A taxonomic revision of the cryptic plate-nosed ants of Africa (Formicidae: Proceratiinae: Discothyrea Roger)

Discothyrea, a cryptic genus of proceratiine ants, is revised for the first time in the Afrotropical region. First recorded from the region over one hundred years ago (Emery, 1901), the taxonomy of these specialized ootrophs has not been addressed for the African fauna since the cautious notes of Brown (1958). Comparative morphology and a set of 25 morphometrics were used to qualitatively and quantitatively delineate species. Three species are synonymized and four new species are described, and an illustrated key to the total eight valid species is provided. Antennomere count, previously used exclusively to discriminate species, varies intraspecifically and is diagnostically unreliable. New characters, including eye size, petiole shape, and proportions of the abdominal terga, are informative in species definiton. Two groups, the oculata- and traegaordhi-complexes, are recognized; complex-level characters may be applicable to Discothyrea in other biogeographic regions. The oculata-complex contains two species (D. mixta and D. oculata [=sculptior syn. nov.]) widespread across continental Africa, and one enigmatic new form apparently restricted to montane forests on São Tome. Discothyrea mixta is common in leaf litter samples while D. oculata is rarely collected, perhaps due to nesting lestobiotically in spider oothecae (DeJean 1999).  The traegaordhi-complex includes D. poweri and D. traegaordhi (= hewitti, patrizii syns. nov.), occuring sympatrically in southern and eastern Africa, and three new species inhabiting equatorial forests. This morphology-based alpha taxonomic revision reveals hidden diversity in this poorly-known genus, addresses biogeographic factors in species distribution, and provides a foundation for future study in the Afrotropics and globally.