I'm not very happy with this ID becuase I can not find any info on the cell or leaf sizes of this species.
Leaves are .75 x .25, medial cells average 30X5. Growing on a big leaf maple tree next to a river. There was not much of it there so maybe this is not a very good sample.
Gall on Coyote bush (Baccharis pilularis) induced by a moth (Gnorimoschema baccharisella).
GGNRA - Golden Gate National Recreational Area
Marin County, CA