Phytoptus abnormis, n. sp.

Produces galls on the leaves of the American linden or basswood, Tilia americana, Linn.

The transverse striae of the abdomen number about 56. This mite differs from all the other Phytopti I have seen in that the abdomen, just before the terminal sucker, is noticeably enlarged. But few specimens have been examined, as they have been very rare. In many of the galls, comparatively large, elongate eggs occur, which probably belong to some larger mite which preys on the gall-mites.

The gall is top-shaped, expanding above and contracting towards the upper surface of the leaves into a neck. It measures .155 inch in height, and .100 inch in diameter. The walls are deeply infolded, sometimes giving rise to unequal lobes. The outer surface is smooth, green and devoid of hairs. The cavity of the gall is made unsymmetrical by the deeper impressions of the wall. The inside of the latter is slightly roughened by small folds, and is clothed with long aciculate, unicellular hairs. These galls occur sparingly on the leaves of large trees in open woods at Bloomington, Illinois.

- H Garman: (1883) The Phytopti and Other Injurious Plant Mites^©

Reference: https://www.biodiversitylibrary.org/item/51995#page/144/mode/1up