Ocymyrmex barbiger Emery

Bolton, B., 1981, A revision of six minor genera of Myrmicinae (Hymenoptera: Formicidae) in the Ethiopian zoogeographical region., Bulletin of the British Museum (Natural History) Entomology 43, pp. 245-307 : 265-266

Ocymyrmex barbiger Emery

Ocymyrmex barbiger Emery , 1886: 364, pl. 17 figs 9 - 11. Syntype workers and male, South Africa: Cape of

Good Hope (L. Peringuey) (MHN, Geneva; MCSN, Genoa) [examined]. Ocymyrmex barbatus Emery , 1892: 114,117. [Lapsus for barbiger Emery .] Ocymyrmex barbiger var. robustior Stitz , 1923: 146. Syntype worker, South West Africa: Luederitzbucht,

5 - 13. vii. 1911; and Swakopmund, 12 - 19. iv. 1911 (W. Michaelsen) (MNHU, Berlin) [examined] Syn. n. Ocymyrmex barbiger var. flavescens Stitz , 1923: 147. Syntype worker, South West Africa: Okaputa,

5. v. 1911 (W. Michaelsen) (MNHU, Berlin) [examined]. Syn. n.

Worker. TL 6.7 - 7.2, HL 1.54 - 1.84, HW 1.42 - 1.76, CI 90 - 97, SL 1.38 - 1.58, SI 87 - 98, PW 0.94 - 1.10, AL 2.00 - 2.20 (20 measured).

Anterior clypeal margin with a semicircular median impression which is flanked by a pair of teeth. The impression is usually deep and conspicuous but in some individuals may be broad and quite shallow. The flanking teeth are generally well developed but commonly are broadly triangular and blunted, sometimes little more than broadly rounded prominences. Maximum diameter of eye 0.32 - 0.35, about 019 - 0.22 x HW, in full face view not breaking the outline of the sides of the head. Promesonotum forming an evenly rounded low convexity which slopes downwards behind to the propodeum, the dorsum of which varies from more or less flat to slightly inclined. Propodeal dorsum rounding broadly and evenly into the declivity. Metapleural lobes low but prominent, their free edges rounded to bluntly truncated posteriorly. Petiole node in profile usually quite high, bluntly rounded-subconical in shape, but sometimes the dorsum more flattened and the node appearing less regular in shape. Petiole node in dorsal view usually broader than long, less commonly only about as broad as long. Postpetiole always broader than long in dorsal view, discounting the anterior articulating portion. Base of first gastral tergite without a neck-like constriction. Head finely and densely rugulose, with line punctulate ground-sculpture; the pattern formed by the rugulae very variable on the dorsum but apparently following a step by step change. In many the cephalic rugulae are regular and longitudinal, parallel on the central strip and running straight back to the occipital margin, but the more lateral rugulae tending to diverge and arch outwards behind the eyes. This seems the basic pattern from which the following derive sequentially. Firstly, the median-line rugulae begin to diverge posteriorly, forcing the more lateral rugulae to arch outwards even more. Next, the point at which the median-line rugulae begin to diverge shifts gradually forward, arching the lateral components more strongly outwards all the time. When the point of divergence of the mid-line rugulae has shifted a certain distance forwards a number of V-shaped rugulae appear in front of the impression in the centre of the occipital margin, which occupy the space vacated by the now divergent mid-line rugulae. Then, as the point of divergence of the mid-line rugulae shifts still further forward the V-shaped rugulae also shift forward on the head and their angle becomes more obtuse the further forward they shift. This process continues until ultimately the head is mostly transversely sculptured behind the eyes, although the rugulae tend to retain their broadly V-shaped nature more posteriorly on the head. Pronotal dorsum usually with extensive longitudinal sculpture, the more lateral components arching across in front of the central longitudinals. Space between mesothoracic spiracles usually longitudinally rugose, sometimes obliquely so and very rarely the sculpture here more or less transverse. Remainder of dorsal alitrunk transversely rugose. Petiole with transverse rugulae ventrally which usually extend for some distance up the sides of the node, commonly to the dorsum. In more strongly sculptured samples the rugulae continue across the top of the node but often the dorsum is more weakly sculptured. Postpetiole finely shagreened or with fine superficial patterning only. All dorsal surfaces of head and body with hairs, those on the first gastral tergite more numerous and longer in barbiger than is usual in the genus, the gastral hairs frequently approaching the length and density seen on the alitrunk. Elsewhere in the genus gastral hairs on the first tergite are much shorter and much sparser than on the alitrunk. Colour of head and alitrunk orange to dull brick red, the gaster darker, frequently dull brown with a reddish tint or even blackish brown.

One of three known species in which the base of the first gastral tergite is not constricted to a narrow neck, barbiger is separable from both others showing this character ( cavatodorsatus , turneri ) by its possession of an impressed anterior clypeal margin and its strong sculpture.

Material examined

South West Africa: Maltahoe dist., Sesriem Farm (M. C. Day). South Africa: Cape Prov., Orange Riv., Kakamas (G. Arnold); CP., Orange Riv., no loc. (G. Arnold); CP., Betty's Bay (G. Arnold); CP., Willow-more (G. Arnold); Willowmore (ex coll. Mayr); Willowmore (H. Brauns); CP., Table Mt (G. Arnold); CP., Victoria West (G. Arnold); CP., Mossel Bay (R. E. Turner); CP., Camps Bay (R. E. Turner); CP, Die Panne (M. C. Day); CP., Pt Elizabeth (W. L. Brown); CP, Grahamstown (L. Weatherill & W. L. Brown).