Ants of the subfamily Pseudomyrmecinae: tabular key to species groups of Pseudomyrmex
About 85% of the 200-odd species in the ant genus Pseudomyrmex can be placed reliably within one of nine major species groups (Ward, 1989). This tabular key summarizes the salient worker characteristics of each of these groups. The table should permit the assignment of most worker-based samples to a species group, but bear in mind that there is a residue of taxonomically isolated species that will not fit the diagnosis of any group. The characters used in this table are explained after the table.
(MSC > 10)
(MSC < 8)
(HTC + MTC > 10)
(HTC + MTC < 8)
|gracilis group||6,4||7-10||rounded1||common3||common3||elongate||pronotum laterally margined|
|tenuis group||6,4||6||rounded||sparse||sparse||elongate||metanotal groove absent|
|sericeus group||6,4; 5,4||8-10||rounded||sparse||sparse||elongate||silky (sericeous) integument|
|pallens group||6,4||5-6||rounded||usually sparse||sparse||variable|
|viduus group||6,4; 5,3; 4,3||5-7||usually rounded2||common||common4||short||broad petiole, PWI > 0.70|
|oculatus group||6,3; 5,3||5-6||rounded||common||usually sparse||elongate||tectiform clypeal lobe|
|subtilissimus group||6,3||5||rounded||sparse||sparse||elongate||frontal carinae elevated|
|pallidus group||5,3; 4,3||5||angulate||sparse||sparse||variable|
|ferrugineus group||5,3; 4,3||6||variable||common||sparse||short||inhabiting swollen-thorn acacia|
1 Somewhat angulate in P. laevigatus
2 Angulate in P. malignus and P. tachigaliae
3 Except P. simulans
4 Except P. tachigaliae
Explanation of characters
The palp formula is the number of maxillary palp segments, followed by number of labial palp segments. In some specimens these segments can be counted in situ; in other instances dissection and slide preparation are necessary.
Number of teeth on the masticatory margin of mandible. This refers to the median number of teeth on the masticatory (biting) margin, within a series of workers from a given nest or population. Mandibular dentition generally shows little variation within a species, but deviations from the “typical” number of teeth occur occasionally. For more details on mandible morphology and terminology see Figure 1 below, which illustrates a mandible bearing six teeth on the masticatory margin.
Median clypeal lobe. The two conditions being contrasted here are an anterolateral margin that is (i) rounded or bluntly angled, versus (ii) sharply angulate.
Mesosomal and tibial pilosity. MSC, MTC and HTC are the number of standing hairs (setae) on the mesosoma dorsum (as seen in profile), external face of mesotibia, and external face of metatibia, respectively. For further details about setal counts see “Use Of Morphometric Measurements”
Eye size. REL is an index of eye size, calculated as EL/HL (eye length/head length). For further details on the measurement of EL and HL see “Use Of Morphometric Measurements”.
- Ward, P.S. 1989. Systematic studies on pseudomyrmecine ants: revision of the Pseudomyrmex oculatus and P. subtilissimus species groups, with taxonomic comments on other species. Quaestiones Entomologicae 25:393-468.