Genus Pheidole Westwood (1839: 219)

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.

Westwood (1839: 219) is attributed with the Genus name but all that was written is: "In Pheidole providens Westw. (Atta p. Sykes. Trans, Ent. Soc. vol i. pl. 13 f.5.)   ... I have only been able to detect two joints in the maxillary palpi". Further (p 221) is "Colonel Sykes, in his history of Pheidole providens W.  The useful Westwood reference is : Westwood, J.A. (1841) The Annals and Magazine of Natural History, 6: 87. See . The Sykes description can be seen on Pheidole providens.

Mayr (1861: 69) gave a genus description, this is at .

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 to compile a key but, for the present, this probably is best used by visual comparison rather than the couplet characters.

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. Wheeler (1922: 806) noted of the Afrotropical forms that all were in the subgenus Pheidole. 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) did not separate species into the subgenera (unlike for Camponotus) and referred to Brown (1973b) as having synonymized all the then subgenera under Pheidole.

Key to Sub-Saharan species

At present (December 2014) this is requires more work but all named species are included

Fischer, Hita Garcia & Peters (2012) recently gave unsubstantiated notes on the genus in the Afrotropical zoogeographical region, with a detailed study of what they termed the Pheidole pulchella group. They made no reference whatever to my work over the previous decade although they gave an extensive, completely unnecessary list of revisionary works on other Afrotropical ant genera.

I have incorporated their species separations and new species. I found their paper poorly edited with a plethora of unnecessary colons in the measurements and indices, so have made minor changes to their text.

Their grouping can be seen on Fischer groups

Forms or morphospecies denoted in various ecological studies

Pheidole species indet. Bernard form

From the Mount Nimba surveys in Guinea, Bernard (1952) noted soldiers from Ziéla, Kéoulenta, 6 winged queens and 10 minors from Mount Tô at 1600 m; all of which he felt unable to classify. They may have been new species but the bibliography and collections of the great Swiss taxonomists were insufficient for him to take any certain decisions.

Strickland (1951a) - Ghana

Strickland mentions there being ten other species found in Ghana cocoa farms, mostly soil species and relatively rare - thus they were not specifically determined. Of greater importance on cocoa were:-

Pheidole species F217.
The commonest of the ten species, first taken from a carton nest in a folded leaf of a forest plant (Diospyros xanthoclamys) at Bunso, and taken most frequently in association with mealybugs on cocoa pods at CRIG.

Pheidole species F522
First taken from a small nest in a split in the bark of a mature cocoa tree.

Pheidole species F530
Taken from an arboreal earthen nest on a forest tree (Pseudospondias microcarpa).

Room (1971) - Ghana

Those from Room's work at the Mampong Cemetery Farm in Ghana (Room, 1971) were listed as -

Pheidole species H
Found also in two cocoa canopy samples. Four minors were found on the ground under Amelonado cocoa at CRIG (Bigger, 1981a).

Pheidole species L
Found also at another six of his cocoa canopy sampling sites. In his studies of the fauna of cocoa mistletoe (Room, 1972a, 1975), it was 19th most abundant insect at the cocoa/mistletoe junction (204 individuals).

Pheidole species A84
From mistletoe in cocoa canopy.

Pheidole species A90
From mistletoe in cocoa canopy and from soil under Euphorbia.

Pheidole species A153
From open ground and on herbs under Euphorbia.

Pheidole species A154
From cocoa leaf litter.

Pheidole species A155
From herb foliage under Euphorbia.

Pheidole species A156
From cocoa leaf litter.

Pheidole species A160
From cocoa leaf litter and herbs under cocoa.

Pheidole species A162
From cocoa leaf litter.

Pheidole species A270
Foraging and nesting in dead wood on ground under cocoa.

Pheidole species A275
From open ground under Lantana.

Room (1975) - Ghana

The same author (Room, 1975) listed four species, from mistletoe in the canopy of Ghana cocoa -

Pheidole species 13
From mistletoe in cocoa canopy.

Pheidole species 60
From mistletoe in cocoa canopy.

Pheidole species 84
From mistletoe in cocoa canopy.

