Pheidole megacephala (Fabricius)

Major - Minor - Type location not known (Formica megacephala, Fabricius, 1793: 361, major; note Wheeler, 1922, has the type locality as Mauritius = "Isle de France", as per the specimen label, see photomontage below; but Forel, 1891: 176, reckoned the location was Madagascar); duplex (Santschi, 1937d: 218, major, minor & queen) from Angola; ilgi (Pheidole rotundata ssp ilgi, Forel, 1907g: 82, major & minor; Forel, 1907c: 139, queen & male; subspecies of megacephala, Emery, 1915j: 236) from Ethiopia; scabrior (Forel, 1891b: 178, major & minor) from Madagascar, junior synonyms perniciosa (Oecophthora perniciosa, Gerstäcker, 1859: 263, minor; junior synonym of megacephala, Emery, 1915j: 235) from Mozambique; laevigata (Myrmica laevigata, F Smith, 1855b: 130, illustrated, minor; junior synonym of pusilla, Roger, 1859: 259, of pallidula, F Smith, 1858a: 282; of megacephala, Roger, 1863b: 30; of pusilla, Emery, 1915j: 235) from Great Britain [also name used by Mayr, 1862: 747, minor, for specimen from Brazil], suspiciosa (F. Smith, 1859a: 148, minor; junior synonym of megacephala, Donisthorpe, 1932c: 455) from Indonesia, testacea (Atta testacea, F Smith, 1858b: 168, major & minor; junior synonym of megacephala, Brown, 1981: 530) from Brazil .

Fabricius's (1793) description is at . Gerstäcker's (1859) description of perniciosa (worker) is at . Mayr's (1861) description (all forms) is at . F Smith's (1855b) description of laevigata (worker) is at . Forel's (1907g) description of ilgi is at . Emery (1915j) sought to clarify the megacephala-group of species, with and illustrations - see . Emery (1919a) gave notes and illustrations - see . Arnold's (1920a) translation of ilgi (as ilgii) is at . Santschi's (1937d) description of duplex is at .

Notes - changes from the Bolton (1975) listing:

• nkomoana - Forel (1916) felt Ph. megacephala new strips nkomoana could well be a separate species. With my own description and drawings of "Pheidole species E", I have raised Pheidole nkomoana to species status.
• edax - the junior synonym edax (Formica edax, Forskål, 1775: 84, worker) from Egypt is more likely to be a variety of Pheidole pallidula as wide surveys of Egypt have never definitely found P. megacephala.
• pusilla - on examination of the description and illustration of pusilla (Oecophthora pusilla, Heer, 1852: 15, illustrated, all forms; also illustrated by Emery, 1919a) from Madeira (with junior synonyms janus, F Smith, 1858b: 175, illustrated, soldier & worker) from Sri Lanka are clearly not megacephala; pusilla appears to be a distinct species Pheidole pusilla and I have transferred it there.
• janus - from the illustration it has to be said that janus is not a megacephala variety nor would it be P. teneriffana; it seems Wheeler (1922: 812) was responsible for the errors in synonymy. Pheidole janus may well merit revived species status but is extralimital to this website.
• talpa - I agree with Dalla Torre (1893: 95) and Emery (1915j: 235) that Pheidole talpa (Gerstäcker, 1871: 356, soldier; Santschi, 1930b: 67, minor & queen) is a junior synonym of Pheidole punctulata and not of megacephala as thought by Santschi (1925h: 160) and listed in Bolton (1995: 331) - note specially the rhomboid pronotum with acute angles, characteristic of punctulata.
• melancholica - I also regard Pheidole melancholica (Santschi, 1912b), from Ivory Coast, as a distinct species in the crassinoda-group.
• costauriensis - Bolton (1995: 320) had Pheidole rotundata st. costauriensis as "Subspecies of megacephala: current status". Santschi's (1914a, 1915c) descriptions of Pheidole rotundata stirps costauriensis, coupled with Emery's (1915c) drawing of melancholica and my own drawings of "P. crassinoda" have led me to elevate Pheidole costauriensis to species.
• trinodis - from the original description by Losana (1834), it seems obvious that trinodis (Myrmica trinodis, Losana, 1834: 327, illustrated, worker; synonymy Roger, 1863: 30) from Italy, see , is not a junior synonym of megacephala and is not even a Pheidole - Losana emphasises the presence of four spines on the propodeum, i.e. possibly it was a Tetramorium. The confusion by Roger (1863b: 30, followed in Bolton, 1995) probably was caused by Losana's immediately following description of specimens of "the megacephala of Latreille" - as Losana wrote of the ant as nesting in our garden, in Piemonte (Piedmont), in northwest Italy, he almost certainly was reporting on Pheidole pallidula; note his description of a lion-coloured ant.

The photomontage of the holotype (?) is collated from http://www.antweb.org/specimen.do?name=CASENT0101411
Specimen Code Collection Information CASENT0101411; Locality Mauritius: [Ste Catherine]; Collection codes: ANTC3611 Collected by: Linden

Nigerian specimens (Taylor, 1980a: 15). MAJOR ( (apparently somewhat smaller than usual) TL 3.58, HL 1.17, HW 1.24, SL 0.68, PW 0.61
Colour red-brown, gaster darker, appendages lighter. Alitrunk spiculate except for posterior dorsal and lateral areas of the pronotum. Erect hairs relatively long and moderately abundant. Clypeal margin medially concave. Propodeal spines short and acute.

MINOR TL 2.49 mm, HL 0.67, HW 0.58, SL 0.68, PW 0.39
Colour red-brown, gaster darker, appendages lighter. Erect hairs relatively long and moderately abundant. Clypeal margin relatively shallowly convex. Shiny, with only sculpturation on mesonotum, propodeum and petiole, all of which are densely spiculate.

