Grahamstoneia humboldti (agamic)

Grahamstoneia humboldti, sp. nov.

Hosts: Quercus vacciniifolia, chrysolepis

Diagnosis: The gall somewhat resembles that of Andricus projectus Weld, 1952b although is more slender and green when young rather than red. However, morphologically the adults are very different.

Gall. (Fig 12). A bud gall on terminal or axillary buds, up to 8mm long and 2–3mm in diameter. Smooth conical gall with a pointed tip, emerging from bud scales. Young galls are green with a slight pubescence at base that rubs off easily; mature galls are a rich dark brown colour. 

Biology. Only the asexual generation is known, which induces galls on Q. vacciniifolia and Q. chrysolepis within Quercus section Protobalanus – the golden cup or intermediate oaks (Denk et al. 2017, Govaerts & Frodin 1998). Mature galls were collected in early November, and adults emerged soon afterwards.

Distribution. USA: California (three locations: Berry summit, ~25km E of Arcata; a site 30km NE of Arnold; and Irvine Lodge rest area on route 101, ~20km N of Willits); Arizona (Oak Creek Canyon, 15km N of Sedona).

A new genus of Nearctic oak gall wasp, Grahamstoneia Melika & Nicholls, gen. nov. (Hymenoptera: Cynipidae, Cynipini)