Moved from Ancistrocerus.

is now needed. But first, this species must be put out of Ancistrocerus. Will someone with editor status do that?

Note the slender first metasomal segment which lacks the carina of Ancistrocerus. The translucent, reflexed, lamellate hind margin of terga 2 and 3 is not visible here (similar to Euodynerus hidalgo which has a very broad segment 1). Not a very common genus. Great to have it finally on bugguide!

This superb Eumeninae strongly reminds of some dark colored, mid-western parper wasps. Although superficially similar to a Symmorphus, it does not belong to this genus because some key criteria don't match. This could well be a genus new for the Guide.
Difficult to say if this female was digging a hole in order to make a nesting burrow, or was only gathering material for her mortar.

Nick is correct. And this is an expert shot of this animal. Large and difficult genus though to call from photos.

I'm not an expert on this group of wasps but this is a solitary species in the subfamily Eumeninae (common name: potter wasps). The long, horseshoe-shaped pronotum would rule out a weevil wasp (if Cerceris and Eucerceris are the weevil wasps you are referring to). Notice the longitudinally folded wings, one of the characters that link them to the rest of the family they belong to-Vespidae (social or "true" wasps). Perhaps someone that knows that family or subfamily better can identify it to a lower taxonomic level.