Cestodes of the horned grebe Podiceps auritus (L.) (Aves: Podicipedidae) from Lake Myvatn, Iceland, with the description of Confluaria islandica n. sp. (Hymenolepididae).

Three cestode species are recorded from Podiceps auritus at Lake Myvatn, Iceland: Tatria minor Kowalewski, 1904 (Amabiliidae), Confluaria furcifera (Krabbe, 1869) and C. islandica n. sp. (Hymenolepididae). C. islandica n. sp. is described on the basis of specimens reported by Baer (1962) as 'Hymenolepis capillaris (Krabbe, 1869)' and newly-collected specimens. It is unique among Confluaria spp. in having: a muscular, thick-walled genital atrium with its proximal end divided into male and female canals; distinct microtriches covering the surface of the rhynchus; and a short, cylindrical cirrus. The shape and the total length of the rostellar hooks are most similar to those of C. capillaris (Rudolphi, 1810), but differ in having a long handle and a relatively small epiphyseal thickening rather than a short handle and the large epiphyseal thickening. The allopatry of the NE Atlantic population of P. auritus is believed to have been a prerequisite for the formation of its specific helminth fauna. Both C. furcifera and T. minor are recorded for the first time in Iceland.