|The Ants of
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.
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.
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.
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
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 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.
Pheidole species F522
Pheidole species F530
Room (1971) - Ghana
Those from Room's work at the Mampong Cemetery Farm in Ghana (Room, 1971) were listed as -
Pheidole species H
Pheidole species L
Pheidole species A84
Pheidole species A90
Pheidole species A153
Pheidole species A154
Pheidole species A155
Pheidole species A156
Pheidole species A160
Pheidole species A162
Pheidole species A270
Pheidole species A275
Room (1975) - Ghana
The same author (Room, 1975) listed four species, from mistletoe in the canopy of Ghana cocoa -
Pheidole species 13
Pheidole species 60
Pheidole species 84
Pheidole species 90
Majer (1975) - Ghana -
Pheidole species G
Bigger (1981a) - Ghana
Pheidole species K
Pheidole species M
Jackson (1984) - Cameroun
From Cameroun, Jackson (1984) has two further species, determined by Bolton.
Pheidole species 2
Pheidole species 3
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)
Pheidole species (indet.) (2)
Pheidole species (indet.) (3)
Pheidole species (indet.) (4)
Pheidole species (indet.) (5)
Pheidole species (indet.) (6)
Pheidole species (indet.) (7)
Pheidole species (indet.) (8)
Pheidole species (indet.) (9)
Pheidole species (indet.) (10)
Pheidole species (indet.) (11)
© 2007, 2008, 2010, 2012, 2018 - Brian Taylor CBiol FRSB FRES
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