Pheidole saxicola, Wheeler, W. M., 1922

Wheeler, W. M., 1922, The ants collected by the American Museum Congo Expedition., Bulletin of the American Museum of Natural History 45, pp. 39-269 : 138-139

Pheidole saxicola , new species

Plate VII; Text Figure 35

Soldier.- Length 5.5 to 6 mm.

Head subrectangular, nearly 3 mm. long and very nearly as broad, scarcely broader behind than in front, with straight subparallel sides, rectangular anterior corners, deeply and angularly excised posterior border, and deep occipital and frontal groove. In profile the occipital region is very feebly depressed and the eyes are small, feebly convex, and at the anterior third of the sides. Gula anteriorly with prominent, blunt teeth. Mandibles convex, with two large apical and two basal teeth and a fewdenticles along the intermediate border. Clypeus convex and carinate in the middle, its anterior border broadly and feebly excised in the middle and sinuate on each side. Frontal carina; very short, diverging; frontal area distinct, with a median carinula. Antenna; slender, scapes reaching the middle of the head; funicular joints all longer than broad; club shorter than the remainder of the funiculus. Thorax shorter than the head, robust, through the pronotum nearly half as broad as the head, with very blunt humeri, convex and rounded in profile. Mesonotum sloping to the deep mesoepinotal constriction with merely a trace of a transverse convexity in the middle. Epinotum broader than long, concave and sloping in the middle, in profile with the base distinctly shorter than the declivity; spines short, suberect, acute, less than half as long as the base and about half as long as their interval. Petiole about one and one-half times as long as broad, broader behind than in front, with concave sides; node transverse, its superior border sharp, feebly excised in the middle. Postpetiole broader than long, about two and one-half times as broad as the petiole, its sides produced as short, acute, slightly backwardly directed spines, its ventral surface with a small, acute tooth. Gaster smaller than the head, subcircular or very broadly elliptical, somewhat, flat tened above. Legs with moderately thickened femora.

Shining throughout; mandibles coarsely striate, smooth and coarsely punctate in the middle. Clypeus longitudinally rugulose, less distinctly in the middle than on the sides. Head rather finely and sharply longitudinally rugose, the rugae diverging on the front and continued to the posterior corners, where they meet the also slightlydivergent rugae between the frontal carinae and the eyes. The interrugal spaces are loosely reticulate. There are no transverse rugae on the occiput but only a finer continuation of the more anterior sculpture. Thorax, petiole, and postpetiole indistinctly and loosely punctate rugulose, the prothorax transversely; epinotum with fine, dense but shallow punctures, so that the surface is more opaque. Gaster with fine, sparse, piligerous punctures.

Hairs yellowish, partly coarse, sparse, uneven and suberect and partly short, much more abundant, softer and appressed or subappressed like long, coarse pubescence. Legs with numerous short, oblique hairs; scapes with a few longer scattered and coarser hairs.

Dark ferruginous red; mandibles, sides and border of clypeus, and frontal carinae, blackish; petiole, postpetiole, and gaster, except more or less of the base of the first segment, dark brown or blackish. Legs a little paler than the thorax.

Worker.- Length 2.7 to 3 mm.

Head subrectangular, as broad in front as behind, with straight, subparallel sides, rounded posterior corners and nearly straight posterior border. Eyes convex, at the middle of the sides. Mandibles rather large, deflected at the tip, with denticulate apical borders and two larger terminal teeth. Clypeus distinctly carinate, with the anterior border very feebly sinuate in the middle. Antennal scapes extending onethird their length beyond the posterior corners of the head. Thorax similar to that of the soldier, but more slender, especially through the pronotum. Base of epinotum a little longer than the declivity; spines slender, acute, eTect, about half as long as their interval. Petiole slender, twice as long as broad, scarcely broader behind than in front, with the sides only very faintly concave; node transverse, its border distinctly notched in the middle. Postpetiole twice as broad as the petiole, as long as broad, subglobose, not toothed on the ventral side. Gaster about as large as the head.

Shining; mandibles subopaque, finely striatopunctate. Sides of head delicately longitudinally rugulose and reticulate. Thorax, petiole, and postpetiole finely and densely punctate, opaque; upper surface of pronotum and postpetiole smooth and shining. Gaster and legs shining, sparsely punctate.

Pilosity like that of the soldier but less abundant. Antennal scapes, like the legs, with numerous oblique hairs.

Brown; head darker above and behind; gaster, except the edges of the segments, middle portions of legs, fore coxae, and usually also the pronotum and upper surfaces of the petiolar nodes, darker than the posterior portion of the thorax.

Described from numerous specimens taken by Lang, Chapin, and Bequaert at Zambi (type locality) and by the latter at Boma.

This ant is certainly very closely related to P. sculpturata Mayr and might be regarded as a subspecies, but it will fit neither Mayr's description of the typical form from South Africa nor Santschi's and Forel's descriptions of the various subspecies from East and West Africa. Mr. Lang's note shows that it is a harvester. '' The nests were found on a dry hilt at the Post of Zambi in rocky soil. One of the entrances, the largest of three, can be distinctly seen in the photograph (Plate VII). The ants excavate their nests in the small amount of soil between the rocks and all or nearly all of them remain under ground during the day. They work during the night up to about 8 A.M. Then the workers may be seen moving along in files, accompanied by the soldiers, and the latter carry seeds for a distance of some fifteen yards. They come and go in different directions indicated by runways left between the accumulated masses of debris and distinctly visible in the photograph. The debris, consisting of seeds and chaff, lies about the nest to a depth of four centimeters and over an area of some sixty centimeters. It is very difficult to obtain a view of the interior of the nest on account of the rocky soil. Some of the kitchen-middens about the nest entrances contained the dried remains of various ants and Coleoptera. In another locality the same species of ant was seen to have collected seeds of entirely different plants but of about the same size."