Pleistocene Helophorus (coleoptera, hydrophilidae) from Borislav and Starunia in the Western Ukraine, with a reinterpretation of M. Łomnicki´s species, description of a new Siberian species, and comparison with British weichselian faunas

Abstract

The five Helophorus species described by Łomnicki (1894) from fossils in oil-impregnated Pleistocene silts at Borislav, near Lvov, are redescribed and indentified as modern species. Four of Lomnicki’s names fall into synonymy, but the fifth, H. praenanus , replaces H. jacutus Poppius for an eastern Siberian species. The fossil Helophorus collected along with the Woolly Rhinoceros by the University of Krakow expedition to Starunia in 1929 are identified, and nine species, all still extant, are present in the sample. These include four species which today live over much of Europe, two which are exclusively eastern Siberian, one found in both eastern Siberia and arctic North America, and two which are widely distributed over Siberia and extend into northern Europe and North America. It is concluded that the climate at Starunia during the period when the deposit was laid down was colder and more continental than at present, but it is stressed that since the assemblage of species found as fossils at Starunia does not exist in any one place today, there may be no exact modern climatic equivalent to Pleistocene Starunia. The Starunia Helophorus fauna is compared with the O rthoptera as described by Zeuner (1934). In both cases there is a mixture of European and Siberian species, but the O rthoptera differ from the Helophorus in including a num ber of montane species. Neither group contains any species today found only in the high arctic. The Starunia deposit has been 14 C dated at about 23000 years B.P., and its fauna is compared with British faunas from the same general period of the last glaciation. The faunas are broadly similar, but the Starunia fauna shows evidence of greater dampness perhaps associated with the period of maximum Weichselian glacierization. The Siberian Helophorus formerly included in H. hrevipalpis Bedel, present in both the Starunia sample and British deposits, is shown to be a distinct species, and is described as H. aspericollis , sp.nov.