[Kinsey distinguishes this species "Diastrophus kincaidii variety austrior new variety" from "Diastrophus kincaidii variety kincaidii" as follows]
These two varieties are about as similar as any two forms which I should call distinct. Both insects and galls share the similarity. The best single distinction between the insects is the nature of the foveae of the scutellum ; other characters are distinct mostly in their averages. The two have distinct ranges. This species is not so very different from Diastrophus nebulosus and D. turgidus of the eastern parts of the United States, and I am not entirely certain that all of these should not be considered varieties of one species.

GALL. [same description for both varieties] — Large, irregular stem swelling, Polythalamous, with a great many cells. Swelling rather abrupt, elongate, up to 60. mm. in length by 20. mm. in diameter; somewhat irregular, smoothed, covered with bark of normal color. Internally filled with mostly loose tissue in which the larval cells are densely crowded, the cells not separate, but almost separable, broadly oval, averaging 2. x 2.5 mm. On stems of Rubus parviflorus (acc. B. G. Thompson in Mus. Comp, Zool.), and R. nutkanus.

RANGE. — California: Point Arena (Fullaway) ; Alameda Co. (thru Riley) ; Mt. Tamalpais.

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

Reference: https://www.biodiversitylibrary.org/page/45387508#page/114/mode/1up