Dugesia lugubris (Tricladida: Paludicola), a European Immigrant into North American Fresh Waters

Abstract

Dugesia lugubris (Schmidt), a Palaearctic freshwater triclad, is described from North America. A morphological and taxonomic evaluation is presented and comparisons with European material and data are made, confirming the initial diagnosis. The known distribution of the species in North America is discussed in relation to what is known of its distribution and ecology in Europe, and it is concluded that the introduction is probably unique and of recent occurrence. It represents the second authenticated case of passive dispersal by man in the freshwater Tricladida, and is almost certainly a result of the shipping plying between the St. Lawrence River and various European ports. The present findings in no way conflict with the opinions of modern American taxonomists that early records of D. lugubris in North America are the results of mis-identification of Cura foremanii (Girard). A key for the separation of these two superficially similar species is provided.