I’m sure that everyone spent the entire weekend contemplating the identity of this mysterious myrmecoid staphylinid (yeah right).
Well, here it goes, the grand unveiling. The mystery staphylinid was Ecitophytes coniceps Wasmann. A rather rare Neotropical army ant guest belonging to the subfamily Staphylininae. This subfamilial placement is apparent is you look at the antennal insertion, mouthparts, prothoracic morphology and tarsal morphology.
Most staphylinines are rather generalized but this species is an exception. As an army ant guest, one can only speculate that this species readily runs amongst their host ant columns.
This staph most likely belongs to the tribe staphylinini. This is pretty evident if you look at the labrum which is highly transverse and deeply emarginate with conspicuous setation. The ultimate antennal segment is also depressed on one surface, creating an asymmetrical profile.
If I were to bet my lunch money I would say it belongs to Philonthina. Why? I don’t know. The ultimate maxillary palp is thinner then the penultimate, plus, anytime there’s a derived* morphologically divergent staphylinine, it always seems to be a philonthine.
* After an email from a blog reader, I am changing “derived” to a non-polar phrase – morphologically divergent. Here I have no evolutionary agenda but have purely taxonomic intentions, not systematic. I must admit I was caught making a mistake that one too many scientists make.