Nesomyrmex ruani, Mbanyana, N. & Robertson, H. G., 2008

Mbanyana, N. & Robertson, H. G., 2008, Review of the ant genus Nesomyrmex (Hymenoptera: Formicidae: Myrmicinae) in southern Africa., African Natural History 4, pp. 35-55 : 35

Nesomyrmex ruani sp. nov.

Fig. 3a -c

Description of worker

Holotype. HL 0.846, HW 0.696, HW1 0.728, CI 82, SL 0.577, SI 83, PW 0.524, ML 1.119, EL 0.221, EI 32.

Mandibles with fine longitudinal striations. Clypeus with longitudinal striations except for the posterior median portion, which is predominantly smooth. Overall shape of anterior margin convex but median portion slightly concave. Anterior median portion of clypeus straight in longitudinal section. Head in full face view, with hind margin convex. Large eyes with 15 ommatidia in the longest row.

Scapes relatively short (SI <85). Promesonotum in profile evenly convex. Metanotal groove conspicuously impressed. Propodeum unarmed and smoothly convex in profile; anterior dorsum horizontal. Metapleural lobes low and rounded. Subpetiolar process pointed, tooth-like. Petiolar node large and rounded, with anterior facein profile sloping evenly to the dorsum and posterior face nearly vertical. Postpetiole low and rounded. Dorsum of head smooth posteriorly with fine, barely visible, superficial reticulate sculpture; fine longitudinal striations posterior to the vicinity of the frontal lobes and stronger striations between the eye and the antennal sockets. Promesonotal dorsum predominantly smooth, with a few fine short striations on the pronotum. Metanotal groove with cross-ribs. Propodeal dorsum and declivity with transverse striations. Peduncle and petiolar node with transverse rugulae which are continuous around the entire node although they are irregular and faint onthe petiolar dorsum. Postpetiole with fine, transverse, poorly defined, wavy striations. Gastral tergite smooth without costulae at the base. Dorsum of head with approximately eight pairs of suberect hairs, sparse pubescence present. The venter of head with five curved hairs and five long hairs; pubescence present. Promesonotal dorsum with a pair of erect hairs on the pronotal humeri and another pair posteriorly; sparse pubescence present. Propodeum without erect hairs, but with sparse pubescence present. Six suberect hairs on the petiolar node and 10 suberect hairs on the postpetiole; sparse pubescence present. Regularly spaced suberect hairs on the first gastral tergite and sternite, and sparse pubescence presentonthe tergite. Colour uniformly dark brown.

Paratypes. HL 0.824-0.836, HW 0.644-0.674, HW1 0.662-0.694, CI 78-81, SL 0.541-0.553, SI 80-86, PW 0.475-0.511, ML 1.001-1.077, EL 0.210-0.226, EI 33-34 (2 of 3 measured).

Same as holotype except eyes with 15-16 ommatidia in the longest row. Propodeal dorsum either with transverse striations or with longitudinal rugulae. The venter of head with 1-3 curved hairs; 4-5 straight hairs; sparse pubescence present. Petiolar node with three suberect hairs and postpetiole with 6-8 suberect hairs; sparse pubescence present.

Diagnosis

Nesomyrmex ruani is similar in appearance to N. entabeni and N. nanniae : they all have erect hairs on the promesonotum; propodeum forming an even convexity; and colour uniformly light brown.It is distinguished from the latter two species by the sides of petiolar node which are completely covered with strong, sometimes irregular, rugulae. In dorsal view the rugulae are continuous around the entire node. In N. entabeni and N. nanniae the sides of petiolar node have punctulate sculpture or at most with a few weak rugulae. In dorsal view these feeble rugulae may persist, may fade out, or may be replaced entirely with reticulate-punctate sculpture but in no case does the entire node appear to be encircled with strong rugulae everywhere. N. ruani is also larger (HW 0.644-0.690 versus 0.497-0.590).

Biology

Collected from pitfall traps in Mountain Fynbos (Cederberg), and Renosterveld, near Nieuwoudtville.

Etymology

Named after Dr Ruan Veldtman, who assisted Antoinette Botes extensively with her sampling of ants in the Cederberg.

Material examined

Holotype: South Africa: Western Cape: Mountain Fynbos , 32°20'54"S 19°0'17"E, 08 October 2002, A. Botes, CKOct02-NWP-4.4.1 , SAM-HYM-C019398 .

Paratypes: South Africa: Western Cape: Mountain Fynbos, 565 m, 32°20'54"S 19°0'17"E 08 October 2002, A. Botes, CKOct02-NWP-4.4.3 , SAM-HYM-C019404 ; Mountain Fynbos , 332 m, 32°20'20"S 18°59'16"E, 07 October 2002, A. Botes, CKOct02-SAW-3.4.1 , SAM-HYM-C 019403 .

Other material

South Africa: Northern Cape: Glen Lyon farm, Sheep 's Leg Site (4.62 km 153 deg. SSE Nieuwoudtville ), 31°24'22"S 19°9'54"E, 11-18 October 2000, H.G. Robertson, D. Larsen & R. Adams, NW00-TN2-P05 , SAM-HYM-C 019142 .