Morphological and molecular assessment of the diversity of trematode communities in freshwater gastropods and bivalves in Los Tuxtlas tropical rainforest

Abstract

Trematode life cycles involve molluscs as first intermediate hosts. The identification of trematodes based on the morphology of cercariae released from molluscs is challenging because the identification relies on adult forms obtained from their definitive hosts. Several studies have recently genetically characterized these larval forms establishing a link with adults sampled from their vertebrate hosts, allowing their identification at species level. In Los Tuxtlas tropical rainforest, in south-eastern Mexico, 57 species of trematodes have been reported from wildlife vertebrates; however, studies evaluating the diversity of trematode cercariae in molluscs are lacking. Here, we studied 11 species of molluscs to assess the diversity of cercariae in two lakes of Los Tuxtlas, Veracruz, Mexico; six of the 11 species were infected. Twelve cercarial morphotypes were collected and characterized morphologically. Sequences of the 28S ribosomal RNA gene were generated to allocate each morphotype into a family using the most recent phylogenetic classification of the Digenea as a framework; molecular work revealed 16 genetic lineages; some cercariae were identified up to genus (Apharyngostrigea, Ascocotyle, Centrocestus, Echinochasmus, Lecithodendrium and Posthodiplostomum), and some to species levels (Gorgoderina rosamondae, Langeronia macrocirra, Oligogonotylus manteri and Phyllodistomum inecoli) based on their phylogenetic position within the tree, and the genetic distance with respect to other sequenced congeners. Therefore, the cercarial morphotypes in the present study represent at least 16 putative species. Our study contributes to a better understanding of the trematode diversity in an area of high vertebrate species diversity, and to the knowledge of trematode life cycles.

First integrative study of the diversity and specificity of metacercariae of Posthodiplostomum Dubois, 1936 from native and introduced fishes in the Caribbean

“…Among the snails collected, Physa acuta is therefore the most likely first-intermediate host of the Posthodiplostomum species observed in Poe. reticulata and D. monticola , in view of prior records of Posthodiplostomum and similar neascus-forming species in members of the Hygrophila such as Physidae and Planorbidae (Hoffman, 1960; Ostrowski de Núñez, 1973; Velázquez-Urrieta and Pérez-Ponce de León, 2021). The absence of infections in 747 Ph.…”

Morphological, molecular, and life cycle study of a new species of Oligogonotylus Watson, 1976 (Digenea, Cryptogonimidae) from Colombia

“… mayae use the cochliopid snail P. coronatus (misidentified as Benthonella gaza ), and that O. manteri also uses the cochliopid snail Aroapyrgus alleei Morrison, 1946 as the first intermediate host and the cichlid fish M. urophthalmus either as the second intermediate or the main definitive host among other 11 species of cichlids ( Scholz et al 1994 ; Jiménez-García and Vidal-Martínez 2005 ; Pérez-Ponce de León et al 2007 ; May-Tec et al 2020 ; Velázquez-Urrieta and Pérez-Ponce de León 2021 ). Oligogonotylus andinus sp.…”

“… latifrons ) is the definitive host; thus, the present work extends the Oligogonotylus – Cochliopidae – Cichlidae association. Therefore, species of Oligogonotylus are still considered as members of the core helminth fauna of cichlids ( Pérez-Ponce De León and Choudhury 2005 ), but also as members of the core helminth fauna of cochliopids ( May-Tec et al 2020 ; Velázquez-Urrieta and Pérez-Ponce de León 2021 ; present study).…”

High prevalence of natural infection by the ruminant blood fluke Schistosoma spindale in the intermediate snail host Indoplanorbis exustus in Uttaradit, Northern Thailand

“…While morphological characteristics can be used to classify trematode cercariae and potentially group larval flukes at the family level, certain morphotypes, such as furcocercous cercariae, are found across several families, including Diplostomidae , Sanguinicolidae , Strigeidae , Clinostomidae , and Schistosomatidae [ 13 ]. Molecular approaches are promising for precisely identifying the trematode cercariae.…”