1979] 
North & Shaw — Pterophylla camellifolia 
369 
The ranges of population means for the distance from the frons to 
the distal end of the tegmina (western: 38.3-44.7 mm; northern: 
37.4-39.7 mm), frons to distal end of subgenital plate (western: 
35.7- 38.6 mm; northern: 31.7-33.7 mm), tegminal length (western: 
32.8- 37.9 mm; northern: 31.4-33.7 mm), metathoracic femoral 
length (western: 17.9-20.6 mm; northern: 13.0-15.1 mm), and tegmi¬ 
nal width (western: 13.7-15.1; northern: 13.0-15.1), indicate that 
western katydids are on the average larger than northern katydids 
(North 1978). 
Discussion 
Iowa is the northwestern limit of the range of P. camellifolia. The 
distribution of oak-hickory forests, even in presettlement times, elim¬ 
inates the availability of much of the western and northern part of the 
state (Fig. 1). Approximately 75% of the 6.5 million acres of wood¬ 
land that greeted the state’s first white settlers in the 1850’s has been 
destroyed, leaving a sparse 1.6 million acres. Temperature also may 
be an important factor in limiting the northward extension of P. 
camellifolia south of available oak-hickory forest (Fig. 1). The same 
factors appear to affect the distribution of 17-year cicadas whose 
northern limits in Iowa mimic those of P. camellifolia even though 
suitable habitat is also available for range expansion of this species 
(Lloyd and Dybas 1966). 
At the time of the original land survey in Iowa territory, the native 
vegetation was of two main types, prairie and deciduous forest. More 
than three-quarters of the state was open grassland and the remainder 
oak-hickory forest (Simonson et al. 1952). Since Caucasians arrived 
in Iowa, the removal of timber has been extensive. It is possible that 
in presettlement times P. camellifolia was more or less continuously 
distributed across eastern and southern Iowa. However, our failure 
to find any colonies between southwest and central Iowa (Fig. 1) 
argues against such a continuous distribution. 
The western and northern populations of P. camellifolia may have 
differentiated during the Pleistocene. Deevey (1949) concluded that 
glacial chilling was so extensive that many species of plants and 
animals could have survived only in peninsular Florida and in Mex¬ 
ico. The existence of four or more populations of P. camellifolia in 
the eastern half of the United States (Hebard 1941, Alexander 1968, 
Shaw and Carlson 1969), as well as dispersion by flightless females 
argues against only these two glacial refugia. 
