Ocymyrmex alacer

Bolton (Bolton and Marsh 1989) has observed from dissections that the ergatoid like queens of this species have larger, and many more, ovaries than workers.

Identification
A member of the hirsutus group. O. alacer is closely related to Ocymyrmex sphinx, but workers and ergatoid females of these two large species can be separated by characters of the petiole and the pilosity. The form of the petiole in alacer workers is quite different from that of sphinx. In sphinx the node in profile is low and rounded dorsally, and is encircled by rugular sculpture. In dorsal view the sides of the node are rounded and evenly convex, not projecting as triangular prominences as they do in alacer. The posterior face of the node is not flattened in sphinx. Pilosity is conspicuously shorter and much less abundant in sphinx. On the propodeal dorsum the longest hairs are distinctly shorter than the length of the spiracle, and those on the pleurae are very short and less conspicuous. (Bolton and Marsh 1989)

Distribution based on Regional Taxon Lists
Afrotropical Region: Botswana, South Africa.

Nomenclature

 *  alacer. Ocymyrmex alacer Bolton & Marsh, 1989: 1290, fig. 9 (w.q.) SOUTH AFRICA.

Worker
Holotype. TL 9.8, HL 2.24, HW 2.12, CI 95, SL 2.10, SI 99, PW 1.38, AL 3.04.

Large species. Anterior clypeal margin with a conspicuous median impression which is flanked by a pair of short triangular teeth. On each side of the teeth, and confluent with them, a narrow smooth lamella extends along the anterior clypeal margin almost to the level of the anterior tentorial pit. With the head in full-face view the eyes conspicuously fail to break the outline of the sides of the head. Maximum diameter of eye 0.44, about 0.21 x HW. Sides of head weakly divergent from level of eyes to clypeus. Behind the level of the eyes the sides convex and converging posteriorly, rounding very broadly and evenly into the occipital margin; the latter shallowly convex and weakly indented medially. Promesonotum rounded and convex in profile. Propodeal dorsum weakly sloping posteriorly, rounding very broadly into the declivity, which is shallowly convex above the level of the metapleural lobes. In profile the bulla of the metapleural gland not concealing the metapleural lobes, the latter short and not strongly prominent. Peduncle of petiole weakly sinuate ventrally, lacking a conspicuous ventral process. Node short and low, its dorsal outline broadly triangular in profile. In dorsal view the node much broader than long, flattened behind its highest point and its central portion strongly expanded laterally on each side so that the median section of the node projects as a blunted triangular prominence on each side. Maximum width of petiole node about 0.60, approximately three times wider than the length of the posterior petiolar peduncle, and more than four times wider than the anterior peduncle at its narrowest point. Postpetiole in dorsal view fractionally longer than broad, broadening from front to back. Sternite of postpetiole with a marked median longitudinal impression running its length. Base of first gastral tergite narrowed in dorsal view, no broader than the postpetiole. In profile the first gastral tergite outline more or less flat basally, the first sternite very shallowly concave. Dorsum of head finely, densely and irregularly longitudinally rugulose, the rugulae most regular near the cephalic midline. The rugulae arch outwards behind the eyes and are less strongly developed on the occiput than elsewhere. Dorsal alitrunk transversely rugose, the rugae arched on the pronotum; patch between mesothoracic spiracles longitudinally rugose. Sides of alitrunk and propodeal declivity rugose, the sculpture arched-longitudinal on the lateral pronotum, oblique and less regular on the mesopleuron, longitudinal and irregular on the propodeum, transverse on the declivity. Petiole in dorsal view with transverse weak rugulae from mid length of peduncle to node, rugulae stronger on anterior face of node, stronger still and more obviously transverse on posterior face of node. Sides and ventral surface of peduncle predominantly finely reticulate, with some faint transverse rugulae under the node. Postpetiole superficially reticulate everywhere. Pilosity white to silvery, abundant and very dense on all dorsal and lateral surfaces of head and alitrunk; also many conspicuous long hairs present on petiole node and postpetiole. Hairs on gaster much shorter and sparser than on propodeum, the gastral hairs less than half the length of the longest propodeal hairs, the latter at least as long as the propodeal spiracle. Head dull red; alitrunk darker red, almost maroon; gaster lighter, with an orange or yellowish tint.

Paratypes. TL 9.4-9.8, HL 2.20-2.30, HW 2.08-2.20, CI 93-97, SL 2.02-2.12, SI 95-100, PW 1.34-1.40, AL 2.85-3.10 (8 measured).

As holotype but in some the rugular sculpture of the petiole more pronounced. The sides of the head in a few are more strongly divergent anteriorly than in the holotype. Range of eye size is 0.44-0.46, about 0.20-0.21 x HW.

Queen
Paratypes. Answering to description of worker; extremely ergatoid as in all females of this genus. Differing from worker in standard features of antennal scape, frontal lobes and cephalic sculpture as mentioned under the diagnosis of this caste, above, and as described in Bolton (1981). Ergatoid females of this species also tend to have the eyes relatively fractionally smaller, and the petiole node broader, than in the workers.

Type Material
Holotype worker. South Africa: north Cape Prov., Tosca, no. 13. i.1986, (A.C. Marsh). Paratypes. 4 workers with same data as holotype but no. 1; 5 workers and 4 ergatoid females with same data as holotype but no. 2 (BMNH,, ).

References based on Global Ant Biodiversity Informatics

 * Bolton B., and A. C. Marsh. 1989. The Afrotropical thermophilic ant genus Ocymyrmex (Hymenoptera: Formicidae). Journal of Natural History 23: 1267-1308.
 * IZIKO South Africa Museum Collection