Phenotypic plasticity, genetic structure, and systematic position of Neoechinorhynchus emyditoides Fisher, 1960 (Acanthocephala: Neoechinorhynchidae) a parasite of emydid turtles from the Nearctic and Neotropical regions.

Abstract

AbstractThe taxonomy of the 10 recognizedNeoechinorhynchusspecies associated with emydid turtles is complex due to the morphological conservatism. In the present study, specimens ofN. emyditoidesfrom northern and southeastern Mexico exhibit great phenotypic plasticity on its diagnostic characteristics. We sequenced three molecular markers: the internal transcribed spacers ITS1, ITS2 and 5.8S gene, the D2 + D3 domains of the large subunit from nuclear DNA and cytochromecoxidase subunit I (cox1) from mitochondrial DNA. Sequences of the nuclear molecular markers were aligned and compared with other congeneric species associated with emydids available in GenBank. Phylogenetic analyses supported the polyphyly ofNeoechinorhynchus. The species from emydids formed a clade, which was subdivided into five subclades that correspond with each species analysed (N. pseudemydis,N. chrysemydis,N. emydis,N. schmidtiandN. emyditoides). To understand better the genetic structure ofN. emyditoidesa haplotype network was inferred with 29cox1sequences, revealing the presence of 13 haplotypes, two of which were shared and 11 were unique. The high values of fixation index,Fst(0.4227–0.8925) detected between the two populations from southeastern and the two from northern Mexico indicated low genetic flow among the populations. Our data suggest that theNeoechinorhynchusspecies associated with emydid turtles diversified in the eastern USA and that ofN. emyditoidesexpanded its distribution range reached southeastern Mexico.