Key to Afrotropical Centromyrmex species

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The genus Centromyrmex occurs in three regions and includes 15 species and 2 subspecies. These can conveniently be separated into four species groups. The key below include all the Afrotropical species and is based on Bolton & Fisher (2008)[1].


NOTE. The few known queens will also run in this key, except characters relating to shape of mesosoma in workers do not apply to queens.

1

  • Mesotibia with two spurs. Metatibia with two spurs, the anterior spur smaller and simple, the posterior spur larger and pectinate. Propodeal spiracle high on side, close to dorsal outline and at about the midlength of the sclerite. Pronotum not marginate anterodorsally. In profile the propodeal dorsum continues the line of the mesonotal dorsum. Subpetiolar process large, keel-shaped. Metasternal process bispinose. Polymorphic species. (bequaerti group) . . . . . 2
  • Mesotibia without spurs. Metatibia with a single large pectinate spur only. Propodeal spiracle low on side, far from dorsal outline. Pronotum marginate anterodorsally. In profile the propodeal dorsum slopes steeply down from the line of the mesonotal dorsum. Subpetiolar process a short slender spine or small triangular tooth. Metasternal process not bispinose. Monomorphic species. (feae group) . . . . . 3

2

return to couplet 1

  • With mesosoma in profile the bulla of the metapleural gland is short and does not extend to near the base of the propodeal spiracle. Metatibia with spiniform setae such as are seen on the mesotibia. Protibia ventrally with a single stout spiniform seta, similar to those on the mesotibia, located close to the apex on its outer surface, anterior to and opposite the large spur. (Cameroun, Gabon, Central African Republic, Democratic Republic of Congo, Angola, Malawi, Zambia, Zimbabwe) . . . . . Centromyrmex bequaerti
Head of Centromyrmex bequaerti worker
Profile of Centromyrmex bequaerti worker
  • With mesosoma in profile the bulla of the metapleural gland is long and extends to, or even touches, the base of the propodeal spiracle. Metatibia without spiniform setae such as are seen on the mesotibia. Protibia ventrally without a stout spiniform seta that is similar to those on the mesotibia, at most a simple slender seta located close to the apex on its outer surface, anterior to and opposite the large spur. (Gabon) . . . . . Centromyrmex secutor
Head of Centromyrmex secutor worker
Profile of Centromyrmex secutor worker

3

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  • Petiole node in dorsal view conspicuously broader than long . . . . . 4
  • Petiole node in dorsal view at least as long as broad, usually distinctly longer than broad . . . . . 9

4

return to couplet 3

  • Apical third of metatibia with a total of more than 3 thickly spiniform setae that arise from its anterior surface opposite the pectinate spur; one or more thickly spiniform setae also arise from the dorsal (outer) surface of the metatibia in the apical third of its length . . . . . 5
  • Apical third of metatibia with only 1–2 (extremely rarely 3) thickly spiniform setae that arise from the apex of its anterior surface, opposite the pectinate spur; no thickly spiniform setae arise from the dorsal (outer) surface of the metatibia in the apical third of its length. . . . . . 6

5

return to couplet 4

  • Mandible with 5–6 main teeth that are separated by diastemata, the latter are unarmed or have indistinct low crenulations present. With base of gaster in absolute profile the prora is visible as a distinct raised cuticular crest that extends from the base of the helcium onto the anteroventral surface of the first gastral sternite. Smaller species with narrower head and shorter mandibles, HW 1.20–1.34, PW 0.94–1.12, CI 102–105, MI 71–75. (Cameroun, Gabon, Democratic Republic of Congo) . . . . . Centromyrmex decessor
Head of Centromyrmex decessor worker
Profile of Centromyrmex decessor worker
  • Mandible serially dentate, with 10–12 teeth; all teeth are similar in size and without diastemata separating them. With base of gaster in absolute profile the prora is undeveloped, lacking a raised cuticular crest that extends from the base of the helcium onto the anteroventral surface of the first gastral sternite. Larger species with much broader head and longer mandibles, HW 1.92-2.02, PW 1.50-1.62, CI 119-123, MI 82-84. (Zambia, Zimbabwe) . . . . . Centromyrmex raptor
Head of Centromyrmex raptor worker
Profile of Centromyrmex raptor worker

6

return to couplet 4

  • Anterior apex of metatibia with a single thickly spiniform seta, approximately opposite the pectinate spur. (Liberia, Ivory Coast, Ghana, Cameroun, Gabon, Central African Republic, Democratic Republic of Congo, Angola) . . . . . Centromyrmex angolensis
Profile of Centromyrmex angolensis worker
  • Anterior apex of metatibia with two thickly spiniform setae, approximately opposite the pectinate spur . . . . . 7

7

return to couplet 6

  • CI 108–118; at low magnification and in full-face view the head capsule appears conspicuously broader than long. Mandibles relatively slightly longer, MI 68–75. Larger species, HW 0.90–1.13. (Guinea, Ivory Coast, Ghana, Nigeria, Cameroun, Gabon, Democratic Republic of Congo, Uganda, Kenya, Zambia, Mozambique, Zimbabwe) . . . . . Centromyrmex sellaris
Head of Centromyrmex sellaris worker
Profile of Centromyrmex sellaris worker
  • CI 98–101; at low magnification and in full-face view the head capsule appears slightly longer than broad or about as long as broad. Mandibles relatively slightly shorter, MI 59-64. Smaller species, HW 0.65-0.81 . . . . . 8

8

return to couplet 7

  • With mesosoma in profile the slope of the anterior portion of the propodeum is steep and slopes abruptly from the mesonotum. Smaller species, HW 0.65-0.68, WL 1.06-1.14. (Cameroun, Gabon) . . . . . Centromyrmex longiventris
Profile of Centromyrmex longiventris worker
  • With mesosoma in profile the slope of the anterior portion of the propodeum is shallow and slopes only weakly from the mesonotum. Larger species, HW 0.79-0.81, WL 1.31*1.34. (Gabon, Central African Republic, Democratic Republic of Congo) . . . . . Centromyrmex ereptor
Head of Centromyrmex ereptor worker
Profile of Centromyrmex ereptor worker

9

return to couplet 3

  • Basal margin of mandible, from basal tooth to basalmost curve, shallowly convex; basal margin much shorter than masticatory margin. Larger species, HL 1.06, HW 0.99, PW 0.82. (Democratic Republic of Congo) . . . . . Centromyrmex praedator
Head of Centromyrmex praedator worker
Profile of Centromyrmex praedator worker
  • Basal margin of mandible, from basal tooth to basalmost curve, shallowly concave; basal margin almost equal in length to masticatory margin. Smaller species, HL < 0.90, HW < 0.85, PW < 0.70. (Democratic Republic of Congo, South Africa) . . . . . Centromyrmex fugator
Head of Centromyrmex fugator worker
Profile of Centromyrmex fugator worker

References

  1. Bolton, B. and B. L. Fisher. 2008. Afrotropical ants of the ponerine genera Centromyrmex Mayr, Promyopias Santschi gen. rev. and Feroponera gen. n., with a revised key to genera of African Ponerinae (Hymenoptera: Formicidae). Zootaxa 1929: 1-37