Review of the ant genus Nesomyrmex (Hymenoptera: Formicidae: Myrmicinae) in southern Africa Nokuthula Mbanyana Natural History Collections Department, Iziko South African Museum, P.O. Box 61, Cape Town, 8000 South Africa E-mail: [email protected] & Hamish G. Robertson Natural History Collections Department, Iziko South African Museum, P.O. Box 61, Cape Town, 8000 South Africa E-mail: [email protected] (with 4 figures) Received 16 July 2008. Accepted 14 October 2008 Members of the genus Nesomyrmex in southern Africa are small, non-dominant, myrmicine ants that nest either in trees (angulatus-group) or in soil (simoni-group). Of the twenty species recorded from this region, the following 15 are newly described: antoinetteae, cederbergensis, entabeni, ezantsi, inye, karooensis, koebergensis, larsenae, mcgregori, nanniae, njengelanga, ruani, saasveldensis, tshiguvhoae and vannoorti. All Nesomyrmex species recorded from southern Africa are described and illustrated, with accompanying information on biology and distribution. Key words: Nesomyrmex, Leptothorax, ants, southern Africa, Nama-Karoo, Succulent Karoo, Fynbos. CONTENTS Abstract · · · · · · · · · · · · · · · · · · 35 List of species from simoni-group· · · · · · · · · · · · · · 43 Introduction · · · · · · · · · · · · · · · 35 southern Africa · · · · · · · · · · · 36 Acknowledgements · · · · · · · · 55 Materials and methods· · · · · · 35 Key to species (workers) · · · · 36 References· · · · · · · · · · · · · · · · 55 Diagnosis of workers in Systematics · · · · · · · · · · · · · · · 38 southern Africa · · · · · · · · · · · 36 angulatus-group · · · · · · · · · · · 38 INTRODUCTION Nesomyrmex is more-or-less confined to warmer areas of Nesomyrmex (Wheeler, 1910) is a genus of myrmicine ants in the Afrotropical and Neotropical Regions (Kempf 1959): 10 the tribe Formicoxenini, members of which until recently species have been recorded from the Afrotropical region were included in Leptothorax. Bolton (2003) divided (Bolton 1982, 2003; Snelling 1992), four from Madagascar Leptothorax (sensu lato) into three genera: Leptothorax (Bolton 2003), and 22 from the Neotropical Region (Kempf (sensu stricto), Nesomyrmex and Temnothorax. Of the three 1959; Diniz 1975; Bolton 2003; Longino 2006). genera, only Nesomyrmex occurs in southern Africa (south The following species of Nesomyrmex have been previ- of the Kunene and Zambezi rivers). Within the Afrotropical ously recorded from southern Africa: angulatus, braunsi, region, there are no records of Leptothorax (sensu stricto), denticulatus, simoni and stramineus. In the revision that while for Temnothorax, two species have been recorded: follows, 15 new species are described bringing the total T. cenatus (Bolton) from Kenya and T. megalops (Hamann number of Nesomyrmex in southern Africa to 20 species. As and Klemm) from Sudan (Bolton 1995; Bolton 2003). The far as can be ascertained, all the new species are ground- nomenclatural history of Nesomyrmex is fairly complex and dwelling and found mainly in the semi-arid regions of southern has been covered by Bolton (2003). Africa (Nama-Karoo, Succulent Karoo biomes) and the Nesomyrmex is separated from Leptothorax and Temno- Fynbos biome. thorax mainly by the median portion of the clypeus, which anteriorly forms a prominent lobe that overlaps and is MATERIALS AND METHODS closely applied to the mandibular dorsum. In profile view the The new species described in this paper are derived from the anterior clypeus overlaps and is closely adherent to the Iziko South African Museum ant collection and are mainly dorsal surface of mandible. In Temnothorax and Lepto- from recent ant surveys conducted in southern Africa, thorax, the median portion of the clypeus does not form an particularly the survey of roadside ants in the Prince Albert anteriorly projecting lobe, and in profile, the anterior region (Tshiguvho et al. 1999), GEF Conservation Farming margin is usually elevated slightly away from the dorsal Project (surveys in Nieuwoudtville and Beaufort West regions) surface of mandible (Bolton 2003). (Robertson & van Noort 2003), Iimbovane Outreach Project 36 African Natural History, Volume 4, 2008 (DST-NRF Centre of Excellence for Invasive Biology (CIB)), can be separated from them mainly by the lateral portions of and the Ph.D. project undertaken from Lamberts Bay to clypeus, which are not raised into a narrow ridge or Cederberg Mountains by Antoinette Botes (also from CIB) shield-wall in front of the antennal insertions, unlike in (Botes et al. 2006). Tetramorium. Nesomyrmex can also be confused with The following measurements were taken using an ocular Cardiocondyla because the median portion of the clypeus micrometer on a Leica MZ 16A stereo microscope: extends over the mandibles in