Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Ascocotyle (A.) nunezae n. sp. (Digenea: Heterophyidae) from Yucatan, Mexico.

Abstract

A new heterophyid species, Ascocotyle (Ascocotyle) nunezae sp. nov., is described from adults found in the intestine of a naturally infected heron (Casmerodius albus) from the coastal lagoon of Celestún, Yucatan, Mexico. Adults of this species were also obtained from domestic chicks (Gallus gallus) experimentally infected with metacercariae from the cichlid fish Cichlasoma octofasciatum. The new species is characterized mainly by the number (32-37) and arrangement of circumoral spines, which form 1 complete row of 25-27 circumoral spines and 6-10 accessory spines on the dorsal side, and by the morphology of the ventrogenital sac with a large gonotyl consisting of 2 indistinctly separated lobes of vesicular tissue. A. nunezae is placed into the nominotypical subgenus Ascocotyle because of the presence of uterine loops at the pharyngeal region and the position of vitelline follicles. However, it differs markedly from other members of this subgenus by the presence of long intestinal caeca reaching posterior to the ventral sucker. Fish of the genus Cichlasoma from cenotes, lakes and the river Río Hondo in the Yucatan Peninsula were found to be natural second intermediate hosts of A. nunezae, with metacercariae encysted on their gills. C. meeki was the most heavily infected of these fish hosts (prevalence 75%, mean intensity 11±9 worms/fish).