<abstract xmlns="http://www.w3.org/1999/xhtml">

<p>The trematodes of Allocreadiidae are mainly parasites of freshwater fish and the family contains 18 valid genera. Since 2004, 4 genera have been described in the Americas: <italic>Paracreptotrema</italic>, <italic>Paracreptotrematoides</italic>, <italic>Pseudoparacreptotrema</italic> and <italic>Auriculostoma</italic>, of which the latter was recently synonymized with <italic>Creptotrema</italic> by <xref ref-type="bibr" rid="j_helm-2022-0029_ref_019">Franceschini et al., (2021)</xref>. During a study in 2018 on fish parasites of Lacantún River, Chiapas, Mexico, allocreadiids were collected from the intestine of <italic>Atherinella alvarezi</italic> and morphological differences with other genera of the family were immediately noted. These differences were corroborated with molecular data and phylogenetic analyses, which indicated that it was a new genus and species. The objective of this study is to describe the new taxon, which we name <italic>Mesoamericatrema magnisacculus</italic> n. gen., n. sp. as well as to clarify its phylogenetic relationships, host specificity, and geographical distribution. For this, we carried out a meticulous study of the morphology and compared the new taxon with its congeners. We also obtained sequences of the 28S and ITS from the ribosomal RNA region that were used in generating molecular phylogenies and in calculating genetic distances with sequences of other species of Allocreadiidae available in the Genbank. The new genus is mainly characterized by having a very large cirrus sac in relation to the length of its body and nests in a clade that groups <italic>Creptotrema</italic>, <italic>Creptotrematina</italic>, <italic>Paracreptotrema</italic>, <italic>Paracreptotrematoides</italic>, <italic>Pseudoparacreptotrema</italic> and <italic>Wallinia</italic>, all of which have a Neotropical affinity in terms of their geographic and host distribution. <italic>Mesoamericatrema</italic> n. gen. is the fifth genus of Allocreadiidae to be described in the Americas since 2004, the third discovered in Mexico since 2016, and the first to be described as parasitizing Atheriniformes, which indicates that Middle America is a region where important speciation events have occurred in freshwater fish parasites.</p></abstract>

The trematodes of Allocreadiidae are mainly parasites of freshwater fish and the family contains 18 valid genera. Since 2004, 4 genera have been described in the Americas: Paracreptotrema, Paracreptotrematoides, Pseudoparacreptotrema and Auriculostoma, of which the latter was recently synonymized with Creptotrema by Franceschini et al., (2021). During a study in 2018 on fish parasites of Lacantún River, Chiapas, Mexico, allocreadiids were collected from the intestine of Atherinella alvarezi and morphological differences with other genera of the family were immediately noted. These differences were corroborated with molecular data and phylogenetic analyses, which indicated that it was a new genus and species. The objective of this study is to describe the new taxon, which we name Mesoamericatrema magnisacculus n. gen., n. sp. as well as to clarify its phylogenetic relationships, host specificity, and geographical distribution. For this, we carried out a meticulous study of the morphology and compared the new taxon with its congeners. We also obtained sequences of the 28S and ITS from the ribosomal RNA region that were used in generating molecular phylogenies and in calculating genetic distances with sequences of other species of Allocreadiidae available in the Genbank. The new genus is mainly characterized by having a very large cirrus sac in relation to the length of its body and nests in a clade that groups Creptotrema, Creptotrematina, Paracreptotrema, Paracreptotrematoides, Pseudoparacreptotrema and Wallinia, all of which have a Neotropical affinity in terms of their geographic and host distribution. Mesoamericatrema n. gen. is the fifth genus of Allocreadiidae to be described in the Americas since 2004, the third discovered in Mexico since 2016, and the first to be described as parasitizing Atheriniformes, which indicates that Middle America is a region where important speciation events have occurred in freshwater fish parasites.

Discovery of a new genus and species of Allocreadiidae (Trematoda) in Mexico: <italic>Mesoamericatrema magnisacculus</italic> n. gen. n. sp

Helminthologia

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Discovery of a new genus and species of Allocreadiidae (Trematoda) in Mexico:  n. gen. n. sp

The trematodes of Allocreadiidae are mainly parasites of freshwater fish and the family contains 18 valid genera. Since 2004, 4 genera have been described in...

Discovery of a new genus and species of Allocreadiidae (Trematoda) in Mexico: Mesoamericatrema magnisacculus n. gen. n. sp

Article Category: Research Article

Published Online: Dec 17, 2022

Page range: 284 - 300

Received: Aug 03, 2022

Accepted: Aug 30, 2022

DOI: https://doi.org/10.2478/helm-2022-0029

Keywords
phylogeny, Chiapas, Allocreadiidae, new genus,

© 2022 B. Mendoza-Garfias, J. G. García-Teh, J. M. Caspeta-Mandujano, V. M. Vidal-Martínez, D. I. Hernández-Mena, published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Discovery of a new genus and species of Allocreadiidae (Trematoda) in Mexico: Mesoamericatrema magnisacculus n. gen. n. sp

Article Category: Research Article

Published Online: Dec 17, 2022

Page range: 284 - 300

Received: Aug 03, 2022

Accepted: Aug 30, 2022

DOI: https://doi.org/10.2478/helm-2022-0029

Keywordsphylogeny, Chiapas, Allocreadiidae, new genus,

© 2022 B. Mendoza-Garfias, J. G. García-Teh, J. M. Caspeta-Mandujano, V. M. Vidal-Martínez, D. I. Hernández-Mena, published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Keywords
phylogeny, Chiapas, Allocreadiidae, new genus,