The P. flavens-complex is defined here to include P. flavens Roger, P. moerens Wheeler and their respective junior synonyms. A more detailed taxonomic study of this species complex across its geographic range and morphological analysis of available type material is required before P. flavens Roger and P. moerens Wheeler can be reliably diagnosed from each other. Wilson (2003: 374) loosely defined the P. flavens complex as a group of species within the P. flavens clade. The P. flavens clade as defined by Wilson  is now known to be polyphyletic , and unpublished data analyzed by the authors suggests that the P. flavens complex as defined by Wilson also lacks monophyly. Our use of the term P. flavens complex in the context of this paper is limited to P. flavens Roger, P. moerens Wheeler and all taxa treated by Wilson as their junior synonyms. Pheidole exigua is morphologically quite similar the aforementioned taxa, and future attempt to define the flavens complex clade should include it in analyses, along with P. glomericeps and possibly other species not initially considered by Wilson. A clear understanding of the phylogenetic relationship among the aforementioned taxa and the species currently being treated as P. flavens and P. moerens that are invading regions outside of the Neotropics remains a challenge for future studies.
- , Pheidole of the New World: A dominant, hyperdiverse ant genus. Cambridge, MA: Harvard University Press, 2003, p. [ix] + 794.
- , “Unraveling the evolutionary history of the hyperdiverse ant genus Pheidole (Hymenoptera: Formicidae)”, Molecular Phylogenetics and Evolution, vol. 48, no. 1, pp. 224 - 239, 2008.
- , “First record of a species from the New World Pheidole flavens-complex (Hymenoptera: Formicidae) introduced to the southwestern Pacific”, BioInvasions Records, vol. 3, no. 4, pp. 301 - 307, 2014.
Naves  discussed some of the biology of the species treated as P. moerens from the southeastern United States, “The species was found nesting in various places such as under boards, at base of oak trees and fence posts, along roots, under palm leaves, inside wall crevices, and rarely in the ground. Usually small chambers are constructed. It is a monogynous species which has a small blackish female. Its main flight is usually in July. Several queens may start founding a nest, but before the first brood emerges, the dominant female will have killed the others. The chambers usually are built with small soil or debris particles and have small openings. A colony may have over 100 majors and over 500 workers. They feed on seeds and scavenge and prey on small dead or live arthropods. They forage very close to the nesting sites and sometimes a major is found foraging along with the workers.”
- , “A monograph of the genus Pheidole in Florida, USA (Hymenoptera: Formicidae)”, Insecta Mundi, vol. 1, pp. 53-90, 1985.
Diagnosis among introduced Pheidole. Color variable. Major | Head rectangular. Longitudinal carinae extend from anterior frons margin variable distance beyond frontal carinae, but never reach posterior head margin. Rugae of posterolateral lobes variable from mostly absent, to predominantly longitudinal, to distinctly reticulated. Posterior head margin always free of distinct rugae or rugoreticulum. Microsculpture of posterolateral lobes variable from smooth and shining to moderately punctate. Hypostoma with stout median and submedian teeth. Promesonotal dorsum usually with distinct transverse striae, but sometimes lacking distinct striae. Promesonotum in profile forming a single dome, lacking a distinct mound or prominence on the posterior slope. Promesonotum not strongly transverse with strongly projecting sides in dorsal view. Postpetiole not swollen relative to petiole. Postpetiole relatively narrow in dorsal view; distinctly less than 2x petiolar width. Gaster with entire first tergite smooth and shining. Minor | Head covered in punctate microsculpture, giving it a dull appearance. Posterior portion of head lacking many short to medium length segments of striae distinctly interlaced among punctate ground sculpture. Antennal scapes often, but not always, surpass posterior head margin; if they do it is usually by a distance less than eye length. Antennal scapes with standing hairs present. Promesonotum in profile forming a single dome, lacking a distinct mound or prominence on the posterior slope. Hairs on mesosoma fine and flexuous, not arranged in pairs. Pronotal humeri not angular. Postpetiole not swollen relative to petiole. Postpetiole relatively narrow; distinctly less than 2x petiolar width in dorsal view. Gaster with entire first tergite smooth and shining.
Distribution. The native range of the P. flavens complex, as defined here, is the Neotropics. The Caribbean, in particular, appears to be a bastion of diversity. The introduced occurrences presented here include records of species reported as P. flavens, P. moerens and P. flavens-complex. NEOTROPICAL : Cocos Is. (Costa Rica) [as P. moerens], Galapagos Is. [as P. flavens]. AUSTRALASIA Hawaii Is [as P. moerens], Vanuatu [as P. flavens-complex]. NEARCTIC. USA: Alabama [as P. moerens], California [as P. moerens], Florida [as P. moerens and P. flavens], Louisiana [as P. moerens], Mississippi [as P. moerens], Texas [as P. moerens], Washington (in hothouse) [as P. moerens].