Ocymyrmex species groups

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The following species groups treatments are based on Bolton, B. and A. C. Marsh. 1989. The Afrotropical thermophilic ant genus Ocymyrmex (Hymenoptera: Formicidae). Journal of Natural History. 23:1267-1308.PDF.

In the earlier taxonomic study of Ocymyrmex it was pointed out (Bolton, 1981) that the members of this genus mostly show a very uniform habitus, making a division of the mass into species-groups rather difficult. Since then the acquisition of new material has to some extent clarified a number of characters and states which could prove of value in the definition of species-groups. Prins and Roux (1989) have made a start by grouping the South African fauna, but the following is a first attempt at outlining potential species-groups for the entire genus.

In the short diagnoses of the groups the term 'gaster not constricted basally' means that in dorsal view the base of the gaster lacks a narrow neck-like section immediately behind the postpetiole. In profile the outline of the gastral base in such forms shows the first gastral tergite and sternite both convex from their articulation with the postpetiole, without a neck-like or narrowly subconical basal outline. Conversely the term 'gaster constricted basally' means that in dorsal view the base of the gaster has a narrow neck-like section immediately behind the postpetiole. In profile in these forms the outline of the first gastral tergite is feebly convex to straight basally, and the first sternite is straight to concave from the articulation with the postpetiole, so that a neck-like or narrowly subconical basal outline is shown.

Palp formula counts are noted as 'predominantly 3, 3' etc., in some cases. This is because of the intraspecific variation of this character.

Ocymyrmex genus page

Key to Ocymyrmex workers

velox group

Gaster not constricted basally. Palp formula 3,3. Clypeal margin lacking a median notch or impression. Median portion of clypeus with anterior section projecting forward, not abruptly truncated.

Distribution: Angola, Namibia.

cavatodorsatus group

Gaster not constricted basally. Palp formula 5, 3. Median portion of clypeus with its anterior section abruptly truncated, vertical or nearly so, lacking a median notch or impression.

Distribution: South Africa.

barbiger group

Gaster not constricted basally. Palp formula predominantly 4, 3. Clypeal margin with a median notch or impression. Anterior cuticular flange of clypeus narrow. Postpetiolar sternite with a median longitudinal groove or impression.

Distribution: South Africa, Namibia.

tachys group

Characters as barbiger-group but palp formula only 2,3.

Distribution: Namibia.

laticeps group

Gaster constricted basally. Palp formula 3, 3. Clypeus lacking a median notch or impression.

Distribution: Angola.

hirsutus group

Gaster constricted basally. Palp formula predominantly 3, 3. Clypeus with a median notch or impression. Alitrunk very densely hairy; sides of pleura and propodeum, seen from above, with very conspicuous long dense projecting white to silvery pilosity.

Distribution: Botswana, Namibia, South Africa, Lesotho.

weitzeckeri group

Gaster constricted basally. Palp formula predominantly 3, 3. Clypeus with a median notch or impression. Alitrunk sparsely hairy; sides of pleura and propodeum, seen from above, with sparse scattered short pilosity to virtually hairless.

Distribution: throughout southern and eastern Africa.