Oops; the Roman term for it was digitus impudicus; I was getting it confused with fungus.

Also; had a chance to raise the subject of insulting gestures with someone from rural Turkey (Trebizond!); she'd never heard of it, so I'm guessing that it may no longer be a current gesture.

(That said, the Ayyubids of C.11th/12th Egypt and Syria have comparatively little in common with modern Turks, so it isn't necessarily a bogus source.)