Larval Contracaecum sp. (Nematoda: Anisakidae) in the Great Cormorant [Phalacrocorax carbo (L., 1758)] from north-eastern Poland: a morphological and morphometric analysis.

Stomachs of the Great Cormorant (Phalacrocorax carbo) from north-eastern Poland were found to contain adult nematode Contracaecum rudolphii [Hartwich, G., 1964. Revision der Vogelparasitischen Nematoden Mitteleuropas II. Die Gattung Contracaecum Railliet & Henry, 1912. Mitt. Zool. Mus. Berlin 40, 15-53.] sensu lato and nematode larvae which, based on their morphology, were identified as the third (L3) and fourth (L4) stage larvae of Contracaecum sp. Morphology and biometry of the L3 isolated from the Great Cormorant were very similar to those of the L3 of C. rudolphii described by Bartlett [Bartlett, C.M., 1996. Morphogenesis of Contracaecum rudolphii (Nematoda: Ascaridoidea), a parasite of fish-eating birds, in its copepod precursor and fish intermediate hosts. Parasite 4, 367-376.]. In our opinion, L3 and L4 to be larval stages of C. rudolphii. The paper contains detailed descriptions of the L3 and L4 stages of C. rudolphii; the L4 morphology is described in detail for the first time ever. The descriptions are supplemented by drawings and SEM images. Morphology and biometry of larvae were compared with the literature data and discussed.