GEOGRAPHIC DISTRIBUTION AND BIOGEOGRAPHY OF REPRESENTATIVE SPECIES OF XERIC GRASSLAND-ADAPTED NEARCTIC LYGAEIDAE IN WESTERN NORTH AMERICA (INSECTA: HETEROPTERA)

This paper outlines the known distribution of eight xeric grassland-adapted species of Lygaeidae, and examines these distributions with respect to the glacial history of North America during the Pleistocene, and past and present distribution of grassland vegetation. Four of these species ( Neosuris castanea , Sisamnes claviger , Ligyrocoris latimarginatus , and Melanopleurus perplexus ) probably survived the Pleistocene in refugia south of the Late Wisconsinan ice sheet. Differences in climatic requirements may explain the variations in geographic distribution exhibited by these four insects and a methodology for testing this is discussed. The four other species ( Crophius ramosus , Kolenetrus plenus , Slaterobius insignis , and Emblethis vicarius ) may have occurred in the north prior to 1.2 mya and survived the Late Pleistocene in both the northern Beringian refugium and in southern refugia. Molecular systematics, especially use of DNA restriction site or sequence data, might provide the evidence needed to test historical biogeographic postulates based on the extant distribution of these species.