Wheeler (1922) listed megacephala s.s. from Gambia (Dakar, F. Silvestri) and Cameroun (Sjöstedt); costauriensis from Guinea (Kindia and Kakoulima, F. Silvestri) and Nigeria (Ibadan, F. Silvestri).

Excellent illustrations can be seen on the Japanese Ant Color Image Database.

Collingwood (1985), describing specimens he recorded from Saudi Arabia, included the illustration right of the pedicel dorsum and base of the funiculus. He noted promoseonotal outline evenly curved without a distinct mesonotal prominence and funicular segments 2, 3 & 4 not longer than broad.

Bernard (1952) writing on the Guinea findings from Mt. Nimba, urged caution when it came to defining new species. He reported megacephala senus stricto from Gouéla, T 91, grassland at 1600 m (Lamotte), moderately common. Far more abundant was the race melancholica, with a larger and more indented head than the other races (somewhat similar to Pheidole picata but that has a more slender thorax); It was found in the savanna at Yalanzou, Nion, Ziéla and Kéoulenta; and from the forest at diverse altitudes, specially on the crests at 1300-1600 m (where the greatest numbers of soldiers and 2 alated queens were found). He noted the subspecies as known from Guinea, Ivory Coast, Ghana and Nigeria, with varieties from Zaïre and eastern Africa; and described the queen (hitherto undescribed). I have separated Pheidole melancholica as a distinct species, in the crassinoda-group.

Nests in ground or soil in crevices on trees. As well as the abundant findings on cocoa, it was found foraging on native trees, cashew, coffee, kola, oil palm and plantain.

One of the commonest and the most widespread ant species on cocoa in Nigeria, dominant on 12-14% of cocoa trees throughout the cocoa growing area (Taylor, 1977; Taylor & Adedoyin, 1978). Avidly tends Homoptera, of all main types, and constructs tents of soil, plant or arthropod debris or a combination. The tents, especially those constructed of soil, were frequently associated with cocoa black pod infections and because of this, the ant may be one of the main sources of the onset of the black pod epidemic (Taylor & Griffin, 1981). Climb high into the trees, up to 320 cm, making debris tents above about 150 cm.

Strickland (1951a) describes it as abundantly common in Ghana (Gold Coast) cocoa farms. He described it as essentially ground-nesting but added that no attempt was made to distinguish between its numerous varieties and subspecies. An interesting observation was how it was able to repel Crematogaster africana and carry off mealybugs attended by that ant. Curiously, the other more recent reports from Ghana make few references to the species. It was reported from the Mamfe-Mampong cocoa farm in Ghana by Room (1971), but he collected it only on herbs and on the ground; and it plays no part in his report of the ant mosaic. Seventy-seven workers were collected by pkd from the canopy of Amelonado cocoa at CRIG by Bigger (1981a), at a guess these came from a single nest. Strickland (1951a) noted findings on other plants, including plantain (Musa sapientum). Evans (1973) described its role as a vector of Phytophthora pod rot of cocoa in Ghana, but seemed to regard it as most important along the edge of farms and probably most significant early in the season.

Its role as a vector of cocoa black pod disease was confirmed by Babacauh (1982) by experiments at the national School of Agriculture, Abidjan, Ivory Coast. It was soil nesting ants which made tents of soil that acted as vectors and the homopteran involved as an attractant was Planococcoides njalensis.

In the CRIN collection, I separated out what appeared to be a melanistic variety, Pheidole species T³. This was morphologically almost identical but the head of the soldier was slightly more rugose and the minor was very dark with yellow antenna and tarsi. It seemed also to be the more common of the two varieties on unshaded vegetation.

Hall, Cushman et al. (1998) described how ant-tended homopterans indirectly benefit figs (genus Ficus) across southern Africa (Madagascar, Malawi, South Africa, Zambia and Zimbabwe). The most common ant was Pheidole megacephala found on 58% of sampled trees, tending particularly the homopteran Hilda patruelis (Tettigometridae), found on 47% of the fig trees. They noted that they had found the ant also on fig trees in Cameroun.

Majors

The photomontage is of major specimens collected in Gabon, Pongara National Park, Pointe Wingombé; 9-27.vi.2006; malaise trap at edge of forest; collected by Yves Braet.

The photomontage is of major specimens collected in Cameroun, Cameroon 29, Ebodjé, 27.iii.2001, on soil and surface in village; and from Cameroon 109, Yaoundé, on herbaceous vegetation, 20 cm tall, in house garden, 28.iv.2001; all collected by the Doyle Mckey project.

Minors

Minor from Gabon.

Other images of specimens from Gabon can be seen in the folders at - (major) , (major) (minor) (minor) and (majors & minors) Additional images can be seen in the folders at - from Cameroun - . From Mali minors - and Congo minors - .

This may be one of the world's most widely distributed, and perhaps most ubiquitous, tropical species. Hölldobler & Wilson (1990, page 118) picture specimens, from the Pacific Island of Samoa, which look very similar to those I have drawn. They also remark on it being notable for high local abundance and that it often 'extirpates' many other species of ant (pages 399-400). The drawing is from Wilson's (2003) review of the Pheidole of the New World.

There are a number of examples shown on the Antweb pages at http://antweb.org/getComparison.do?rank=species&genus=pheidole&name=megacephala&project=&project=. The queen shown at CASENT0055887, however, seems probably to be an example of Pheidole teneriffana; the major at http://antweb.org/specimen.do?name=casent0101767&shot=p1&project= is the distinct species Pheidole picata from Madgagascar.