Tree and gall for i.d.

[2dogs2000]

I think the tree is maple and I am wondering if the gall could be the beginning of nail gall fungus? Can someone confirm or correct me in my id's?
The photos were taken 29/07/2011

[Kayleigh]

cant help but I know a man who can...

The Wildlife Trust for Bedfordshire, Cambridgeshire, Northamptonshire and Peterborough - Events

[Hawk Roosting]

Certainly looks like field maple, but the galls are caused by a specie of eriophyid mite, not by a fungus.

I always think the galls on lime caused by Eriophyes tiliae are pretty spectacular, bright red/pink.

[Dorts]

It's one of the Field Maple Galls caused by either - Aceria aceriscampestris or A. macrochelus .
Probably the former, as the latter has tiny hairs sticking out of the round gall, which I don't see.
Dorts.

[2dogs2000]

Thank you all.

[Hobjob]

I think this is Acer macrochelus - a mite gall. Though I have not seen it.

These galls are in/on the veins.

With Acer aceriscampestris the galls are, always (?), pinkish/red and randomly distributed across the leaf. Quite heavily sometimes. They are not pedunculated, but these seem to be. It is quite common. These also look bigger than that.

Acer macrochelus from the FSC British Plant Galls - 2002 edition (a new edition has just be published).
"gall rounded 2-4mm across, with hard walls, often in angle between the veins. Inner surface with many-celled hairs"

Found this footnote - not sure of origin.
A. Macrochelus
In the angle between veins of the leaf protrude globeshaped, to 2 mm high, smooth or scarcely haired, brown to red coloured galls on top of the leaf. Underneath is the gall opening situated. The inner surface and the opening are covered with multi-celled hairs (DvL). There are usually only 8 to 10 galls on a leaf, or more or less.

I have not been able to find a photo on the web, but Acer aceriscampestris can be seen here
http://www.reading.ac.uk/blogs/white...2-1024x661.jpg
or
http://www.naturespot.org.uk/species...eriscampestris

[poschiavanus]

Certainly Aceria macrochelus. This can be expected nearly everywhere on Field Maple (although I struggled to find these 'certs' at a Bioblitz last year), although its a little less obvious than Aceria aceriscampestris.

There are several photos on Flickr (including one or two from WABbers).

[2dogs2000]

Thank you. Your expertise is much appreciated.