Cynips (Acraspis) nubila
agamic forms
GALL. — A mass of coarse hairs, containing a spherical, hard core. Monothalamous, the core averaging 4.0 to 7.0 mm., the entire gall averaging 10.0 to 15.0 mm., compacted clusters of several galls measuring up to 24.0 mm. in diameter. The central core strictly spherical except where drawn out basally at the point of attachment; the surface of the core crystalline, very rough, scurfy, covered with short, straw-colored, crystalline hairs among which are the close-set, long, fine, hair-like spines which form the tangled, woolly covering of the gall, these spines up to 8.0 mm. in length, unbranched, wavy. The central core hard, crystalline, brittle, with an outer wall fully 1.0 mm. in thickness; all of the rest of the core (up to 5.0 mm. in diameter) is hollow, the inner walls being rough, irregular, without any other larval cell. Occurring singly or, more often, in clusters of two to five galls, the clusters usually more or less hemispherical but sometimes more elongate when containing several galls; attached to the mid-veins, on the under surfaces of the leaves of Quercus arizonica, Q. oblongifolia, Q. Toumeyi, Q. reticulata, Q. glaucophylla) , and probably other related oaks.
RANGE. — Known from Arizona and central Mexico. Probably widespread in Mexico, and to be expected in southwestern New Mexico. Figure 58.
The gall of this species is one of the most attractive in the genus Cynips. The tangled mass of brilliantly colored, hair- like spines covering the spherical core marks the gall at some distance in the field. In collecting in January (1920) in the Santa Rita Mountains of southern Arizona, I camped at four thousand feet among trees on which nubila galls were common. A mountain storm had banked these evergreen oaks with wet snow, offering a background against which the wine-purple galls appeared too fantastic to be real anywhere but in the enchanted lands of our Southwest.
The galls of the Arizona varieties probably appear early in the summer; they are full-grown by September, and the adults probably mature in another month or so. The insects, however, do not emerge until late in December or in January, during a season of cold weather and snow. Perhaps the more southern, Mexican variety, incompta, has a different life history.
While nubila is common in Arizona south of Globe, it has not yet been recorded from north of there or from New Mexico. If must be very rare in these latter regions if it occurs in them at all.
While the hairy gall of this species appears superficially different enough from the galls of most Cynips, it is nothing but a villosa gall with the spines much lengthened. The spines are inserted on the surfaces of the two in the same way, in two varieties of nubila they are enlarged basally, quite as they are in villosa, and in both species they are surrounded basally by peculiar, short, crystalline hairs. The resemblances are so striking that, once having seen them, one wonders why they are not apparent at first glance.
[Kinsey describes three varieties of this species; only Andricus incomptus is listed separately. See paper for details on the other two.]
