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Which gall is this? - Andricus brunneus

Which gall is this? - Andricus brunneus
Escondido, San Diego County, California, USA
January 8, 2014
Growing from mid rib on underside of Coast Live Oak (I believe) leaf.

Images of this individual: tag all
Which gall is this? - Andricus brunneus Which gall is this? - Andricus brunneus Which gall is this? - Andricus brunneus

Moved from Unidentified Galls.

oak ID
Can you double-check the oak ID? It looks as if it may be Q. berberidifolia (or maybe Q. cornelius-mulleri, but not sure if the Q c-m range extends into Escondido). It doesn't look like Q. agrifolia. The gall ID depends on the host species. Also I don't know of a gall like this on Q. agrifolia.

If you post photos of some entire oak leaves, both sides, I could probably ID them. If you find any acorns too (that you're sure came from this tree), that would be a bonus.

Hi Joyce
Good to know I can post images of the host plant. This is the most pulled back image I have. I can't recall where at Daley Ranch I spotted this gall in January but I'll be sure to capture more data the next gall I find :)

white oak
Your third photo confirms my suspicion of "scrub" oak. I looked at a Daley Ranch plant list. It lists Quercus x acutidens, which is a hybrid of Quercus cornelius-mulleri and Quercus engelmannii and must be what this is. If I had seen this tree/shrub I likely would have guessed just Quercus cornelius-mulleri (or Q. berberidifolia; they are closely related, look similar, and have somewhat different distributions). I don't pretend to understand hybrids.

At any rate, the key detail in terms of the gall is that this is a white oak (all the oaks just mentioned are white oaks, whereas Q. agrifolia is a black oak). So based on that, the wasp that created the gall should be Andricus brunneus, which only occurs on white oaks. It looks as if this gall might have been parasitized -- it's got some damage on it and doesn't look as robust as they can look.

Thank you Joyce
Great information!

Moved from ID Request.

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