Molecular evidence linking the larval and adult stages of Mexiconema cichlasomae (Dracunculoidea: Daniconematidae) from Mexico, with notes on its phylogenetic position among Dracunculoidea

Abstract

AbstractWe describe the larval developmental stages and life cycle of the dracunculid nematodeMexiconema cichlasomaein both the intermediate,Argulus yucatanus(Crustacea: Branchiura), and definitive hosts,Cichlasoma urophthalmus(Perciformes: Cichlidae), from the Celestun tropical coastal lagoon, Yucatan, Mexico. The morphological analyses showed significant differences between the total length of L1 found inM. cichlasomaegravid female and L2–L3 inA. yucatanus.This result indicates that theM. cichlasomaelarval development occurs in the intermediate host. We obtained sequences from the small subunit (SSU) ribosomal marker from larval stages ofM. cichlasomaeinA. yucatanusand adult nematodes inC. urophthalmus. Our morphological and molecular results support conspecificity betweenM. cichlasomaelarvae inA. yucatanusand the adult stages inC. urophthalmus. We briefly discuss the phylogenetic position ofM. cichlasomaeamong the Daniconematidae, and provide evidence of the monophyly of the daniconematids associated with branchiurid intermediate hosts. Based on the phylogenetic results, we support the transfer of theMexiconemagenus to the family Skrjabillanidae and do not support the lowering of family Daniconematidae to subfamily.