Nesomyrmex nanniae, 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 nanniae sp. nov.

Fig. 3g -i

Description of worker

Holotype. HL 0.771, HW 0.590, HW1 0.624, CI 77, SL 0.514, SI 87, PW 0.452, ML 0.910, EL 0.232, EI 39.

Mandibles with fine longitudinal striations. Median clypeus smooth and bordered by longitudinal striations. Anterior margin of projecting median portion of clypeus convex. Eyes large, with 15 ommatidia in the longest row. Head in full face view with hind margin shallowly convex. Scapes of moderate length (SI 87). In profile, dorsal margin of promesonotum evenly convex and confluent with dorsum of propodeum; metanotal groove absent dorsally but evident laterally. Dorsum of propodeum and declivity forming an even convexity in profile; propodeum unarmed. Metapleural lobes low and rounded. In profile, petiole with well-defined peduncle and large rounded node: anterior, dorsal and posterior margins together forming an even convexity. Subpetiolar process barely evident. Postpetiole in lateral view round and almost the same length as the petiolar node. Dorsum of head predominantly smooth and shiny with very faint, irregular striations; short irregular striations between the eyes.

Promesonotum smooth and shining, with very faint irregular striations. Propodeum with fine transverse striations towards the declivity, elsewhere smooth with very faint irregular striations. Metapleuron and side of propodeum partially reticulate punctate. Both nodes dorsally more-or-less smooth with irregular faint reticulation. Sides of both nodes more heavily sculptured with irregular striations. Gaster smooth and shining, with irregular striations. A few long blunt hairs along posterior margin of the head and two longitudinal lines of hairs (at least four per line) posterior to the frontal lobes. The venterof head with one subdecumbent hair and sparse pubescence present. Promesonotum with a pair of erect hairs on the pronotal humeri and another pair further back. Propodeum with no erect hairs. Petiolar node with a single pair of suberect hairs, and postpetiole with three pairs of suberect hairs. Regularly spaced semi-erect hairs on gastral tergite and sternite. Head and gaster with sparse pubescence and occasional sparse pubescence on other surfaces. Colour uniformly dark brown.

Paratypes. HL 0.656-0.747; HW 0.497-0.565; HW1 0.531-0.605, CI 72-76; SL 0.470-0.521; SI 90-96;

PW0.370-0.420;ML0.757-0.870;EL0.187-0.207;EI35-40 (5 of 6 measured).

Same as holotype except the mandibles are either smooth apically, with only longitudinal striations basally or entirely with longitudinal striations. Anterior clypeal margin either convex or more-or-less flattened medially. The venter of head with 1-3 subdecumbent hairs, sparse pubescence present. Hairs on the petiolar node range from 2-4 hairs.

Diagnosis

Nesomyrmex nanniae is similar in appearance to N. entabeni and N. ruani : they all have erect hairs on the promesonotum; propodeum forming an even convexity; and colour uniformly light brown. It is distinguished from N. ruani by the sides of petiolar node which have punctulate ground sculpture or at most 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; in N. ruanisidesofpetiolar node are completely covered with strong, sometimes irregular, rugulae. In dorsal view the entire node with continuous rugulae around it. N. nanniae is also smaller (HW 0.497- 0.590; PW 0.370-0.452) than N. ruani (HW 0.644-0.690, PW 0.475-0.524).

Nesomyrmex nanniae is separated from N. entabeni by the promesonotum and propodeum which are confluent in dorsal view, with no metanotal groove visible medially; in N. entabeni metanotal grooveisclearly defined and has short longitudinal rugulae.

Biology

Four specimens were collected from pitfall traps, one specimenfrom sweepingandtwospecimensfromyellow pan traps, all from Renosterveld on tillite in the Nieuwoudtville region. The fact that during the extensive sampling undertaken for the Conservation Project of the main vegetation types in the region, this species was only captured in Renosterveld on tillite, suggests that it is limited to this vegetation type.

Etymology

Named after Ingrid Nanni, who works for the South African National Biodiversity Institute (SANBI) and who capably managed the Conservation Farming Project that made the collection of these specimens possible.

Material examined

Holotype: South Africa: Northern Cape: Glen Lyon farm, Sheep 's Leg Site (4.62 km 153° SSE Nieuwoudtville ), 31°24.359'S 19°08.895'E, collected in natural Renosterveld on tillite, Pitfall, 11-18 October 2000, H.G. Robertson, D. Larsen, R. Adams, NW00-TN2-P10 , SAM-HYM-C019139 .

Paratypes: South Africa: Northern Cape: Glen Lyon farm, Sheep 's Leg Site (4.62 km 153° SSE Nieuwoudtville ), 31°24.359'S 19°08.895'E, collected in natural Renosterveld on tillite, Pitfall, 11-18 October 2000, H.G. Robertson, D. Larsen, R. Adams, NW00-TN2-P05 , SAM-HYM-C019135 ; Papkuilsfontein farm, Matjie Site (16.7 km 176° S Nieuwoudtville ), 31°30.915'S 19°10.960'E, collected in natural Renosterveld on tillite, Yellow pan trap, 12-19 October2000, S. van Noort & H.G. Robertson, NW00-TN3-Y85 , SAM-HYM-C019137 ; Papkuilsfontein farm, Matjie Site (16.7 km 176° S Nieuwoudtville ), 31°30.915'S 19°10.960'E, collected innatural Renosterveldon tillite, Pitfall, 12-19 October2000, S. van Noort & H.G. Robertson, NW00-TN3- Y86 , SAM-HYM-C019138 ; Trekpad Site (1.70km 336°NNW Nieuwoudtville), 31°21.982'S 19°06.037'E, collected in natural Renosterveld on tillite, Sweep, 15 October 2000, S. van Noort, NW00-TN1-S177 , SAM-HYM-C019136 ; Trekpad Site (1.70 km 336° NNW Nieuwoudtville ) 31°21.982'S 19°06.037'E, collected in natural Renosterveld on tillite, Pitfall, 12-19 October 2000, H.G. Robertson, D. Larsen & R Adams, NW00-TN1-P03 , SAM-HYM-C019133 .