Pachypsylla celtidis-globulus n. sp.

A gall on the upper side of the leaf represented by a very circular hole with vertical walls near the top and widening internally; the rim is not thickened, but is vertically elevated above the leaf surface around the opening. The walls and bottom of the excavation are without decided sculpture and of a lighter color than the leaf; the elevated rim is of the same color as and not thicker than the leaf. Average diameter 1.75 mm. On the under side of the leaf the gall is globular or slightly more pyriform and almost stylate, or slightly more flattened and more sessile. There is a larger or smaller shallow apical depression without central nipple, but sometimes limited by a raised rim. Surface a little shining, finely rugose and not pubescent, rarely furnished with a solitary hair. Average diameter 3.3 mm. I have only a single leaf covered with these galls received from Columbia, S. C, collected in the month of September. No imago has been reared therefrom. This is at once distinguished from the preceding species by the very deep vertical impression on the upper side of the leaf and its globular smooth form on the under side of the leaf.

- CV Riley: (1890) Insects injurious to the hackberry^©

Reference: https://www.biodiversitylibrary.org/item/42358#page/635/mode/1up