The Acanthocephala of Wild Ducks in Central Illinois, with Descriptions of Two New Species

Abstract

The junior author of this paper made a field study of the worm parasites of wild ducks in central Illinois during the open season of 1935, from October 21 to November 21. In the course of this study, the digestive tracts of 56 ducks, representing 8 species, were examined in the laboratory for worm parasites. Twenty-one of these birds were infected with Acanthocephala which occurred in 5 of the species in numbers ranging from a single worm to about 200 in the individual intestine. Five species of Acanthocephala are represented in this material, two of which are described in this paper as new species. Polymorphus minutus, a species widely distributed in Europe, is here recorded for the first time from a North American host. Corynosoma constrictum and Polymorphus marilis, characteristic species of American ducks, are recorded from new hosts and a new locality. In the present study about 37 per cent of the ducks were parasitized with Acanthocephala. Of the individual species the numbers examined were too small to give significant figures on the incidence of infection. The five species of ducks carrying Acanthocephala were: the mallard (Anas platyrhynchos platyrhynchos), the pintail (Dafila acuta), the ruddy duck (Erismaturajamaicensis rubida), the green-winged teal (Nettion carolinensis) and the hooded merganser (Lophodytes cucullatus). Three species of duck, each represented by one or two autopsies, were not infected with Acanthocephala as follows: 2 black ducks (Anas rubipes tristis), 1 wood duck (Aix sponsa) and 1 buffle head (Charitonetta albeola). The last two species were likewise free from other worm parasites. Mixed infections of Acanthocephala were encountered although these are relatively infrequent in former records. Corynosoma constrictum and Polymorphus marilis occurred together in one mallard and Polymorphus minutus and P. marilis were associated in another mallard.