Probolomyrmex brevirostris

The holotype bears a label reading “bei termiten”. Weber's queen was taken “among humus and leaves at the base of a tree with a few bushes forming an island in a banana plantation.”

Distribution based on Regional Taxon Lists
Afrotropical Region: Eritrea, Ethiopia, Uganda, Yemen.

Nomenclature

 *  brevirostris. Escherichia brevirostris Forel, 1910c: 246 (w.) ETHIOPIA. Combination in Probolomyrmex: Taylor, 1965d: 355. Senior synonym of parvus: Taylor, 1965d: 355; Brown, 1975: 11.
 * parvus. Probolomyrmex parvus Weber, 1949b: 3, fig. 2 (q.) UGANDA. Junior synonym of brevirostris: Taylor, 1965d: 355; Brown, 1975: 11.

Worker
Taylor (1965) - Holotype. HL, 0.51 mm.; HW, 0.34 mm.; SL, 0.27 mm.; CI, 67; SI, 79; WL, 0.59 mm.; PW, 0.25 mm.; dorsal petiole width, 0.15 mm.; petiolar node index, 60; petiole height, 0.28 mm.; petiolar node length, 0.20 mm.; lateral petiolar index, 71. General features as in the original description.

This species is apparently unique in Probolomyrmex in the possession of well developed compound eyes in the worker. Those of the holotype are about 0.05 mm. in maximum diameter, with about 14 facets. Their anteriormost points are situated approximately 2•3 times their maximum diameter from the lateral base of the frontoclypeal shelf. It is possible that the holotype is not normal for this character, for it could be a worker-queen intermediate. There is no compelling reason to assume this, however, and the specimen is provisionally accepted as a typical worker. In any case the synonymy of parvus and the distinctiveness of this species in Probolomyrmex would not be jeopardised if the worker was found to be normally eyeless, and such a discovery could only support the synonymy of Escherichia under Probolomyrmex.

The entire body is moderately finely shagreened and there is no trace of an accompanying coarse puncturation. Pilosity and pubescence as in Probolomyrmex filiformis.

Queen
Taylor (1965) - (Based on the holotype of parvus, a dealated specimen.) HL, 0.50 mm.; HW (behind eyes), 0.35 mm.; SL, 0.27 mm.; Cl, 70; Sl, 77; WL, 0.67 mm.; mesonotal width, 0.28 mm.; dorsal petiole width, 0.16 mm.; petiole height, 0.26 mm.; petiolar node length, 0.19 mm.; lateral petiolar index, 73. Differing from the worker in the usual characters. Maximum diameter of compound eyes, 0.11 mm. Form of head, mandibles and petiolar node almost exactly as in worker. Mesosomal structure complete. Sculpturation, pilosity and pubescence developed similarly to those in worker; ground colour slightly darker reddish-brown, eyes dark brown, almost black, each ocellus with an adjacent dark brown spot, suture lines of mesosoma infuscated.

The oral palpi are not visible in the worker, but the general form of the three apical maxillary and the terminal labial palpomeres of the queen is normal for the genus. The terminal maxillary segment is about 5 times as long as broad.