Male.—Similar to the female, but differing in the following respects; antennae 14-jointed, reddish or golden brown, joints 1 and 2 dorsally dark rufous to piceous, third joint curved; abdomen rufous to piceous, darker dorsally, almost black basally on the dorsal surface; areolet averaging larger than in the female; length, 2.5–3.2 mm.
Galls.—Terminal swellings of a stem (Figs. 3 to 5), more or less club-shaped and somewhat bent and twisted, the enlargements gradual from the stem, of greatest diameter at the summit. Very much like some galls of Aulacidea tumida. Averaging about 70 mm. long by 18 mm. in greatest diameter. Under the bark the plant tissue is twisted, resembling the trunk of a wind-beaten tree. Many leaf petioles or stems of flower clusters are grouped at the summit of the gall, their bases involved in the swelling. Internally the galls are filled with pith, scattered through which are many larval cells, each oval, averaging 3.5 × 2.5 mm. The cells are merely cavities in the pith, without a separable or even distinct tissue to form them (the cells are often lined with the cast pupal skins of the insects). On Lactuca or possibly Prenanthes (the dead stems not exactly determinable).
Range.—Massachusetts: Sharon.
Cotypes.—One hundred and four female, sixteen male, and six gall cotypes in the collections of The American Museum of Natural History, of the Museum of Comparative Zoology, of Mr. Lewis H. Weld, and in the author's collection. The adults were all bred from galls which I collected from a single cluster of plants.
The adults emerged from June 5 to 12, 1919, the eggs undoubtedly having been deposited in the young plant in the previous June, the pupae overwintering in the dry stems of the host plant. Almost all of the males emerged before any of the females appeared; after thirty-six hours the females began appearing and the resulting ratio was 84 per cent females to 16 per cent males. Two parasites were bred from the galls.
The adult of this species is somewhat like that of A. tumida, but annulata is readily distinguished by the key characters given at the beginning of the description.
The galls of annulata are not much different from some of those of A. tumida, although the adult is distinct. It is quite likely that there are many species in this, a primitive genus of the Cynipidæ, which are not yet known, being mistaken for other species with similar galls. These galls are simple swellings of the stems of herbaceous plants, with some proliferation of the pith-cells, but with the resulting deformations all so slight (comparatively) that the galls of different species are not distinguished as completely as are the galls of the higher cynipids.
Diastrophus tumefactus, new species
Plate XXI, Figures 10 and 11
