Definitely take it with a grain of salt. I imagine angle and light refraction in photos could skew it one way or the other erroneously. That's if it's even a reliable characteristic for distinguishing the two. It's one of the reasons I like having certain specimens in hand when possible. Hopefully we'll confirm or correct this one with some more eyeballs taking a look at it. :-)

I moved this one so long ago it's hard to remember my reasoning. :-) I probably went with metallica due to the pronounced metallic blue shimmer given that coracina always seems to be a more charcoal black with far less (if any) metallic blue shimmer. That's what I remember typically being used to "separate" them (and the BOLD specimens *seem to bear this out) but I have no idea if that's actually remotely diagnostic.

It would probably be best to have someone like Ed Knudson take a look at this since my experience with this group is pretty limited (especially west of the Mississippi River), and since both species appear to be sympatric in that area which is essentially Ed's back yard. :-)