HELOPHORUS ORIENTALIS (COLEOPTERA: HYDROPHILIDAE), A PARTHENOGENETIC WATER BEETLE FROM SIBERIA AND NORTH AMERICA, AND A BRITISH PLEISTOCENE FOSSIL

Abstract

AbstractThe Helophorus species recorded by McCorkle as H. brevipalpis Bedel, and by earlier workers as H. granularis (L.) is found, on examination of the types, to be H. orientalis Motschulsky, a species widespread in eastern Siberia.The types of H. orientalis are described, and a lectotype is designated. The type of H. sahlbergi Kuwert, a species synonymous with H. orienta’is, is also described. Further Siberian and North American material is described with reference to the type, and the means of distinguishing H. orientalis from H. granularis and H. brevipalpis are discussed.Fossil prothoraces from Pleistocene deposits at Brandon, Warwickshire and Great Billing, Northamptonshire, England, are referred to H. orientalis.The life histories of the three species are compared, and differences in the egg cocoons and larvae are illustrated. H. orientalis is shown by laboratory breeding to be parthenogenetic. In the other species no maleless populations are known, and although there is no proof that they cannot breed without males, this is considered very unlikely.The ecologies of the three species are discussed.