? on Acer pseudoplatanus
Acer pseudoplatanus, Zeewolde, Harderbos © Hans Jonkman
detail underside: not just the opening, but also the inside of the gall was hairy
Acer pseudoplatanus, Belgium, prov. Liège, Vivegnis © Jean-Yves Baugnée
galls like these are described, but not named, by Buhr (1964b); according to him several authors associate them with Aceria macrorhyncha.