The metazoan parasite fauna of yellow perch (Perca flavescens Mitchell) in Alberta

Bibliography: p. 96-103

\u3ci\u3eHalipegus eschi\u3c/i\u3e n. sp. (Digenea: Hemiuridae) in \u3ci\u3eRana vaillanti\u3c/i\u3e from Guanacaste Province, Costa Rica

Halipegus eschi n. sp. is described from the esophagus of Rana vaillanti from Guanacaste Province, Costa Rica. The new species differs from other known species of Halipegus on the basis of relative testis size, lateral extent of the uterus, vitelline follicle arrangement, egg size, and polar filament length

Morphological and Molecular Description of \u3ci\u3eHaematoloechus meridionalis\u3c/i\u3e n. sp. (Digenea: Plagiorchioidea: Haematoloechidae) from \u3ci\u3eRana vaillanti\u3c/i\u3e Brocchi of Guanacaste, Costa Rica

An undescribed species of Haematoloechus inhabits the lungs of Rana vaillanti in northwestern Costa Rica. The new species is most similar morphologically to H. medioplexus, having a very small, but well-developed, ventral sucker and lacking extracecal uterine loops, and apparently was misidentified previously as H. medioplexus in Rana palmipes from Colombia. It differs from H. medioplexus, notably by (1) the shape of the oral sucker, which is elliptical in H. meridionalis and spherical in H. medioplexus; (2) the posterior extent of the vitelline fields, which terminate at the same level in H. medioplexus, but always at different levels in H. meridionalis; (3) the position of the testes, which are immediately posterior to the seminal receptacle and are close together in the new species and far from the seminal receptacle and separated from each other in H. medioplexus; and (4) the location of the genital pore, which is ventral to the cecal bifurcation in the new species and ventral to the pharynx in H. medioplexus. In addition, the new species is unique among members of Haematoloechus by having flaps of tissue on the interior margins of the ventral sucker. The new species shows almost 5% sequence divergence from H. medioplexus in the variable Dl region of the 28s rDNA, complementing the morphological differences

Ecological Fitting as a Determinant of the Community Structure of Platyhelminth Parasites of Anurans

Host-parasite associations are assumed to be ecologically specialized, tightly coevolved systems driven by mutual modification in which host switching is a rare phenomenon. Ecological fitting, however, increases the probability of host switching, creating incongruences between host and parasite phylogenies, when (1) specialization on a particular host resource is a shared characteristic of distantly related parasites, and (2) the resource being tracked by the parasite is widespread among many host species. We investigated the effect of ecological fitting on structuring the platyhelminth communities of anurans from a temperate forest and grassland in the United States and tropical dry and wet forests in Mexico and Costa Rica. The six communities all exhibit similar structure in terms of the genera and families inhabiting the frogs. Parasite species richness is highly correlated with the amount of time a host spends in association with aquatic habitats, a conservative aspect of both parasite and host natural history, and determined in a proximal sense by host mobility and diet breadth. The pattern of parasite genera and families within host genera across the regions examined is consistent with the prediction that ecological fitting by phylogenetically conservative species, coupled with historical accidents of speciation and dispersal, should be evidenced as a nested subset structure; the shared requirement for aquatic habitats of tadpoles provides a baseline assemblage to which other parasite taxa are added as a function of adult host association with aquatic habitats. We conclude that parasite communities are structured by both ecological fitting and coevolution (mutual modification), the relative influences of which are expected to vary among different communities and associations

Morphological and molecular description of Haematoloechus meridionalis n. sp. (Digenea: Plagiorchioidea: Haematoloechidae) from Rana vaillanti Brocchi of Guanacaste, Costa Rica.

Ficha diagnostica del holotipo de Haematoloechus meridionalis, especie descrita en este protologo