Well, I have gone through all of my Tapinoma and they are all definitely Tapinoma. No idea what species they are, but they are definitely Tapinoma. I took a look at the key on the Costa Rica Ants page, and also the key on the Ants of Africa page, and tried to use them as guides for important characters. I ended up with four morphospecies (not counting reproductives): 2 species that are small and generally yellowish and whose scapes do not surpass the vertex (or just barely surpass them). One of them has a pair of erect hairs on the pronotum, and one of them does not. The latter may be litorale and the former may be JTL-001 (as described on the Ants of Costa Rica page). And 2 species that are a little larger and generally brownish and whose scapes surpass the vertex by at least 1/4 the length of their scape. One of them has a generally rounder face and scapes that surpass the vertex margin by about 1/4 the length of the scape and one of them has a face that is a little longer than wide and scapes that surpass the vertex by about 1/3 the length of the scape. There's a lot of variation between those last two so they might just be one species, but I am leaving them as two for the moment. They might be ramulorum, ramulorum inrectum or something similar. I'm really not confident enough to give them names at the moment. All of my specimens were collected from canopy foggings. If anybody out there knows anyone interested in Tapinoma, please let me know.
Photo: Tapinoma litorale, Photographer: April Nobile, Location: AntWeb