Key to Nesomyrmex species groups of the Malagasy region

This worker key is based on: [[Media:Csosz & Fisher, 2015.pdf |Csösz, S. and Fisher, B.L. 2015. Diagnostic survey of Malagasy Nesomyrmex species-groups and revision of hafahafa group species via morphology based cluster delimitation protocol. ZooKeys. 526:19-59.]] and [[Media:Csosz, S., Fisher, B.L. 2016. Taxonomy of Malagasy Nesomyrmex brevicornis species-group.pdf|Csősz, S. & Fisher, B.L. 2016. Taxonomy of Malagasy Nesomyrmex brevicornis species-group using conventional morphology-based approach. ZooKeys 616: 125–159 (doi:10.3897/zookeys.616.9532).]]

This key was constructed as part of a study of Malagasy Nesomyrmex species. It should work well with species from this region but not for determinations of specimens from other regions.

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 * Nesomyrmex
 * Diagnosis of Nesomyrmex species groups of the Afrotropical and Malagasy regions

1

 * Anterodorsal spines on petiolar node present (Fig. 7) . . . . . hafahafa group


 * Anterodorsal spines on petiolar node absent (Figs 8–11) . . . . . 2

2
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 * Petiolar node globular in dorsal view (Fig. 8), sides strongly convex. Postocular distance vs. petiole width (PoOc/PEW): ≤1.2 [0.72, 1.17]. Sculpture of head, mesosoma, petiole and postpetiole areolate, appears dull. Main sculpture homogenous reticulate, or rugoso-reticulate . . . . . angulatus group


 * Petiolar node long and narrow in dorsal view, sides nearly parallel (Fig 9). Postocular distance vs. petiole width (PoOc/PEW): ≥1.2 [1.2, 2.01]. Ground sculpture on head, dorsum of mesosoma, petiole and postpetiole often, but not exclusively inconspicuous, shiny. Main sculpture variable, coarse to absent . . . . . 3

3
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 * Petiolar node in lateral view higher, (MPST/NOH): 2.41 [1.89, 2.87], propodeal spines moderately long, always present, mesopropodeal depression conspicuous, deep (Fig. 11) . . . . . sikorai group
 * Petiolar node in lateral view lower, (MPST/NOH): 3.54 [2.71, 5.63], propodeal spines very short to absent, mesopropodeal depression variable . . . . . 4

4
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 * Mesopropodeal depression absent (Fig 10, except for Nesomyrmex gibber where a mesothoracic hump is conspicuous). Scape longer SL/CS: 0.72–0.83. Petiole longer (Fig. 9, PEL/CS: 0.44–0.58) . . . . . madecassus group


 * Mesopropodeal depression present and conspicuous (often shallow in Nesomyrmex flavigaster). Scape shorter (SL/CS): 0.49–0.72. Petiole shorter and higher (PEL/CS): 0.34–0.49 . . . . . brevicornis group