...for posting the last two additional head views!

Your photo above is just about perfectly "straight-on"...and thus serves better to assess the divergence vs. convergence of the lower inner margins of the eyes, e.g. in comparison with Figs. 31 and 35 of James(1)(1960), and the MCZ type images below:

      tumida         arcuata

I have to say, the inner orbits here don't look as "divergent" as I had anticipated from the more oblique view in the 3rd of your three photos initially posted. In fact, they look like they trend towards nearly parallel below!

So the trend of the inner orbits, as well as the form of the black marking above the antennae, seem to conform more with O. arcuata; while the relatively wide and forwardly swelling face tend more towards O. tumida...as do the tergal markings. (If we reject the choice of tumida in the key of James(1974), we end up at O. arcuata alticola...but that taxon is characterized as having "transverse dark bands of abdominal terga of female attenuated laterally in the form of a semi-ellipse" (which I presume was the source of the nominal epithet "arcuata").

Separating the two species here is more murky than I'd like, but overall I'd say O. tumida still seems the better call. However, if a large sample of individuals were found to fall in an "intermediate" category like this, it would seem to me to call into question the presumption that tumida and arcuata are distinct biological species (rather than two forms within a single variable species).

This is interesting...let's see what others with more experience make of the situation here (i.e. Norm Woodley, Martin, =v=, etc.).

Moved from Odontomyia arcuata-group.

See comments above, and below 1st image of this series.