Royidris singularis Bolton & Fisher

Bolton, Barry & Fisher, Brian, 2014, The Madagascan endemic myrmicine ants related to Eutetramorium (Hymenoptera: Formicidae): taxonomy of the genera Eutetramorium Emery, Malagidris nom. n., Myrmisaraka gen. n., Royidris gen. n., and Vitsika gen. n .., Zootaxa 3791 (1), pp. 1-99 : 67-68

Royidris singularis Bolton & Fisher sp. n.

(Figs 78-80, Map 148)

HOLOTYPE WORKER. TL 2.0, HL 0.64, HW 0.53, CI 83, SL 0.64, SI 121, PW 0.37, WL 0.82.

Antennal club 4-segmented. Mandible longitudinally costulate. Scapes relatively long (SI 121); when laid straight back in full-face view the apex of the scape exceeds the posterior margin of the head. With head in full-face view the eyes very close to the midlength of the side of the head capsule. EL 0.15 (EL/HW 0.28). Dorsum of head from level of eyes to posterior margin smooth and polished, unsculptured except for scattered minute punctulae. Promesonotum in profile convex and swollen, the mesonotum posteriorly descends steeply to the metanotal groove, which is narrowly but distinctly impressed. In absolute profile the propodeal dorsum is horizontal, flat to very shallowly convex, posteriorly with a bluntly rounded angle; the declivity is steeply oblique, not vertical. The whole propodeal dorsum is strongly depressed with respect to the highest point of the promesonotum, which is on a considerably higher level. Pronotum with 3 pairs of setae; mesonotum also with 3 pairs; dorsum of propodeum lacks similar standing setae. Pronotal dorsum smooth and shining, polished; propodeal dorsum superficially reticulate-punctulate. Lower side of pronotum weakly reticulate-punctulate, this sculpture fading out on the upper half of the side. Mesopleuron and metapleuron finely reticulate-punctate. Metafemur with MfL 0.60 (MfL/HW 1.13, MfL/ MfH 4.29). Petiole with two pairs of setae, one at the apex of the node, and the other on its posterior face near the apex; postpetiole with setae on its anterior and posterior faces; first gastral tergite with numerous suberect setae that are shorter than the maximum vertical diameter of the eye. Postpetiole relatively narrow in dorsal view, maximum width 0.18 (0.34 x HW). Dorsum of postpetiole and first gastral tergite unsculptured. Colour of head, mesosoma, petiole, postpetiole and legs brown, the head slightly darker than the medium brown mesosoma; gaster black.

QUEEN and MALE: unknown.

Holotype worker, Madagasacar: Iharanandriana, 19°09.49'S, 47°29.82'E, 1513 m., 9.v.2007, BLF 17570, CASENT0128362, uapaca woodland (Fisher et al.) (CASC).

Known only from the holotype and one other worker, this member of the notorthotenes group is characterised by its colour, glassy smooth head and dorsal pronotum, and its relative dimensions as mentioned under the gravipuncta group diagnosis, above. In colour, singularis is reminiscent of pulchra and anxietas , two members of the robertsoni group, but in both these species the antennal club is of 3 segments and the metanotal groove is absent. In addition, pulchra is a larger species, with shorter scapes, distinctly larger eyes and longer metafemora; compare pulchra HW 0.66, SI 112, EL/HW 0.32, MfL/HW 1.32 with the measurements of singularis , above. In the case of anxietas , its scapes are shorter (SI 100-110) than in singularis (SI 121), the head of anxietas has reticulate-punctulate sculpture, and its propodeum usually has a standing short seta close to the posterior angle.

Both specimens were found in uapaca woodland.

Non-paratypic material examined. Madagascar: Mampiarika, Ambositra (A. Ravelomanana).