Neuroterus (Diplobius) howertoni, agamic form

Neuroterus howertoni

Gall. A small, eruptive swelling on the under surface of the leaf blade. Each “monothalamous’’, up to 1.5 mm. in diameter. The larval cell closely imbedded in the leaf, without a distinct wall, the gall evident on the upper surface only by a very slight, papilla-like swelling, colored more yellowish or brown than the leaf blade; on the under surface forming a more distinct, cone-shaped swelling with a central depression, resembling a “volcano” cone; more often leaf color on the under surface, and not pubescent except with the microscopic pubescence normal to the leaf. In numbers on each leaf, on Quercus virginiana and other live oaks (figs. 37, 38).

RANGE. — New Mexico (Bassett). Texas: Austin, Leander, Skidmore, Hondo. Possibly distinct varieties occur in the two states.

This is practically a physiologic species, for the insect is not satisfactorily distinct from niger or verrucarum, differing in a few characters which appear only of varietal impor- tance in this portion of the genus. The galls, altho quite suggestive of niger are so distinct that they ought to be considered a separate species, especially since the same oaks over the same region bear typical niger galls. In a similar situation with Neuroterus verrucarum pulvinus I gave only varietal rank to the physiologic group, but we as yet have so little insect material of howertoni that I do not feel warranted in too definite an opinion as to relationships.

Bassett’s type material was from an undetermined oak, which it would now appear was Q. grisea. The distinct host, Q. virginiana, from which my material came, may isolate a distinct variety, and the two faunal areas involved may further effect isolation, but altho I have insects from all three of the Texas localities, they are not sufficient for varietal studies. My galls contained larvae in the first half of December and gave adults at some later date, probably in early spring. Dr. Patterson has cut adults from galls in the last of December. As Bassett stated, the insects emerge from the lower surfaces of the galls, but the normal, central depression should not be mistaken for an exit hole.

- Alfred Kinsey: (1923) The Gall Wasp Genus Neuroterus^©

Reference: https://www.biodiversitylibrary.org/page/53512324#page/295/mode/1up