Seasonal morphological variations in bird schistosomes

The present work is a contribution to the systematics of Bilharziella and Dendritobilharzia. Wildfowl was killed in hunting seasons or found dead in Champagne-Ardenne region, France, and autopsied with focus on schistosomes. Seven Anas platyrhynchos (mallards), one Ardea cinerea (grey heron) and two Cygnus olor (mute swans) were parasitized by Bilharziella. One C. olor was parasitized by Dendritobilharzia Depending on season and hosts, various morphological forms of Bilharziella suggesting several species were observed. The differences in male and female worms concerned the morphology of genital apparatus, the spination on suckers, the body size and proportions. However, the comparison of DNA sequences led to a conclusion that these forms belonged to one species, Bilharziella polonica (Kowalewski, 1895). The morphological features and the body sizes of our samples of Dendritobilharzia seemed to differ from the type species of D. pulverulenta (Braun, 1901). Nevertheless, molecular analysis confirmed identity. We hypothesize that the differences in Bilharziella and Dendritobilharzia might be linked to internal host factors (e.g. hormonal levels), and influenced by season, host, and worm age. The definition of the genera Bilharziella and Dendritobilharzia was amended

Seasonal morphological variations in bird schistosomes

The present work is a contribution to the systematics of Bilharziella and Dendritobilharzia. Wildfowl was killed in hunting seasons or found dead in Champagne-Ardenne region, France, and autopsied with focus on schistosomes. Seven Anas platyrhynchos (mallards), one Ardea cinerea (grey heron) and two Cygnus olor (mute swans) were parasitized by Bilharziella. One C. olor was parasitized by Dendritobilharzia Depending on season and hosts, various morphological forms of Bilharziella suggesting several species were observed. The differences in male and female worms concerned the morphology of genital apparatus, the spination on suckers, the body size and proportions. However, the comparison of DNA sequences led to a conclusion that these forms belonged to one species, Bilharziella polonica (Kowalewski, 1895). The morphological features and the body sizes of our samples of Dendritobilharzia seemed to differ from the type species of D. pulverulenta (Braun, 1901). Nevertheless, molecular analysis confirmed identity. We hypothesize that the differences in Bilharziella and Dendritobilharzia might be linked to internal host factors (e.g. hormonal levels), and influenced by season, host, and worm age. The definition of the genera Bilharziella and Dendritobilharzia was amended