372 
Psyche 
[December 
northern populations of this species. Examination of subgenital 
plates and cereal arms of 12 specimens from Anderson County, 
Kansas, indicate they are western P. camellifolia. This would support 
Kansas as a possible glacial refuge and site of differentiation of 
western P. camellifolia. 
Postglacial northern migration of oak-hickory forests with their 
accompanying fauna along the rivers of the Missouri and Mississippi 
drainage systems would have facilitated contact between western and 
northern katydids. Forest continuity in southern Iowa could have 
allowed the western population to cross from the Missouri to the 
Mississippi drainage system. During the Climatic Optimum Period 
(warm, moist period from approximately 6000-8000 B.P.), decidu¬ 
ous forest occurred more continuously and at slightly higher latitudes 
than at present (Smith 1957). Southward and eastward shrinking of 
the ranges of fauna and flora may have occurred during the warm and 
dry Hypsithermal (= Xerothermic Interval, ca. 4000-6000 B.P.) 
(Smith 1957). On the basis of the Climatic Optimum Period and 
boreal relicts, Smith argues for gallery forests or “islands” of forests 
along the major rivers as refugia for mesic-forest-inhabiting animals 
during this period. Although the drier-loving oak-hickory forests 
may have at first advanced during this period, they probably receded 
later and again may have remained only as gallery forests along 
rivers. 
Assuming that the western and northern populations had come 
together during the Climatic Optimum Period, their present distribu¬ 
tion could be explained by the effects of the Hypsithermal. The 
western and northern populations occur along or near river systems 
where they could have escaped the extreme conditions of the Hyp¬ 
sithermal. This could explain the existence of both western and 
northern populations within the Wisconsin drift area (Fig. 1), an area 
which contains protected ravines created by the actions of the Wis¬ 
consin glacier. The main bodies of these two populations could have 
been pushed southwestward and east-southeastward. The 150-200 
km gaps between the southwestern and central colonies of western 
katydids and the eastern and central colonies of northern katydids 
could simply be the result of lack of forest and/or time to renew 
contact. 
The fragmentation of animal ranges resulting from the activities of 
civilized man throughout his historic period has resulted in many 
