Cynips pezomachoides
agamic forms

[Kinsey treats Acraspis erinacei as a variety of pezomachoides, and the presence or absence of spines is not diagnostic for most of his varieties. The description below may not apply fully to pezomachoides if erinacei is excluded.]

GALL OF AGAMIC FORMS. — Small to moderately large, spherical to ellipsoid, naked and faceted to spiny. Monothalamous or agglomerate or polythalamous with 2 to 8 cells. More nearly spherical galls usually smaller, occasionally larger, up to 7.5 mm. in diameter; these galls usually with one or at the most two cells. The polythalamous galls more ellipsoid, occasionally showing lines of fusion of two or more smaller galls; up to 20.0 mm. in length. The surfaces of the galls closely set with broad, polyhedral bodies, giving a faceted appearance, these without spiny tips or with short, spiny tips, or with long and flexuous tips, the galls in consequence varying from entirely naked to roughly faceted to densely spiny. Young galls light green and rose-tinged, the spines (if present) often brilliant purplish red; the older galls be- coming straw yellow to brown and darker, the spines (if present) be- coming dark purple. Internally compact crystalline; the walls thick, flexible when moist, very hard when dry; the larval cavity without a distinctive cell wall, the cavity central if single, the cavities side by side if there are two, the alignment somewhat irregular if there are more than two. Attached to the midveins or lateral veins or on the petioles; on either the upper or under sides of the leaves of the true white oaks (known from Quercus alba, Q. bicolor, and Q. Gambelii).

[Kinsey goes on to describe 8 agamic varieties of pezomachoides:

cincturata, known from wasps collected in Colorado but no gall, tentatively associated with Quercus gambelii

ozark, known from galls ranging from naked to spiny on Quercus alba in OH, WV, IN, IL, KY, MO, AR

wheeleri, known from galls ranging from naked to spiny on Quercus alba in NH, MA, PA, OH, MD, WV, MI, IN, IL, MO, VA, KY, TN, NC, GA

pezomachoides, known from galls lacking spines on Quercus alba in NH, MA, CT, NY, NJ, PA, MD, DC, VA,NC, SC, TN, GA, AL, FL

derivatus, known from galls lacking spines on Quercus alba in PA, OH, WV, IN, IL, KY, TN, SC, GA, AL

erinacei, known from galls either naked or spiny on Quercus alba, covering the northern midwest to New England

advena, known from naked to spiny galls on Quercus alba in KY, TN, NC, SC, GA

echinoides, known from spiny galls on Quercus bicolor--likely a mistake, see ID Notes for Acraspis echini]

- Alfred Charles Kinsey: (1929) The Gall Wasp Genus Cynips^©

Reference: https://www.biodiversitylibrary.org/page/53516882#page/374/mode/1up