Molecular and morphological characterization ofAndracantha gravida(Alegret, 1941) (Acanthocephala: Polymorphidae) in piscivorous birds from the Gulf of Mexico

Abstract

AbstractAdult specimens ofAndracantha gravida(Alegret, 1941) were recorded from the intestines of the double-crested cormorantNannopterum auritus(Lesson) (type host) and brown pelicanPelecanus occidentalisL. in two localities from Mexico: Celestún, Yucatan (south-eastern) and Punta Piedra, Tamaulipas (north-eastern). The specimens ofA. gravidaare morphologically characterized by having a pipe-shaped body without swellings, the absence of small trunk spines between the two fields of spines on the foretrunk and a cylindrical proboscis with 14–16 rows of 10–12 hooks per row. Newly generated partial sequences of the mitochondrial cytochromecoxidase subunit 1 (cox1) gene were generated from adult isolates ofA. gravidafrom Mexico and compared with one sequence ofA. gravidaand with sequences of other polymorphid acanthocephalans available in GenBank. Phylogenetic analyses based on maximum likelihood and Bayesian inference methods of thecox1 dataset placed all the species ofAndracanthain a single clade, with weak support. The analyses of thecox1 dataset placedAndracantha sigmaPresswell, García-Varela & Smales, 2018, as sister to the clade formed byA. gravida,Andracantha phalacrocoracis(Yamaguti, 1939),Andracantha leucocarboiPresswell, García-Varela & Smales, 2018 and an unidentified species ofAndracanthafrom Japan. The newly generatedcox1 sequences ofA. gravidafrom piscivorous birds of Mexico formed a strongly supported clade with the published sequence ofA. gravidafrom the double-crested cormorant from the south-eastern coast of Mexico. The intraspecific genetic divergence among isolates identified asA. gravidaranged from 0.0% to 2.2%. Acox1 haplotype network inferred with 14 sequences revealed the presence of nine haplotypes, two of which were shared between the populations of piscivorous birds from the north-eastern and south-eastern coasts of Mexico and seven of which were unique. The fixation index between the populations from north-eastern and south-eastern Mexico was low (0.06949), which suggests genetic flow. This can be explained by the migration patterns of the brown pelican and the double-crested cormorant along the coasts of the Gulf of Mexico.