Cynipidae

Andricus

Quercus alba

Alabama

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Quercus bicolor

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Quercus chapmanii

Quercus macrocarpa

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Quercus margaretiae

Quercus michauxii

Quercus oglethorpensis

Quercus stellata

Cynipid galls of the eastern United States

Andricus pisiformis (agamic)

Andricus pisiformis sp. nov.

Gall.--On the terminal twigs of white oak (Quercus alba) and post oak (Quercus minor [stellata]) from the middle of May to early in June. Monothalamous. Spherical or pea-like. Milky white or pale greenish white, speckled and marbled with green or lilac. Fleshy when fresh, hard and woody when old and dry. It is hollow inside with no separate larval chamber. It is evidently a bud gall. Diameter 3-6 mm.

Habitat.--NJ, MA

The flies mature in the gall during the latter part of September and in October, but do not emerge until the following spring. The gall is a pretty object and looks like a very small marble. 

Descriptions of New Species of Cynipidae

Andricus pisiformis

Quercus alba, bicolor, chapmani, macrocarpa, stellata
Bud galls 
Globular, 3-6 mm, white, mottled, outer wall fleshy, inner hard and brittle. Early spring. Dropping when mature in April.

[Photo caption]
On Q alba. Photos: single galls, the inner structure, deformed by guests. Also on Q bicolor, macrocarpa, chapmani, stellata, margaretta. They drop in April. Adults emerged the next Mar 24-26; second spring Apr 6 and third spring Mar 29.


Andricus pisiformis (Beutenmueller 1911)

Hosts: Quercus chapmanii

[Asexual generation bud gall found in the spring]

Using gall wasps on oaks to test broad ecological concepts

Quercus michauxii added tentatively as a host based on [this unconfirmed observation](https://www.inaturalist.org/observations/111027591). 

Quercus oglethorpensis added tentatively as a host based on [this unconfirmed observation](https://www.inaturalist.org/observations/155144801). 


[Neuroterus vesicula](https://www.gallformers.org/gall/840) and [Andricus pisiformis](https://www.gallformers.org/gall/841) are both small, globular, often dark-surfaced bud galls found on white-group oaks in the spring. Based on the photos Weld provides of Andricus pisiformis, that species is distinguished by many prominent, near-circular, white-colored spots. According to Scott Digweed (personal communication) galls with that appearance on Quercus macrocarpa have been found to contain adults matching N vesicula. 

Adults reared from galls on Quercus stellata initially identified as A pisiformis due to the presence of spots were found to match N vesicula. However, on further examination, the spots on these galls (and many others on Q stellata) were seen to be somewhat distinct from those on A pisiformis. The spots on these galls are smaller, more irregular in shape and often less clearly bounded, with networks of lighter-colored cracks extending from spots, sometimes connecting many of them.

Aside from gall appearance, according to the literature, A pisiformis adults emerge up to a year after the appearance of the gall, while N vesicula adults emerge the same spring. A pisiformis is also easily distinguished by cross section. It contains a hard internal larval cell surrounded by a soft, fleshy external shell. 

Adults determined to be A pisiformis by adult anatomy were found to be very distinct from N vesicula in UCE genetic analysis by [Ward et al](https://www.biorxiv.org/content/biorxiv/early/2022/02/13/2022.02.11.480154.full.pdf).

Gallformers ID Notes