Hypoponera obtunsa

Some of the few known specimens of Hypoponera obtunsa were collected from under a stone on a hillside.

Identification
Bolton and Fisher (2011) - Of all the species placed in section 1 of the abeillei group only two are known, Hypoponera lepida and Hypoponera obtunsa, that lack cross-ribs at the base of the cinctus of the second gastral (Abd. IV) tergite; the base of the cinctus is smooth and polished in both. The two species should not be confused, as lepida, apart from its distribution in West and Central Africa, has a larger petiole (PeS 0.220–0.270) that is distinctly higher and shorter, LPeI 38–47, PeH 0.32–0.39.

Also, the sternite of the petiole in lepida has a well-developed ventral process or lobe that has an obliquely descending anterior surface, an angulate to dentiform ventral angle and an ascending posterior surface immediately after the angle that is straight to concave; this structure is absent from obtunsa, where there is no ventral angle and no ascending posterior surface. Finally, lepida is a larger species with longer scapes, HL 0.53–0.58, SL 0.34–0.40, SI 81–91 and is brown to reddish brown in colour.

Key to Afrotropical and West Palaearctic Hypoponera

Distribution
This taxon was described, and is only known, from Zimbabwe.

Castes
Queens and males are known but were not described with the workers.

Nomenclature

 *  obtunsa. Hypoponera obtunsa Bolton & Fisher, 2011: 77 (w.q.) ZIMBABWE.

Non-paratypic material consists of a single square card (BMNH) that carries six poorly mounted workers and an alate male. These are from the same locality as the type-series but are dated 3.xii.1916 on a separate data label. The date is one day different from what is written on the underside of the card, in pencil, “Hillside, Bulawayo, 2.xii.1916, under a stone”.

Worker
(holotype in parentheses). Measurements: HL 0.49–0.50 (0.49), HW 0.40 (0.40), HS 0.445–0.500 (0.445), SL 0.31–0.32 (0.32), PrW 0.28–0.30 (0.28), WL 0.63–0.66 (0.63), HFL 0.34 (0.34), PeNL 0.14–0.15 (0.14), PeH 0.26–0.27 (0.27), PeNW 0.20–0.21 (0.21), PeS 0.200–0.207 (0.207) (5 measured). Indices: CI 80–82 (82), SI 78–80 (80), PeNI 67–75 (75), LPeI 52–58 (52), DPeI 135–150 (150).

Eyes absent. Apex of scape, when laid straight back from its insertion, just fails to reach the midpoint of the posterior margin in full-face view; SL/HL 0.63–0.65. Reticulate-punctate sculpture on cephalic dorsum fine and dense. Punctate sculpture on dorsum of mesosoma feeble and superficial. Mesonotal-mesopleural suture absent. Metanotal groove entirely absent from dorsum; propodeal dorsum much narrower than mesonotum. Propodeal declivity separated from sides by blunt angles, not distinctly marginate. Petiole node in dorsal view relatively narrow, with a convex anterior face and flat to feebly impressed posterior face. Petiole node in profile low and quite long, with a rounded convex dorsal surface; slightly shorter at apex than immediately above level of anterior tubercle. Sternite of petiole in profile without a differentiated lobe; with an obliquely descending anterior face that terminates in a blunt ventral angle; this is followed by a more or less flat ventral surface. Base of cinctus of second gastral tergite smooth and shining in dorsal view, without cross-ribs. Disc of second gastral tergite superficially reticulate-punctate, appearing microreticulate in places; without sharply incised, widely separated punctures. Maximum width of first gastral tergite in dorsal view is subequal to, or slightly less than, the width of the second tergite at its midlength. Midline length of second gastral posttergite, from posterior margin of cinctus to apex, is slightly less than the maximum width of the segment. Full adult colour yellow.

Type Material
Holotype worker (top specimen of three on pin), Zimbabwe (S. Rhodesia on label): Hillside, Bulawayo, 8.xii.1918 (G. Arnold)

Paratypes. 1 worker and 1 dealate queen, mounted below holotype on same pin (BMNH). [Holotype and paratype specimens remounted from a flat card onto points by B. Bolton, iii.2009.]