Ocymyrmex ignotus

Identification
A member of the hirsutus-group, ignotus displays the abundant dense pilosity and other characteristics of the group. Species most closely related to ignotus include Ocymyrmex flaviventris and Ocymyrmex resekhes. O. ignotus separates from both of these by having the gaster very dark in colour, blackish and darker than the head and alitrunk as opposed to yellowish or orange and lighter than the head and alitrunk in flaviventris and resekhes. Also, the postpetiole in ignotus is voluminous and has a swollen appearance, with a markedly convex ventral outline. O. ignotus averages larger than flaviventris and has a broader head. It also has a long narrow petiolar peduncle, rather than the short stout peduncle exhibited by flaviventris. The petiole node of ignotus is much broader in dorsal view than that of resekhes and the vermiculate to chaotic areas of cephalic sculpture characteristic of ignotus do not occur in resekhes. (Bolton 1981)

Key to Ocymyrmex workers

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

Nomenclature

 *  ignotus. Ocymyrmex ignotus Bolton & Marsh, 1989: 1297 (w.q.) SOUTH AFRICA.

Worker
Holotype. TL 8.3, HL 1.90, HW 1.90, CI 100, SL 1.76, SI 93, PW 1.22, AL 2.56.

Notch in anterior clypeal margin deep and conspicuous, flanked by a pair of sharp teeth. Palp formula 3, 3. Maximum diameter of eye 0.38, about 0.20 x HW, the eyes distinctly failing to break the outline of the sides of the head in full-face view. Sides of head weakly divergent in front of the eyes, behind the eyes rounding broadly into the occipital margin; the latter feebly indented medially. With alitrunk in profile the meta pleural lobes conspicuous, projecting posteriorly and not concealed by the meta pleural gland bulla. Petiole in profile with an elongate anterior peduncle and a narrowly rounded node. In dorsal view the node stocky and broad, distinctly much broader than long and its maximum width strikingly greater than that of the posterior peduncle (ca 0.44 and 0.32 respectively). Postpetiole in profile swollen, broadly convex both dorsally and ventrally and very much more voluminous than the petiole. Base of gaster strongly constricted. Dorsum of head finely densely and strongly sculptured everywhere. Centrally the head with a longitudinal strip of irregular close-packed rugulae behind the frontal lobes. On each side of this, to the inner margins of the eyes, the surface is blanketed by fine and very dense vermiculate to chaotic rugulae. Dorsal alitrunk transversely rugulose to rugose except for a longitudinally sculptured patch between the meso thoracic spiracles. Sides of alitrunk strongly rugulose to rugose, the sculpture finer on the pronotum than elsewhere. Petiole with transverse rugulae ventrally, but these fading out on the sides of the node, leaving these areas and the dorsum finely shagreenate to superficially reticulate. Postpetiole and first gastral tergite superficially reticulate to shagreenate. Pilosity dense everywhere, the entire body abundantly hairy. Pleurae and sides of propodeum with dense long projecting pilosity. Gaster black, in places with a very faint dull reddish tint. Remainder of body very dull red, the whole ant appearing blackish to the naked eye.

Paratypes. TL 7.9-8.3, HL 1.84-1.90, HW 1.82-1.92, CI 97-102, SL 1.70-1.76, SI 91-95, PW 1.18-1.22, AL 2.46-2.57 (10 measured).

As holotype but maximum diameter of eye 0.20-0.21 x HW. Most para types the same colour as the holotype but some darker, the alitrunk in these blackish and almost the same shade as the gaster.

Type Material
Holotype worker, South Africa: north Cape Province, Pomfret, xii.1986, NCI2A, (A.C. Marsh). Paratypes, 17 workers and 2 ergatoid females, with same data as holotype (BMNH, SAM, ).