Trigonaspis ornata, new species

GALL. — Spindle-shaped, covered with a golden brown mass of short filaments; 6. mm. wide by 11. mm. long, widest slightly above the middle; distinctly tipped apically. Covered with a densely compacted mass of filaments, each filament short, wholly flattened with a slender, narrow blade 2. mm. long, the tips purplish when fresh. The central stem is swollen to form a thin-walled, empty larval chamber, apparently monothalamous. A bud gall, or on leaves, attached to the end of the mid-rib; on Quercus breviloba.

RANGE.— Texas: Austin (Patterson).

The galls were collected March 3, and adults emerged April 15. In this country the genus has been known previously only from root galls, tho in Europe it is obtained from leaf and stem galls also.

The galls superficially resemble those of Neuroterus evanescens Kinsey, described in this paper, but the anthers in that gall are not particularly modified. The adult of this species closely resembles Trigonaspis radicola (Ashmead); the female of ornata differs in being more brilliant rufous in color, slightly smaller, the antennae are distinctly more slender, the scutellum is less rugose with the basal depression smooth (rugose in radicola), and the wing veins are much heavier, even the cubitus being heavy (quite faint in radicola). A further study of material from more localities and hosts may show that this is a variety of radicola, which occurs on Q. alba, and was first described from Missouri. Ornata will prove a distinct variety at least.

The connection of ornata and radicola prompts a suggestion concerning the life history of the species, which though resting on circumstantial evidence, may be hazarded if it is taken only as an hypothesis. Brodie (1896, Ann. Rpt. Clerk Board Forestry, Ont., pp. 114-116) records Biorhiza forticornis ovipositing on the rootlets of Q. alba. In a 1920 paper (Bull. Amer. Mus. Nat. Hist., XLII, p. 374), I recorded the observation of Biorhiza forticornis (which is wingless, agamic, coming from terminal twig galls on Q. alba) ovipositing in December at the roots of Q. alba. I have observed galls of Trigonaspis radicola on the roots of trees which bore old galls of forticornis, and recently Weld (Proc. U. S. Nat. Mus., LIX, pp. 203-204) notes thirty-six instances of coincidence of the two galls on trees of Q. alba. There is considerable circumstantial evidence, then, of the cyclic alternation of Biorhiza forticornis and Trigonaspis radicola. In the paper above mentioned I further described a March brood of forticornis, obtained from the same galls as the December brood, ovipositing in the terminal buds of the tree; no galls were obtained from these buds in the experiments. Is it possible that the ornata gall (or more probably a similar variety on Q. alba) is the bud gall from eggs of the March brood of forticornis Are there two interlocking cycles in the life of this species? What is the solution of the heredity questions presented? Such are the alluring problems to be solved only after the cycle has been experimentally investigated.

- Alfred Charles Kinsey: (1922) Studies of some new and described Cynipidae (Hymenoptera)^©

Reference: https://www.biodiversitylibrary.org/page/45387508#page/201/mode/1up