Page:The Gall Wasp Genus Cynips.pdf/36

 (Q. dumosa, Q. durata, etc.) and down in the valleys, on the Valley white oak (Q. lobata) there are numerous long-winged species, echinus (fig. 163), schulthessae, etc., which everyone will accept as typical Cynips of the subgenus Antron. But galls of schulthessae (figs. 151-153) and patelloides (figs. 144145) are remarkably close, with similarities in internal structural details (figs. 192-193) which are infallible indicators of close relationships. The form of internal structure here involved is known nowhere else but in the subgenus Antron. Such gall structures, as well as the adjacent distributions of these species on related oaks, lead us to believe that guadaloupensis and schulthessae are close relatives in spite of their differences in wing characters.

There are a couple of cases of gall identities so thoroly guaranteeing the affinities of dissimilar insects that the systematists have already accepted them. These galls are the large, spherical, thin-shelled oak apples (figs. 262-263) which occur on the leaves of several species of white oaks in the Southwest. There are two stocks, Cynips dugèsi and Cynips bella, with seven described species in the area. The galls of all seven are identical, prolonged studies having failed to show any constant distinctions among them. One may collect galls from the foothills of southern Colorado or the mountains of northern New Mexico and Arizona or from West Texas into southern New Mexico and Arizona and into Central Mexico without finding evidence of more than one species. But upon breeding insects from these galls, each area is found to have distinct species, with fully winged insects in only a few of these areas. Three of the seven insects have wings which are from 15 to 37 per cent shorter than the normal for the subgenus. Weld (1926:18–19) recognized that the species brevipennata with shortened wings “replaced” a fully winged species in the more northern portion of the Southwest, but the contribution which these species offer to the problem of the origin of species needs further emphasis.

The original concept of Acraspis was based on the well-known, short-winged species pezomachoides and erinacei (fig. 3) of the eastern United States. All of the close relatives of pezomachoides are similarly short-winged insects in the agamic generation; but ever since Triggerson's studies (1914) of the life history of Cynips pezomachoides erinacei we should