The pale setose ocellar triangle should rule out anything but diversipennis, albipilis, mississippiensis, or illinoensis

Are you just using distribution to go further?

Scutum seems more orangish in albipilis....

I see what you mean now--but if abdominal pilosity is unreliable (as I've already begun to suspect between illinoensis and mississippensis), how are we supposed to tell these apart now? Are you using distribution alone??

Also, I noticed that Curran 1940 recognizes illinoensis and diversipennis as having a lightened femoral apex--the one you identified as diversipennis has an all black hind femur. Is this just another character that proved unreliable?

Thank you so much!

Hi Even,

Yes, it is looking like abdominal pile might not be the best way to tell apart species identity.

We verified that these species were valid and distinct through COI barcodes and used microtrichia patterns on the wing to distinguish between them in the field guide. Obviously these methods aren't applicable to pictures!

Geographic location should be reliable for most cases as the species are not sympatric and their ranges do not overlap. For edge cases we have to be more careful and an expert should look at it.

I also use geographic locality to identify species in the Sphecomyia pattonii complex as it is reliable and the external characters can be difficult to see in photographs.

You can use the wing spots combined with geographic locality as a sort of two-factor authentication. M. diversipennis and M. illinoensis will have brown wing spots. M. albipilis and M. mississippiensis will not have wing spots.

Mallota sackeni is a member of this complex. Additionally, there is a 6th undescribed species in the albipilis complex from Mexico, which has wing spots, but that is outside the scope of Bugguide.

I've emailed you some further questions; if you don't receive it please let me know.