Neuroterus (Diplobius) floricola bisexual form

Hosts: Quercus douglasii

GALL. — A small, egg-shaped capsule in the ament. Monothalamous, rarely two or three more or less fused. A modified anther, each capsule egg-shaped, almost smooth, microscopically coriaceous, drying brownish yellow, averaging 1.5 by 0.7 mm.; thin-walled, entirely hollow. Scattered in the aments of Quercus Douglasii (fig. 23).

RANGE. — California: Three Rivers. Probably occurs thruout the range of Quercus Douglasii.

This gall appears very early in the spring, the adults probably emerging a short time after the buds open on the oak. The species probably has an alternate, agamic generation. It is so closely related to the other species of the sub- genus Diplobius that, as with them, the alternate should be a leaf vein or petiole swelling. As pointed out in the introduction to this paper, the monothalamous, precisely formed anther gall is not as specialized as it looks, but is the inevitable result of a simple proliferation of anther material.

Neuroterus floricola Kinsey.

Quercus douglasii
Flower galls
Fig 184. Hypertrophied filament. Late March.

Fig 184. Projected outline of a cotype gall from Three Rivers, Calif. on Q. douglasii. Length 1.7 mm. Not truncate at base like florulentus Weld # Not distinguished in the field from Dryocosmus gigas (Kinsey) on the same host.

Neuroterus floricola, new species

GALL. — A minute. egg--shaped capsule in the aments. Monothalamous. Each capsule ovate, somewhat elongate, more pointed apically; golden yellow brown, the surface finely pitted like leather; averaging 1.5 mm. long by 0.7 mm. wide; thin-walled, entirely hollow. Singly or two or three completely fused; showing clearly the origin from the anthers, sometimes incompletely furrowed, or with parts of anthers attached; on the aments of Quercus Douglasii.

RANGE. — California: Three Rivers. Probably occurs thruout the range of Quercus Douglasii.

A form on the flowers of the oak must have a short life history, with an alternate, probably agamic generation.

This tiny species is of especial interest because the gall so closely resembles that of Andricus gigas Kinsey, gigas galls differing mainly in being larger, averaging 2.0 mm. in length by 1.0 mm. wide. Gigas was obtained from the same oak, in the same faunal area. I also have gigas from the same flowers which gave this Neuroterus. Of course the two insects are very distinct, belonging to different genera, even if the name Andricus does not define a genus. Some other species of Cynipidae produce similar galls on the aments. Here is one of the few cases I know among cynipids producing distinct galls where the species and genus of the gall maker is not the primary factor in determining the type of the gall. The anther appears to have only certain possibilities for abnormal development; practically identical results are effected when the stimulus is supplied by either Andricus gigas or Neuroterus floricola. Galls of much the same type, altho clustered differently and of several different shapes, are effected by Andricus dubiosus (Fullaway), Andricus serricornis Kinsey, Neuroterus pallidus Bassett, and some other species. In fact, I do not now recall any species where any other sort of modification of the anther is produced. The diversity of these insects is great; it would appear to be the nature of the anther which restricts the type of modification.