SUBFAMILY MYRMICINAE - Genus Pheidole
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The Ants of Africa SUBFAMILY MYRMICINAE - Genus Pheidole |
| Contents - Myrmicinae - MYRMICINAE Introduction |
In Tribe PHEIDOLINI. In great need of revision.
Diagnostic Features - Dimorphic, intermediates rare. Antennae 12-segmented, with a 3-segmented club. I opt for the term major worker, rather than soldier, as there is little, if any, evidence for this form being important in defence, it seeming rather that the evolution may be of a form with powerful seed-crushing mandibles and an enlarged head to accomodate the muscles. That, however, is speculation.
Major worker, often called a soldier, with a massive head and the occipital margin deeply impressed centrally. Mandibles large, heavy and strongly curved; each usually with three teeth, two apical and one basal with an intervening diastema. Eyes forward of the mid-length of the head. Promesonotal suture rarely present. Metanotal groove deeply impressed. Propodeum with a pair of spines or teeth. Petiole usually emarginate dorsally
Minor worker with the occipital margin shallowly emarginate or more usually with the sides of the head converging behind the eyes, to give a very short occipital margin. Mandibles usually with two or three large apical teeth subtended by a row of denticulae. Remainder as in the major, but the eyes are usually at or just forward of the midlength of the head.
Mayr (1861: 69) gave a genus description, this is at
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A very large and taxonomically confused genus, with a multiplicity of nesting sites and foraging habits. Bernard (1952) noted there were 76 species known from Africa, of which 44 were from "French West Africa"; and described the classification as a maze, complicated by the presence of minors and true majors, with enormous heads. Because of the relative similarity of males, queens and minors, he found the majors with distinct variations to be the only useful form for distinguishing species. Personally, I too found the majors, in general, to be much more useful in distinguishing the various species.
In terms of habits, Bernard (1952) regarded Asian species as strictly granivorous but the moist tropical conditions of Africa mitigated against this and most African species are omnivorous. The majors he described as dual functional - cutting up large food particles and defending the colony.
I have attempted (2003/4) to compile a key to those species for which I have sufficiently detailed descriptions and/or have illustrations.
Like Wilson (2003), who now has recognised 624 species from the Americas, only two of which, megacephala and teneriffana, are of Old World origin, I have not used the old subgenus separations. However, following the key to subgenera in Wheeler (1922), what I call the teneriffana group might match the Subgenus Scrobopheidole Emery - "head of major dull, densely sculptured all over; last joint of funiculus not longer than the preceding two joints together". Otherwise, there is the blanket, catch-all, Subgenus Pheidole sensu strictu - which clearly has no use for all the recorded variations.
Bolton (1995) does not separate species into the subgenera (unlike for Camponotus) and refers to Brown (1973b) as having synonymized all the then subgenera under Pheidole.
Provisional key to majors of species and separable forms - Provisional key to minors of species and separable forms
Forms or morphospecies denoted in various ecological studies
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MYRMICINAE Introduction | © 2007, 2008 - Brian Taylor CBiol
FIBiol FRES 11, Grazingfield, Wilford, Nottingham, NG11 7FN, U.K. |
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