Discovery of Homalometron species (Trematoda: Megaperidae) in sympatry in striped mojarra from Veracruz, Mexico: new species and taxonomic change of Crassicutis archosargi Sparks & Thatcher, 1960

Homalometron parentum sp. nov. and Homalometron dominguezi sp. nov. are described from the striped mojarra Eugerres plumieri (Cuvier, Citation1830), collected from Sontecomapan Lagoon, Veracruz, Mexico. Homalometron parentum sp. nov. differs from all congeners by having vitelline follicles that extend to the forebody and are present in the testicular region, and by possessing a smooth and spineless tegument. Homalometron dominguezi sp. nov. may be distinguished by having vitelline follicles that extend to the anterior part of the body, but are not present in the testicular region, and by having a rough, spineless tegument. Our phylogenetic analyses, based on 28S sequences, revealed that Crassicutis archosargi Sparks & Thatcher, Citation1960 was nested in the Homalometron clade, being the sister species of H. dominguezi sp. nov., H. parentum sp. nov., and H. avis Hernández-Mena et al., Citation2022. This result suggests that C. archosargi should be transferred to Homalometron Stafford, 1904 as H. archosargi comb. nov. Additionally, metacercariae of H. parentum sp. nov. were found in shrimp of the family Atyidae, expanding our knowledge of the intermediate hosts involved in the life cycle of Homalometron. In this study, we found that our new species coexists sympatrically with H. avis as parasites of E. plumieri in the Sontecomapan Lagoon.