Pheidole knowlesi group

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Pheidole knowlesi group, as defined by Fisher et al. 2016.





Major Head subrectangulate to almost square and slightly longer than wide (CI 88–98), with varying sculpture patterns, from mostly smooth or micropunctate ground sculpture between and posterior of longitudinal rugae on frons and sides to mostly punctate ground sculpture with longitudinal rugae on frons and rugoreticulum posteriorly on posterolateral lobes. Mandibles smooth, with two apical teeth and with usually two small basal teeth on masticatory margin, but P. caldwelli with only one slightly larger basal tooth. Frontal carinae posteriorly diverging and relatively long, extending almost 2/3 towards posterior head corners, antennal scrobe present and well to moderately well defined. Hypostoma with small to inconspicuous median tooth, flanked by small to relatively large submedian teeth (see Fig 5). Mesosoma in profile rounded or with posterior process on promesonotal declivity. Propodeum armed with well-developed spines, which are slightly shorter than distance between their bases or longer in P. caldwelli. Postpetiole in profile usually higher than long, in dorsal view on average twice as wide as petiole (PpWI 144–247) and with reduced to moderately long lateral processes.

Minor Head slightly longer than wide (CI 86–96), weakly oval with convex sides and posterior margin moderately narrow and rounded in P. caldwelli and some specimens of Pheidole wilsoni and P. ululevu, but usually broad and straight to weakly concave medially. Posterior promesonotal process absent in most species, but present in P. caldwelli. Propodeum in profile about as high as long, spines usually well-developed and spinose, shorter than distance between their bases in most species, but often longer in P. caldwelli. Petiole with moderately long peduncle, postpetiole shorter than petiole, and about as high as long in profile. Sculpture variable, from partly smooth and shiny or superficially punctate and partly punctate or weakly rugulose to uniformly punctate on almost all surfaces except majority of gaster.


General morphology as in other congeneric species. Head shape square to subrectangulate, usually slightly wider than long (CI 101–111), sides parallel to subparallel, posterior head margin medially weakly concave. Frons with longitudinal rugae, frontal carina relatively long, reaching about 3/4 to 4/5 towards posterior head margin, antennal scrobe about as well defined as in major workers. Mandibles smooth with two apical and usually two small basal teeth along masticatory margin, in P. caldwelli however only one slightly larger basal tooth present. With antennae in repose, apex of scape not reaching posterior head margin and not surpassing posterior end of antennal scrobe. Hypostomal median tooth from relatively large to absent or inconspicuous, submedian teeth varying from large and stout to small and reduced (see Fig 5). Mesosoma with flight sclerites well-developed, in profile dorsal outline flattened with scutum and scutellum forming one horizontal to weakly convex (in P. knowlesi) line, scutum with several longitudinal carinae, in P. caldwelli subparallel and covering entire surface, in other species moderately short to long and forming a V-shape, with remainder of surface smooth and shiny. Postpetiole usually more than two times wider than long (DPpI 206–248) to slightly less than two times wider (DPpI 194) in P. caldwelli.


The knowlesi group consists of five relatively small-bodied, inconspicuous Pheidole species and the slightly larger Pheidole caldwelli. The latter seems to be a relatively rare species within this group, and is only recorded from five localities on Viti Levu, and on Moala Island. The species with the widest distribution in this group is Pheidole ululevu. It was collected on all sampled Fijian islands and, in addition, on Rarotonga (Cook Islands).

Related Pages


  • Fischer, G., Sarnat, E.M., Economo, E.P. 2016. Revision and microtomography of the Pheidole knowlesi group, an endemic ant radiation in Fiji (Hymenoptera, Formicidae, Myrmicinae)Myrmicinae). PLoS ONE 11(7): e0158544. doi:10.1371/journal.pone.0158544.