Aeromyrma petulca, Forel, 1891

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 : 166-168

Aeromyrma petulca , new species

Text Figure 40

Soldier.- Length 2.5 mm.

Head suboblong, nearly one and one-half times as long as broad, with feebly convex sides and rather deeply and angularly excised posterior border. Anterior ocellus well developed; eyes very small, consisting of about six ommatidia, situated at the anterior third of the head. Posterior corners of the latter with a low but distinct ridge produced on each side into a minute tooth. Mandibles convex, with 4 small, subequal, rather acute apical teeth, and a large blunt and flattened basal tooth. Clypeus flat, ecarinate, its anterior border feebly and sinuately excised in the middle, its posterior portion narrow, rectangular, extending back between the diverging frontal carina.. Frontal groove distinct. Antennae 10-jointcd; scapes rather slender and curved at the base, reaching to the middle of the sides of the head; joints 2 to 7 of the funiculus minute, subequal, nearly as broad as long (somewhat too long in the figure); club a little shorter than the remainder of the funiculus, with the basal joint longer than broad and about one-third as long as the terminal joint. Thorax decidedly shorter and narrower than the head; pro- and mesonotum convex, steep in front, rounded above; premesonotal suture distinct; mesonotum subcircular; metanotal sclerite distinct. In profile the dorsal outline of the mesonotum slopes backward continuously with the base of the epinotum without a distinct impression at the mesoepinotal suture. Epinotum with a small tooth on each side, its declivity longer than its base, rather steeply sloping. Petiolar node compressed antcropostcriorly, in profile with a rather angular summit, from above transverse; postpetiole transversely elliptical and somewhat broader than the petiole, with a blunt ventral tooth. Gaster voluminous, distended with a transparent liquid, elongate elliptical, longer than the remainder of the body, its anterior border straight in the middle. Legs short.

Subopaque; mandibles, posterior portion of clypeus, frontal area, mesonotum, and gaster shining; mandibles sparsely and indistinctly punctate; head finely and regularly longitudinally rugulose; sparsely and rather coarsely punctate posteriorly; gaster with fine, scattered, piligerous punctures.

Hairs yellowish, moderately abundant, suberect, of uneven length, most conspicuous on the dorsal surface; very short, dense and appressed on the appendages.

Ferruginous red; legs and antenna: paler and more yellowish; gaster dark brown above, with the venter and bases and apical borders of the segments broadly yellowish.

Described from a single specimen taken by Lang and Chapin at Malela "from a small mushroom-shaped termitarium," probably belonging to a colony of Eutermes fungifaber Sjöstedt.

A. petulca differs from africana Forel from the Kalahari in its slightly smaller size, darker color, in having the postpetiole only slightly broader than the petiole (nearly twice as broad in africana), in possessing epinotal teeth and longitudinal rugae on the head. In africana the head is finely reticulate and the remainder of the body is evidently more shining than in petulca . In nossindambo the head is broader and less sharply rugulose, the thorax is more deeply impressed at the mesoepinotal suture, the antennal scapes are much shorter, the anterior ocellus is smaller and the color is paler.

Forel states that the gaster of the africana, soldier is "transparent yellow," which indicates that it was full of a clear liquid as in petulca . This condition is seen also in the soldiers of many species of Pheidole in Australia and in our Southern States and seems to indicate that this caste in the two genera mentioned often functions as replete or foodstorage individuals as in the honey ants ( Myrmecocystus , Leptomyrmex , Melophorus , Plagiolepis , and Prenolepis ).

Emery1 believes that Aeromyrma , should be reduced to the rank of a subgenus under Oligomyrmex "because in 0. debilis Santschi the worker has 9-jointed, whereas the soldier (and probably also the female) has 10- jointed antennae, so that if one wished to distinguish the groups as heretofore, the worker of 0. debilis would be classified in the genus Oligomyrmex , the soldier in the genus Aeromyrma ." While admitting that the two genera are very closely related, I prefer to retain Aeromyrma as an independent genus until the species are better known. Probably there are important differences in habit between the species of the two groups. At any rate, A. nossindambo and petulca are cleptobiotic with termites, whereas two or three species of Oligomyrmex which I collected in Australia were always found nesting in small cavities in rotten logs quite apart from termites.