Parasites have been used as a tool to study the phylogeny of avian hosts (e.g. Baer and Mayr 1957). Differences between the parasite faunas of two host species could reflect differences in genetic susceptibility to the parasites or could be the result of differences in host feeding habits, habitat preferences, or behaviors. While studying habitat partitioning among 38 antbird species in eastern Ecuador, we collected the birds' trematode parasites. We were particularly interested to learn what ecological and taxonomic conclusions might be drawn from the trematode distributions among the hosts. Methods and Materials.-Antbirds were collected from September 1975 through November 1976 in a relatively undisturbed moist tropical forest (sensu Holdridge 1967) in the vicinity of Limoncocha, a village in the Provincia Napo in east-central Ecuador (0?24'S, 76?37'W; 300 m elevation). Specimens of antbirds that served as hosts are housed at the Louisiana State University Museum of Zoology, Baton Rouge, and at the Universidad Catolica, Quito. Hosts were examined for parasites as soon as possible after being killed (never more than 8 h after death). We examined the digestive tract and associated organs, lungs, air sacs, body cavity, kidneys and associated ducts, and the female reproductive tract. Differences in parasite populations from different hosts were evaluated using a one-way analysis of variance (ANOVA). Results. -Thirty-eight species of antbirds have been reported from Limoncocha, Ecuador (Table 1). We examined 358 specimens of 35 antbird species for parasites. Of these, 123 individuals of 27 species contained trematodes. Eleven trematode species were extracted from the antbirds. The occurrence of these parasites ranged from rare (of incidental distribution and in small numbers), to intermediate (in scattered hosts and with larger numbers of individuals per host), and to common (widely distributed among hosts and found in large numbers). A list of parasites, hosts, incidence of infections, and infection sites is provided in Table 2. Two trematode species were rare among the antbirds. Two immature specimens of Echinostomatidae were found in the kidneys of one Myrmeciza hyperythra host, and one gravid specimen of an undetermined species of Brachylaimidae was retrieved from one Formicarius analis. Six parasites were intermediate in occurrence. Lubens lubens was found in Gymnopithys, Thamnomanes, and Phlegopsis hosts. The measurements of these specimens greatly overlapped. Hylophylax gall bladders contained a much smaller Lubens, which possibly could be a distinct species, but probably is a size variant of L. lubens, since L. lubens is a variable species (Travassos 1944; see Table 3). Although formerly unreported from Formicariidae, L. lubens is known from a wide variety of birds (Travassos et al. 1969). Neodiplostomum ellipticum was found in moderate numbers in two individuals of Percnostola leucaspis. These trematode specimens fit the description for N. ellipticum given by Travassos et al. (1969). Neodiplostomum ellipticum is known from Brazil, Venezuela, and Jamaica from anis (Crotophaga ani and C. major) and the Squirrel Cuckoo (Piaya cayana), all of which occur at Limoncocha (Travassos et al. 1969, Yamaguti 1958). The Neodiplostomum specimens from Myrmeciza (Table 4) were consistently much larger than N. ellipticum or any other Brazilian Neodiplostomum described by Travassos et al. (1969), with the exception of N. tamarini, a parasite of primates. However, N. tamarini has the posterior testis with a median lobe, a characteristic absent in the Myrmeciza trematode specimens. For these reasons, we believe the Neodiplostomum specimens found in Myrmeciza represent an undescribed species. Brachylecithum rarum was found in the livers of Formicarius and Chamaeza hosts. Our material from Formicarius is similar to that figured in Travassos et al. (1969) and in Denton and Byrd (1951). Although the eggs in our sample appear to be relatively small, the measurements for all other features overlap those reported in the literature for Brachylecithum rarum (Table 5). These parasites were easily fragmented. We have no whole specimens from Chamaeza; the measurements of these fragmented worms suggest they are not statistically different from Brachylecithum in Formicarius. The parasite is known from Brazil, where it has been recovered from bile capillaries of various members of the order Passeriformes (Travassos et al. 1969), and from North America, where it has been found in Rufous-sided Towhees (Pipilo erythrophthalmus; Denton and Byrd 1951). An unidentified species of Leucochloridium occurred in Hylophylax, Myrmeciza, Myrmoborus, and Myrmotherula. Although similar in shape to L. parcum from Brazil, our material is larger bodied, with a smaller acetabulum and oral sucker, and much smaller eggs (Table 6). Despite small sample sizes from different hosts, there is little variation among the specimens. We suspect that these specimens represent an undescribed species of Leucochloridium.
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Jan 1, 2016
Tony Eprile 
Open Access