NOTES ON THE LIFE-CYCLE OF AZYGIA ACUMINATA GOLD-BERGER, 1911 (AZYGIIDAE-TREMATODA) DONALD M. WOOTTON 1 Marine Biological Laboratory, Woods Hole, Mass. Studies of trematodes belonging to the genus Asygia Looss, 1899 from North American fresh-water fish, date from the work of Leidy (1851). He described Distoma longum from the stomach of Esox ester LeSueur, 1818 from near Cleve-land, Ohio. Since that time many workers have added to knowledge of the North American species belonging to this genus. Manter (1926) gave a systematic re-view of the family Azygiidae and stated (p. 57) that "Azygia is the only genus of the family showing taxonomic confusion in its species." He further pointed out that these forms are all very muscular and highly contractile, which not only alters the general shape of the worm but also changes the relative position of such struc-tures as the acetabulum and the reproductive organs. He also mentioned that size of the eggs and distribution of the vitellaria vary considerably within a species and cannot be relied on as taxonomic characters. Manter recognized three valid North American species: A. acuminata Goldberger, 1911, A. angusticauda (Stafford, 1904) and A. longa (Leidy, 1851). Van Cleave and Mueller (1934) endorsed the action of Manter in reducing the number of species in North America and felt that A. acuminata should also be re-duced to synonymy with A. longa. Stunkard (1956) gave a chronological account of the genus Asygia and noted (p. 266) " discordant observations and divergent opinions," concerning the pro-posed specific and generic names for members of the genus. This thorough ac-count need not be repeated here. Stunkard recognized A. sebago as a distinct spe-cies and suggested that the European A. lucii may also be present in North Amer-ica and that it possibly is distinct from A. longa. None of the species have been studied to determine the extent of variation that normally occurs as the result of early development in a wide variety of paratenic hosts (small fishes and planarians) and further development in varied definitive hosts (large fishes). Until such studies are undertaken, the taxonomic picture of the group will remain confused. It is evident, in reviewing the literature, that species proposed by various North American authors and since placed in synonymy may indeed be valid species. In such worms, which are very muscular and highly contractile, size and shape can not be relied on as taxonomic characters except in a very general way. The fact that these worms become sexually mature while relatively small and continue to grow throughout life further complicates the taxonomic picture. A. angusticauda is the only North American species which can be readily distinguished from the other species described from this continent. It can be separated because of the more 1 Present address : Chico State College, Chico, California. 488
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