Holcaspis bassetti, n. sp.

Gall: The gall occurs, sometimes singly, but usually in clusters about the twigs. The cluster represented at Fig. 2 was composed of 30 of these galls closely crowded together. The galls resemble very much the galls of Holcaspis duricoria Bass (Cynips mamma Wal) (Fig 3). The galls are very much the shape that a thick waxy material would take if dropped on the twigs and then suddenly congealed, leaved stout, test-like projections standing out from each drop. The central cell is placed low in the gall and can usually be seen protruding when the latter is broken off. Some entomologists have thought this gall to be identical with Walsh's C. mamma, but I have examined a large number of both forms and find the following points of difference, which convince me that this, if not a new species, is certainly a well marked variety:

H bassetti as compared with H duricoria, is rather larger and more irregular in outline. The teat-like projection is much heavier and longer in proportion to the size of the gall and appears to be a drawn-out portion of the substance of the gall, while in duricoria it is a small, hard pointed projection much resembling a spine in many cases, and often almost entirely wanting. In bassetti the substance of the gall is more corky and easy to cut. The central cell, as before stated, is at the base of the gall, and when the latter is removed the point of the cell can usually be seen protruding below. Before the gall is detached the central cell is situated with its greatest diameter perpendicular to the limb at the point of attachment of the gall. In duricoria the cell is situated at the center of the gall; it never protrudes from below when the gall is detached; and it always has its greatest diameter parallel with the limb at the point of attachment of the gall. The central or larval cells are also differently shaped. In duricoria the cell is egg-shaped, while in bassetti the end towards the twig is somewhat pointed, so that the cell is very much the shape of a plump apple seed with the point rounded off.

- CP Gillette: (1888) A Study of the Cynipidae^©

Reference: https://www.biodiversitylibrary.org/page/13762219#page/225/mode/1up