The following account is from Sarnat et al. (2015).
Pheidole anastasii, P. bilimeki and P. punctatissima all belong to the P. punctatissima clade (Economo et al. 2015). These ants are all relatively small species characterized by densely punctate ground sculpture that gives them a dull, matte appearance. Among species treated here, the P. punctatissima clade species are most easily confused with those of the closely related P. flavens complex. Major and minor workers are most reliably diagnosed from those of the P. flavens complex by the relatively broad postpetiole and the matte anterior portion of the gaster in addition to other characters listed in the key. The minor workers can also be confused with those of Asian native P. parva, but can be distinguished by the more uniform and stout mesosomal hairs, and by the antennal scapes which lack erect hairs and tend to surpass the posterior head margin by a distance equal to or greater than eye. In the Neotropics, there are many native species that closely resemble P. anastasii (Wilson 2003), and identification of the minor worker subcaste is especially challenging.
Among introduced members of the clade, the major workers of P. punctatissima are immediately distinguished from those of both P. anastasii and P. bilimeki by the bicolored head. The minor workers of P. punctatissima tend to have narrower posterior head margins and longer antennal scapes than those of P. anastasii and P. bilimeki. Separating P. anastasii from P. bilimeki is particularly difficult. They are most reliably distinguished by ecological characteristics, with the former preferring to nest arboreally and the latter preferring to nest under stones or in dead wood. The morphological characters separating these two species are highly variable, but the major workers of P. anastasii tend more often towards yellow (versus tending towards brown in P. bilimeki) and can have relatively wider heads (HW 0.74–1.16 mm vs. 0.71–1.07 mm). The minor workers of P. anastasii tend to have more narrow heads posteriorly then P. bilimeki and relatively longer scapes (SI 103–125 vs. 95–108). See Longino and Cox (2009) for additional details.
Adding to the already confusing taxonomy separating P. anastasii and P. bilimeki is the widespread application of the name P. floridana Emery to populations across the southern United States. The first record of P. floridana from Florida was the type series described by Emery from Coconut Grove (Miami area) in 1895. Smith (1930) recorded P. floridana in his original list of Florida ants, and added P. anastasii three years later (1933), stating only “This species [P. anastasii], which was originally described from Costa Rica, is recorded here for Florida on the basis of information secured from Dr. Wheeler…I have seen the same species in greenhouses in the District of Columbia, New Jersey, and Illinois.” The previous year (1932) Wheeler, who had received type material of P. floridana from Emery (Wheeler 1908c), included P. floridana and P. anastasii in his own list of Florida ants.
Naves (1985) in his study of Florida Pheidole, also recognized both species and distinguished P. anastasii from P. floridana by the matte base of the gaster in the former and the glossy gaster in the latter. Indeed, the type specimens of P. floridana from Coconut Grove are consistent with this characterization (CASENT0904424, CASENT0904425). Naves wrote that the Miami area was the only place where he was able to locate P. floridana. Pheidole anastasii, in contrast, was reported by Naves as widely distributed across the state.
Deyrup et al. (1988), lamenting the taxonomic confusion surrounding P. floridana, P. flavens and P. anastasii in Florida, stated, “Traditionally (Creighton 1950; Smith 1979) the name P. floridana has been applied to a widespread upland species that has a distinctive matte area on the base of the first gastral tergite and very evenly rugose head…This is the species we report from the Keys [Florida].” Subsequent reviews of Florida ants have thus excluded P. anastasii from their lists (Deyrup 2003; Deyrup et al. 2000; Moreau et al. 2014). Wilson (2003) followed Deyrup in treating all outdoor populations from the United States as P. floridana, but conceded that his concept of P. floridana could represent a northern geographic variant of P. bilimeki or an endemic species modified by intergradation with a P. bilimeki immigrant population.
With respect to all outdoor North American records, we follow Wheeler (1932), Smith (1933), and Naves (1985) in treating the localized glossy-gaster P. floridana as distinct from the widespread matte-gaster species referred to as P. anastasii by the aforementioned authors. However, the relatively short scapes and posteriorly broad heads of the minor workers, together with the habitat and nesting preferences of the matte-gaster species suggests the name P. bilimeki Mayr more accurately applies to this widespread taxon than does P. anastasii Emery. The issue is discussed in further detail under the P. bilimeki section.