Morphology and biology of trematodes (Gigantobilharzia acotylea), parasites of puddle ducks and gulls in Uzbekistan.

Morphological-biological traits of the trematode, Gigantobilharzia acotylea Odhner 1910, at all stages of ontogeny were studied. Mollusks (Physafontinalis and Anisus spirorbis) that are widespread in waterbodies oft he Syrdarya River basin were found to be intermediate hosts of this trematode under natural and experimental conditions of Uzbekistan. The total infection of mollusks by Gigantobilharzia parthenitae and cercariae R.,ached 0.5 and 0.3% in Ph.fontinalis and A spirorbis, respectively. In experimental conditions, 100% of these mollusks were infected. The time of cercariae maturation in intermediate hosts ranges from 23 to 44 days depending on temperature. The cercariae actively penetrate through the skin of birds and reach maturity in 30-35 days. Then, females and males start breeding. A complex of specific features of various developmental stages, in particular cercariae, for the differentiation of the species is suggested on the basis of the analysis of morpho-biological peculiarities of these trematodes.