I'm a complete amateur.
Is there something that I can look at, gross morphology, that can help me compare? (I did notice that the blue at the edge was not as brilliant as I'd seen before, not that that means anything.)

is by Purrington & Drake (2005)(1). You dorsal habitus image does not appear robust/broad enough to be "depressus" and the quoted body length falls short of most "depressus", that is, ABL ≥ 28 mm vs ≤ 26 mm for most "elongatus". The most reliable external separator is shape of the prosternal process (conical vs roundish) as described in the key. In "depressus", the male metatibia (distal third) bears no golden tuft of hairs, but present so in male "elongatus".

p.s. I incorporated the above distinctions into the Pasimachus genus Info page.