title: Petasiger islandicus n. sp. (Digenea: Echinostomatidae) in the horned grebe Podiceps auritus (L.) (Aves: Podicipedidae) from Iceland.
abstract: Petasiger islandicus n. sp. is described and figured from a demographically isolated population of the horned grebe Podiceps auritus auritus (L.) in Lake Mývatn (Iceland). This new species belongs to the group of species with 19 collar spines which possess a large elongate-oval cirrus-sac, well-developed pars prostatica and massive bulb-like cirrus. Within this group, P. islandicus appears most similar to P. oschmarini Kostadinova & Gibson, 1998, a form with similar body dimensions described from the same host, but differs in having a larger head collar, collar spines, oral sucker, pharynx, testes and sucker-width ratio, and a smaller cirrus-sac, cirrus and eggs. Two Nearctic species resemble P. islandicus in general morphology but differ as follows: P. pseudoneocomense Bravo-Hollis, 1969 has a larger body and collar width, notably shorter collar spines, smaller testes and sucker-width ratio, and a shorter but much wider cirrus-sac which is also smaller relative to the ventral sucker and almost entirely anterior to it; and P. caribbensis Nassi, 1980 has a smaller body, shorter collar spines and a seminal vesicle which is small in relation to the cirrus-sac, vitelline fields reaching anteriorly to the level of the genital pore and the intestinal bifurcation is located more anteriorly.
authors: Central Laboratory of General Ecology, Bulgarian Academy of Sciences, 2 Gagarin Street, 1113 Sofia, Bulgaria. Aneta.Kostadinova@uv.es
authors: Aneta
authors: A
authors: Kostadinova
authors: Karl
authors: K
authors: Skirnisson
mesh_terms: D000818:Animals; D001715:Bird Diseases / Q000469:parasitology*; D001717:Birds / Q000145:classification / Q000469:parasitology*; D004450:Echinostomatidae / Q000033:anatomy & histology / Q000145:classification*; D007055:Iceland; D013045:Species Specificity; D014201:Trematode Infections / Q000469:parasitology / Q000662:veterinary*