both genera. They are most HL (Head Length): the length of the head proper, excluding easily distinguished by the shape of the postpetiole in dorsal the mandibles, measured in a full-face view, in a straight line view, which in Cardiocondyla is considerably broader than from the anterior-most point of the median clypeal margin the petiolar node. In addition, the eyes of Cardiocondyla are to the mid-point of the occipital margin. in front of the midlength of the sides whereas in Nesomyrmex they are at the midlength. HW (Head Width): the maximum width of the head in We have placed the Nesomyrmex occurring in southern full-face view, excluding the eyes. Africa into two species groups, namely the angulatus-group HW1 (Head Width 1): the maximum width of the head in and simoni-group, which are defined in the first couplet full-face view, including the eyes. of the key below. Besides the morphological differences EL (Eye Length): the maximum diameter of the eye. between them, they also differ biologically because members SL (Scape Length): the maximum straight line measure- of the angulatus-group are arboreal nesters whereas the ment of the antennal scape excluding the condylar bulb. nests that have been found of simoni-group species have all been in the soil. Almost all the specimens examined for the PW (Pronotum Width): the maximum width of the prono- simoni-group were obtained using ground-trapping tum in dorsal view. methods, mainly pitfalls. ML (Mesosoma Length): the length of the mesosoma (= alitrunk) in lateral view from the anteriormost point of LIST OF SPECIES FROM SOUTHERN AFRICA the pronotum to the posterior base of the propodeal lobes. angulatus species-group CI (Cephalic Index): HW divided by HL, ×100. angulatus (Mayr) SI (Scape Index): SL divided by HW, ×100. denticulatus (Mayr) stramineus (Arnold) EI (Eye Index): EL divided by HW, ×100. simoni species-group Geographical coordinates are recorded in the original antoinetteae sp. nov. format they appeared in the label, and where the coordinates braunsi (Forel) are absent, they have been calculated and shown in square cederbergensis sp. nov. brackets after the locality. Specimens were photographed using a GT Ento Vision entabeni sp. nov. Mobile Imaging System. Photographs in Figs 1–4 are ordered ezantsi sp. nov. so that similar looking species are placed together. inye sp. nov. karooensis sp. nov. DIAGNOSIS OF WORKERS IN SOUTHERN AFRICA koebergensis sp. nov. Mandibles with five teeth. Clypeus with a projecting median larsenae sp. nov. portion that overlaps, and is closely applied to, the mandibular mcgregori sp. nov. dorsum; either anterior margin of clypeus evenly convex nanniae sp. nov. along entire length or lateral portions of clypeus more-or- njengelanga sp. nov. less transverse and median portion curving sharply out- ruani sp. nov. wards to form the projecting lobe. Anterior clypeal margin saasveldensis sp. nov. with a pair of hairs straddling the midline; no median seta simoni (Emery) present. Antennal scrobes absent. Frontal carinae absent tshiguvhoae sp. nov. but in some species the frontal lobe is followed by a weak vannoorti sp. nov. longitudinal striation that runs posteriorly and normally ends before the mid-length of the eyes. Antenna with KEY TO SPECIES (WORKERS) 12 segments including a three-segmented apical club. 1. Propodeal spines present: long and narrow, in profile Propodeal spiracle circular, situated high up on the side and distinctly longer than their basal width. Blunt hairs at about the midlength of the segment. Metanotal groove on dorsum of mesosoma. Yellow,tree-nesting species varying from absent to conspicuously impressed. Propo- (angulatus-group). .2 deum armed or unarmed. Petiolar node variable in shape but — Propodeal spines present or absent; if present, short generally nodiform. Anterior peduncle with a tooth-like or and broad: in profile as long as or shorter than their rounded subpetiolar process. basal width. Hairs on dorsum of mesosoma tapering Superficially, Nesomyrmex workers with a rounded or, rarely, blunt. Ground nesting species, variable in propodeum that lacks spines can be confused with colour (simoni-group). .4 Monomorium, but can be distinguished by lacking the 2. Mesosoma forming a single, uninterrupted flat sur- isolated median setae on the anterior clypeal margin. Those face without any trace of metanotal groove. Petiolar species of Nesomyrmex that have the propodeum armed or node without denticles (Fig. 1a,b). angulate, superficially resemble Tetramorium species, and . angulatus Mbanyana & Robertson: Review of the ant genus Nesomyrmex in southern Africa 37 — Mesosoma with promesonotum separated from less than 90 degrees. Head broader (CI 83–84) and propodeum by metanotal groove or impression. Peti- scapes