Pheidole species 90
From mistletoe in cocoa canopy.

Majer (1975) - Ghana -

Pheidole species G
From cocoa at Kade, found by Majer (1975).

Bigger (1981a) - Ghana

Pheidole species K
Five minors collected by pkd from cocoa canopy and 26 on the ground under Amelonado cocoa at CRIG (Bigger, 1981a).

Pheidole species M
Eighteen minors were found in one sample on the ground under Amelonado cocoa at CRIG (Bigger, 1981a).

Jackson (1984) - Cameroun

From Cameroun, Jackson (1984) has two further species, determined by Bolton.

Pheidole species 2
The commonest ground ant in all three cocoa plots studied at Nko'emvon, Cameroun. Collected by pitfall trapping and hand searches, with some 400-900 individuals collected in each ground search. Fairly low numbers were found also on the cocoa trees in both plots examined for arboreal species; on 29% of trees in one plot, with 4 trees having more than 50 workers on them. Jackson, however, did not include the species in her consideration of associations between arboreal species. The level of ground insolation made no difference but there was a weak negative association with Pheidole speculifera in the one plot in which the latter occurred. Its main competitor was Myrmicaria opaciventris, with the latter being better able to handle larger solid food sources.

Pheidole species 3
Found in pitfall traps, a total of 115 individuals, in one of the cocoa plots studied at Nko'emvon, Cameroun.

Belshaw & Bolton (1994b) - Ghana

These authors also have the following list of 11 undetermined species from leaf litter in the semi-deciduous forest zone of Ghana, underlining the total taxonomic confusion with this genus.

Pheidole species (indet.) (1)
Described as widespread in Ghana, by Belshaw & Bolton (1994b), who found 778 workers in leaf litter and soil samples at ten locations in the semi-deciduous forest zone.

Pheidole species (indet.) (2)
Described as widespread in Ghana, by Belshaw & Bolton (1994b), who found 5474 workers in leaf litter and 99 in soil samples at twenty locations in the semi-deciduous forest zone.

Pheidole species (indet.) (3)
Found in Ghana, by Belshaw & Bolton (1994b), who collected 180 workers in leaf litter and 74 in soil samples at five locations in the semi-deciduous forest zone.

Pheidole species (indet.) (4)
Found in Ghana, by Belshaw & Bolton (1994b), who collected 67 workers in leaf litter samples under primary forest at Mankrang Forest Reserve and under cocoa at Bunso and CRIG in the semi-deciduous forest zone.

Pheidole species (indet.) (5)
Described as widespread in Ghana, by Belshaw & Bolton (1994b), who found 213 workers in leaf litter and one in a soil sample at nine locations in the semi-deciduous forest zone.

Pheidole species (indet.) (6)
Found in Ghana, by Belshaw & Bolton (1994b), who collected ten workers in leaf litter samples under primary forest at Sui River Forest Reserve and Atewa Forest Reserve, and under cocoa at Asiakwa and Nankasi in the semi-deciduous forest zone.

Pheidole species (indet.) (7)
Found in Ghana, by Belshaw & Bolton (1994b), who collected 98 workers in leaf litter samples at the Atewa Forest Reserve in the semi-deciduous forest zone.

Pheidole species (indet.) (8)
Found in Ghana, by Belshaw & Bolton (1994b), who collected eight workers in leaf litter samples at Atewa Forest reserve and cocoa at Effiduase in the semi-deciduous forest zone.

Pheidole species (indet.) (9)
Described as widespread in Ghana, by Belshaw & Bolton (1994b), who found 496 workers in leaf litter samples at seven locations in the semi-deciduous forest zone.

Pheidole species (indet.) (10)
Found in Ghana, by Belshaw & Bolton (1994b), who collected 74 workers in leaf litter samples under cocoa at Poano and Bunso and secondary forest at Bobiri in the semi-deciduous forest zone.

Pheidole species (indet.) (11)
Found in Ghana, by Belshaw & Bolton (1994b), who collected 30 workers in leaf litter samples at Sui River Forest Reserve in the semi-deciduous forest zone.