Studies on Cercaria szidati sp. nov., a New Furcocercous Cercaria of the Vivax Type

Abstract

A new longifurcous, pharyngeate cercaria of the Vivax type has been found to develop in Campeloma sp. collected from the Tippecanoe River, near Lafayette, Indiana. Although about fifteen species of Vivax larvae have been described, C. kentuckiensis Cable, 1935, has been the only fresh water representative of the group reported from the United States. Cable (1938) extended his brief description of this species and gave a comprehensive review of the group in a paper to which the reader is referred. The present species is named in honor of Professor L. Szidat who found a very similar cercaria in East Prussia and determined it to be the larva of Linstowiella viviparae (von Linstow, 1877). Snails were collected during the summers of 1942-43 and examined for emerging cercariae which were studied alive, both unstained and with the aid of supra-vital dyes. Measurements were taken from larvae killed in hot 10% formalin because living cercariae were so active that they could not be measured without excessive cover-glass pressure. A few infected mollusks were crushed to obtain sporocysts and observe the development of cercariae. This investigation was carried out under the direction of Dr. R. M. Cable, whom I wish to thank for his interest, criticism, and suggestions.