Species of the nematode genus Amidostomum Railliet and Henry, 1909 in aquatic birds in the Netherlands.

The presence of gizzard worms belonging to the genus Amidostomum was studied in birds in the Netherlands during the period 1975-2003. Amidostomum acutum was found in Anatidae: Anas acuta, A. clypeata, A. crecca, A. penelope, A. platyrynchos, A. strepera, Aythya ferina, Ay. fuligula, Ay. marila, Bucephala clangula, Melanitta fusca, M. nigra, Tadorna tadorna, Somateria mollissima and Recurvirostra avocetta. No Amidostomum species were found in the following three species of Mergini: Mergus albellus, M. merganser and M. serrator. Amidostomum anseris was seen in Anser albifrons, A. fabolis, Branla bernicla and Branta leucopsis. Amidostomum cygni was detected in Cygnus bewickii and Cygnus olor, while Amidostomum fulicae was found in Fulica atra. The prevalence is only given for bird species where ten or more individuals had been investigated: Anas platyrhynchos (n = 14): 21.4%; Melanitta nigra (n = 12): 91.7%; Somateria mollissima (n = 117): 100%; Anser albifrons (n = 11): 100% and Cygnus olor (n = 10): 60%. Based on the present results, much more attention should be paid to the systematics, the epidemiological pattern and the pathogenicity of worms of this genu