Viticicola tessmanni, Wheeler

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 : 109-111

Viticicola tessmanni (Stitz)

Text Figures 23 and 24

Worker.- Length 3 to 3.5 mm.

Head longer than broad, a little broader behind than in front, with feebly concave cheeks, rounded posterior corners and nearly straight posterior border, and, on the vertex, with a short longitudinal impression at one end of which the anterior ocellus is sometimes distinctly developed. Posterior ocelli absent. Eyes very small, flat, shorter than half their distance from the mandibular insertions, placed a little in front of the middle of the head. Mandibles short, rather strongly angulate at the base externally, their apical margins oblique, with 5 or 6 denticles, those at the base often indistinct. Clypeus convex and evenly rounded in the middle, its anterior border projecting, entire, strongly emarginate on the sides. Frontal groove absent. Antennae short, scapes not reaching to the middle of the head, first funicular joint much longer than broad, joints 2 to 8 much broader than long, crowded together, joints 9 to 11 forming a three-jointed club, the last joint being as long as both the others, which are subequal and somewhat broader than long. Thorax narrower than the head, constricted in the mesonotal region. Pronotum from above a little broader than long, evenly rounded and convex; mesonotum transversely subelliptical, feebly convex, surrounded by impressed sutures. Metanotum nearly as long as the mesonotum, concave, with uneven surface. Epinotum very convex and rounded, egg-shaped from above, semiglobose in profile, as high as the pronotum or slightly higher, with the slit-shaped epinotal glands shining through the integument and conspicuously enlarged. Petiole short, scarcely longer than broad, broader behind than in front, convex and rounded above. In profile, its ventral surface is also convex and protuberant, with a small, compressed, blunt, translucent tooth anteriorly. Postpetiole a little broader than the petiole, scarcely broader than long and scarcely broader behind than in front, convex and rounded above and below. Legs and gaster of the usual shape, the latter with well-developed sting.

Very smooth and shining, including the mandibles; impunctate under a magnification of 20 diameters.

Hairs golden yellow, erect, of uneven length, sparse, most numerous on the gaster, especially along its sides. These regions also have more numerous short hairs or suberect pubescence. Antennae and legs with shorter, more appressed hairs. Cheeks and clypeus densely and conspicuously pubescent, the latter without a fringe of cilia-like bristles.

Clear brownish yellow, with the borders of the mandibles, clypeus and frontal carinae brown.

Female (dealated).- Length 4.5 to 5 mm.

Very similar to the worker. Thorax elongate elliptical, somewhat flattened above. Mesonotum as long as broad; epinotum subcuboidal, with subequal base and declivity meeting at a rounded right angle in profile, rather sharply marked off by impressed sutures from the more anterior portion of the thorax. Petiole and postpetiole from above subequal and of similar shape, broader than long. Gaster proportionally larger than in the worker.

Sculpture, pilosity and color as in the worker but the hairs and pubescence longer and more abundant. The pubescence is very conspicuous, extending back over the sides and front of the head and especially on the pleura;, epinotum, and nodes of the pedicel. As in the worker, the hairs and pubescence arc longest on the sides of the gaster.

Female (ergatoid.).- Length 3.5 to 4.5 mm.

Intermediate in the structure of the thorax, head, and abdomen between the the worker and true female, possessing ocelli and with the mesonotum varying in size, as shown in the figures (Fig. 23 f-g), as the specimen approaches the worker or female type more closely. The wings are represented by minute brownish or blackish tubercles, the anterior pair with vestigial tegula; at their bases. Some specimens (Fig. 23g) have the fore wings more developed as a pair of triangular pads with indistinct, contorted veins, and folded back over the anterior corners of the epinotum. The pilosity and pubescence are also intermediate between the worker and female; the color the same. Male.- Length 2.6 to 3 mm.

Head, including the eyes, distinctly longer than broad, rounded behind and impressed in front of the anterior ocellus. Cheeks short. Eyes and ocelli rather large, convex. Mandibles small but with distinct, denticulate borders. Clypeus convex, its anterior border rounded and somewhat projecting. Frontal carinae very short. Antennal scapes about three times as long as broad, funicular joints all distinctly longer than broad, cylindrical, very gradually increasing in length to the tip. Thorax narrow and long, flattened above, peculiarly and deeply excavated on the ventral side behind the insertions of the fore coxae; mesosterna swollen. Epinotum resembling that of the female. Petiole and postpetiole much as in the worker, but the former subpedunculate, merging more gradually into the node, without a tooth on its ventral surface. Gaster long and slender. Fore wing with a single cubital cell.

Smooth and shining; hairs and pubescence much as in the worker but less abundant and more delicate.

Color pale yellow of a distinctly lighter tint than in the worker and female. Wings grayish hyaline, with pale brown veins and pterostigma.

Described from numerous specimens of all the phases belonging to a series of several hundred specimens taken at Medje from the hollow stems of Vitex Staudtii Guerke. The relations of the ant to the plant are described in Dr. Bequaert's notes in Part IV, and Prof. Bailey has described the woody structure of the plant and its modification by the ants in Part V.

Stitz described and figured only the worker of this species from specimens taken by Tessmann in Spanish Guinea. He gives the native Pangwe name as "odschigeso" and says that the insect stings more severely than Pachysima aethiops , which is a much larger and more powerful ant. He also describes one of the ergatoid females but seems to regard it as an unusual worker. In my material about 4 to 5 per cent of the specimens are ergatoid females, so that they must form a normal constituent of the colony. They probably function as egg-laying individuals and thus supplement the reproductive activities of the true females, which, judging from my material, are much less numerous.

The adult specimens of V. tessmanni collected by Mr. Lang are accompanied by numerous eggs, larvae, and pupae in all stages. I have figured the adult larva (Fig. 24) because it is interesting in connection with the extraordinay larvae of the two species of Pachysima described below. It resembles the larva of Tetraponera natalensis figured by Emery,1 but is longer and more slender and two of the postcephalic segments bear appendages, the significance of which is more fully explained in my remarks on Pachysima . The prothoracic segment bears a rounded appendage on each side and applied to the side of the head, which, as in the Tetraponera larvae, is overarched by the protuberant, cowl-like prothoracic segment. The first abdominal segment bears ventrally two large and very protuberant appendages which are fused with each other in the middle line. The anterior segments of the body have on their dorsal surfaces clusters of long hooked hairs, as in T. natalensis , and the more posterior segments have simple stiff hairs of very unequal length on their ventral surfaces. There are also numerous short, sparse hairs, scattered over the whole body. The young larvae are essentially like the oldest in form and pilosity. The mandibles are well chitinized and minutely bidentate at the tip as in natalensis , and the head bears minute rudiments of antennae on its dorsal surface. I find also that the larvae of certain East Indian Tetraponerae, e. g., T. allaborans (Walker) , have a similar structure.