Ocymyrmex dekerus

Identification
O. dekerus is closely related to Ocymyrmex robustior, Ocymyrmex barbiger, and Ocymyrmex cilliei (barbiger-group). In barbiger and cilliei the eyes are smaller than in robustior and dekerus, and generally fail to break the outline of the sides of the head. Also, the petiole node in the former pair is uniformly strongly sculptured and the cephalic sculpture is strongly developed. O. robustior and dekerus separate on the strength and density of sculpture on the lateral pronotum and on the mesopleuron the oblique costulae are finer and more densely crowded in robustior than in dekerus. Apart from this the clypeal teeth in robustior tend to be longer and more acute than in dekerus, and the occipital margin of robustior is impressed or indented medially, whereas dekerus has this zone transverse or at most extremely feebly concave. (Bolton 1981)

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

Nomenclature

 *  dekerus. Ocymyrmex dekerus Bolton & Marsh, 1989: 1292 (w.) NAMIBIA.

Worker
Holotype. TL 5.8, HL 1.40, HW 1.36, CI 97, SL 1.35, SI 99, PW 0.84, AL 1.80.

Anterior clypeal margin with a median impression. Prominent cuticular flange on anterior clypeal margin narrow and inconspicuous, not a broad lamina. Palp formula 4, 3 (see paratypes). Maximum diameter of eye 0.32, about 0.24 x HW. With the head in full-face view the eyes just intercepting the outline of the sides rather than conspicuously breaking the outline or distinctly failing to reach the outline of the sides. Sides of head in front of eyes parallel, the outline exceptionally weakly concave. Behind the eyes the sides forming an evenly convergent convex broad curve which is confluent with the occipital margin; the latter flattened to very feebly concave medially but not indented. Promesonotum convex, the posterior portion of the mesonotum sloping posteriorly and very shallowly concave to its junction with the propodeum, the latter feebly convex and rounding into the sloping declivity. Metapleural lobe low and rounded in profile, not concealed by the metapleural gland bulla. Node of petiole longer than broad in dorsal view, the postpetiole slightly broader than long and much broader behind than in front. In profile the postpetiolar sternite acutely pointed (see paratypes). Ventrally the postpetiolar sternite with a conspicuous. median longitudinal groove or impression which splits the sclerite into a pair of roughly triangular ventrolateral prominences or tumuli. Gaster in profile with the outline of both the first tergite and first sternite convex behind the articulation with the postpetiole. In dorsal view the base of the gaster not constricted, lacking a neck-like basal area. Dorsum of head very feebly shallowly costulate-rugulose, the sculpture almost effaced in places, .and the ground-sculpture weak to vestigial. Dorsal alitrunk transversely costulate to rugose except for a longitudinal patch centrally on the pronotum and anterior mesonotum. Sides of pro no tum with strongly developed but widely spaced longitudinal costulae, about 12 such costulae present at the pronotal midlength between its basal margin and the level of the base of the mesothoracic spiracle. Remainder of sides of alitrunk obliquely costulate, the components somewhat closer together than on the pronotal sides. Petiole with transverse rugulae ventrally but the sides and dorsum predominantly reticulate to shagreenate. Standing hairs present on all dorsal surfaces of head and body. Colour brown, the head and gaster with a dull yellowish to dull orange tint, the alitrunk with a dull reddish tint.

Paratypes. TL 5.8-6.0, HL 1.40-1.54, HW 1.36-1.48, CI 96-99, SL 1.35-1.42, SI 95-99, PW 0.84-0.90, AL 1.80-1.88 (5 measured).

As holotype but maximum diameter of eye 0.32-0.34 (about 0.22-0.24 x HW). Sides of head in front of eyes vary from very feebly concave to more or less straight in full-face view. One worker has the left maxillary palp 3-segmented, the right 4-segmented; the reduction of the left palp is due to the fusion of the two small apical palpomeres. Shape of the postpetiolar sternite in profile is variable. In the holotype it is acutely pointed on each side, but the para types show variation from this shape to bluntly rounded. Cephalic sculpture is somewhat stronger in some para types than in the holotype, the costulate-rugulose component being more obviously developed. Colour varies from that described above to a more or less uniform light to medium brown, often with a yellowish tint to the gaster.

Type Material
Holotype worker, Namibia ( = South West Africa): 9 mi. NW of Grunau, 1150 m 4.v. 1958 (E. S. Ross and R. E. Leech). Paratypes, 5 workers with same data as holotype (CASC, ).