So the Phragmidium turned out to be P.violaceum. Different sources reckoned that violaceum was either primarily 3-septate or 4-septate, and bulbosum was mostly 5-septate but up to 7 or so.
As it turned out this example was c.70% 3-septate and 30% 4-septate on a random sample and never more than that. It also has a nice yellow beak which was mentioned somewhere (but which could be common to both species).
Because it's so cool I'm probably going to go overboard with the photos, but I can't help it.Note that the yellow spots are actually raised bumps, although it's diffitult to see in 2-d.