformes). A new species of Auriculostoma Scholz, Aguirre-Macedo & Choudhury, 2004 was described from Argentina in 2022 as a parasite of siluriforms, named A. ocloya (Liquin et al 2022). Apparently, the authors were unaware of the publication by Franceschini et al (2021) in which the genus Auriculostoma was synonymized with Creptotrema.…”

“…A new species of Auriculostoma Scholz, Aguirre-Macedo & Choudhury, 2004 was described from Argentina in 2022 as a parasite of siluriforms, named A. ocloya (Liquin et al . 2022). Apparently, the authors were unaware of the publication by Franceschini et al .…”