Aceria monspessulani (Cecconi, 1903)
initially white, eventually brown hypophyllous erineum consisting of cylindrical hairs; the leaf locally is somewhat embossed.
Buhr, Farkas, and Dauphin & Aniotsbehere cite the species with Nalepa as author; probably the same species is intended; nevertheless, also check for Aceria acerismonspessulani.
the description above is after Buhr. However, Dauphin & Aniotsbehere give a very different diagnosis: “pouch, widely open at the underside of the leaf”. Buhr’s description is virtually identical with the description of Aculops acericola by Dauphin & Aniotsbehere
Buhr (1964b), Dauphin & Aniotsbehere (1997a), Farkas (1965a), Jočić & Petanović (2012a), Roskam (2019a).