Cynips quercus cornigera n. sp. (as yet unknown) [ie gall named without an adult wasp specimen]

Quercus palustris Pin oak.

Woody knots on the limbs, emitting pale yellow, conical, brittle projections.

Of all excrescences on oaks in general, the present one, wherever it occurs, is perhaps the most conspicuous, as by its abundance it deforms the tree and seems to cause considerable injury. It consists of woody knots on the limbs, looking usually as if many of them were closely packed together and thus forming an oblong, woody irregular mass, sometimes two inches or more long. Its most striking character are its slightly curved conical projections, hollow on the inside, which bud forth from all sides of the gall. On dry, dead galls, these horn shaped projections are for the most part broken off, so that their bases alone are visible, projecting like short tubes from the cracks of the woody tubercle.

After having very frequently observed dead galls of this kind, I finally succeeded on the 13th of May, 1862, to find some young and growing ones. They were of moderate size; their back was greenish and their wood soft and succulent. The conical projections were just beginning to bud forth; when laid bare, by removing with a knife the wood around them, they appeared to extend deep inside of the gall, almost down to the twig. Their color was whitish, their consistency soft, apparently fibrous, and not woody. At that time, they were not hollow yet, and I could not find any larvae in them. When I visited the same spot during the latter part of June, I found some of the horn-shaped bodies already projecting about one-tenth of an inch; their substance had become harder and more woody; their inner end had become club-shaped, distinctly isolated from the surrounding wood, so that the whole of these bodies could be easily removed by cutting away the wood around them. On the inside, the inner end was hollow and contained a small larva.

- Baron Osten Sacken: (1862) Additions and corrections to the paper entitled "On the Cynipidae of the North American Oaks and their Galls"^©

Reference: https://www.biodiversitylibrary.org/item/22852#page/293/mode/1up