Cynips-Antron-Besbicus
Philonix-Atrusca-Acraspis
FIG. 7. KNOWN DISTRIBUTION, SUBGENERA OF CYNIPS
Base from Goode series of Base Maps, by permission University of Chicago Press.
The primary subdivision of the genus into one group that is all but exclusively Eurasian and Pacific American, and into a second group that is confined to North America east of the Sierra Nevada, should have occurred near the center of the origin of the genus. We may hypothesize this center in the southwestern United States or in adjacent areas of northern Mexico. From here the first subgeneric group could have moved westward to the Pacific Coast where Antron and Besbicus were isolated, and by way of Alaska and Siberia into Asia and Europe where the subgenus Cynips developed. The second group, differentiated into the subgenera Philonix,