The life cycle ofParvatrema homoeotecnumsp.nov.(Trematoda: Digenea) and a review of the family Gymnophallidae Morozov, 1955

Abstract

1.Parvatrema homoeotecnumsp.nov. from the oystercatcher,Haematopus ostralegus occidentalisNeumann at Aberystwyth is described and compared with other species of the genus.2. The life cycle of this species is unique. The larval stages occur in the gastropod,Littorina saxatilis(Olivi) subsp.tenebrosa(Montagu) and include germinal sacs which have a structure and development similar to an adult digenean. There are no free-living stages and only one intermediate host.3. The significance of this unique life cycle is discussed.4. The family Gymnophallidae Morozov, 1955, is reviewed. Emended definitions are given for the family, subfamilies and genera. Keys, diagnostic features and brief notes of the species are included.I am very grateful to Dr Gwendolen Rees, who suggested the investigation which led to the discovery of this species, for her advice and indispensable assistance throughout the work and the preparation of this paper. I am also grateful to the late Professor T. A. Stephenson for his interest and for the provision of working facilities; to Mr W. A. Ballantine, Mr A. H. Clarke, Jr., Mr C. Curtis, Miss G. P. F. Evans, Dr V. Fretter, Professor L. A. Harvey, Mr D. H. Jones and Dr J. Lewis who sent me specimens ofLittorina saxatilis; to Professor R. M. Cable and Emerit. Professor G. R. La Rue for helpful suggestions; to Mr J. R. Hirst and Mr D. Hemingway Jones for photographic and technical assistance and to the Department of Scientific and Industrial Research for a grant which made the work possible.