Taxonomic history
Raised to species: Wheeler, 1922: 213.Numerous workers from Stanleyville (Lang and Chapin), taken from the leaf-pouches of Cola Laurentii. This form was originally described as a simple variety of the Palearctic P. pygmaea (Latreille) , from specimens taken by Kohl "dans une plante myrmecophile," near Stanleyville. It should, in my opinion, be regarded as a distinct species on account of its peculiar habitat, for pygmsea nests in the soil under stones. Moreover, the worker mediorufa is decidedly smaller, with much shorter antennae, the median funicular joints especially being distinctly shorter than long, whereas in pygmaea they are longer than broad. The head is proportionally smaller and narrower, with more rounded sides and with the occipital border straight or slightly convex, not concave as in pygmaea .
