Ocymyrmex robustior

Ocymyrmex robustior
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Myrmicinae
Tribe:	Crematogastrini
Genus:	Ocymyrmex
Species:	O. robustior
Binomial name
	Ocymyrmex robustior; Stitz, 1923 Specimen Labels

At a Glance

• Ergatoid queen

Chance observation by Marsh in the Namib Desert indicates that mating almost definitely occurs at night, probably at almost any time of the year, and takes place at the nest entrance of the mother colony. Their main food supply is obtained by scavenging dead or heat-stressed insects. (Bolton and Marsh 1989).

Identification

A member of the barbiger group.

Keys including this Species

Key to Ocymyrmex

Distribution

Latitudinal Distribution Pattern

Latitudinal Range: -22.68333° to -26.62638°.


North Temperate	North Subtropical	Tropical	South Subtropical	South Temperate

Source: AntMaps

Distribution based on Regional Taxon Lists

Afrotropical Region: Namibia (type locality).

Distribution based on AntMaps

Distribution based on AntWeb specimens

Check data from AntWeb

Countries Occupied

Number of countries occupied by this species based on AntWiki Regional Taxon Lists. In general, fewer countries occupied indicates a narrower range, while more countries indicates a more widespread species.

Estimated Abundance

Relative abundance based on number of AntMaps records per species (this species within the purple bar). Fewer records (to the left) indicates a less abundant/encountered species while more records (to the right) indicates more abundant/encountered species.

Biology

In O. robustior, the mean number of workers plus ergatoid queens per nest ± SD was 347.6 ± 170.5 (N = 20). The proportion of ergatoid queens per nest ranged from 0 to 26%, averaging 14.5% (Lecocq de Pletincx et al. 2019). There is only one mated egg-laying ergatoid queen in each colony, and all the others behave like the worker caste. This fits the definition of "multi-purpose ergatoid queens" already studied in Eutetramorium mocquerysi (Myrmicinae) and Mystrium voeltzkowi (Amblyoponinae).

A series of papers focused on Ocymyrmex biology (Marsh, 1985 a, 1985 b), or on Ocymyrmex species as a component of the Namib Desert ant community (Marsh, 1985 c, 1986 a, 1986 b) included information about robustior. In all but the last of these papers the ant referred to as Ocymyrmex barbiger is actually Ocymyrmex robustior. At the times of publication of Marsh's first four papers robustior was incorrectly being treated as a junior synonym of barbiger. The former is now considered to be a valid species, separate from barbiger but belonging to the same species-group. The name robustior was elevated to species-level in Marsh (1986 b).

Castes

Nomenclature

The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

robustior. Ocymyrmex barbiger var. robustior Stitz, 1923: 146 (w.) NAMIBIA. Bolton & Marsh, 1989: 1279 (q.m.). Junior synonym of barbiger: Bolton, 1981b: 265. Revived from synonymy and raised to species: Marsh, 1986: 339. See also: Marsh, 1985: 286; Bolton & Marsh, 1989: 1303.

Description

References

Bolton, B. 1981. A revision of six minor genera of Myrmicinae (Hymenoptera: Formicidae) in the Ethiopian zoogeographical region. Bulletin of the British Museum (Natural History) Entomology. 43:245-307. (page 265, Junior synonym of barbiger)
Bolton, B. and A. C. Marsh. 1989. The Afrotropical thermophilic ant genus Ocymyrmex (Hymenoptera: Formicidae). Journal of Natural History. 23:1267-1308. (page 1279, queen, male described)
Lecocq de Pletincx, N., Kuhn, A. & Aron, S. 2019. Population structure and sociogenetic organisation in a species with ergatoid queens, the desert ant Ocymyrmex robustior. Insect. Soc. https://doi-org.inee.bib.cnrs.fr/10.1007/s00040-019-00697-w
Marsh, A. C. 1985a. Forager abundance and dietary relationships in a Namib Desert ant community. S. Afr. J. Zool. 20: 197-203.
Marsh, A. C. 1985b. Microclimatic factors influencing foraging patterns and success of the thermophilic desert ant, Ocymyrmex barbiger. Insectes Sociaux. 32:286-296.
Marsh, A. C. 1985c. Thermal responses and temperature tolerance in a diurnal desert ant, Ocymyrmex barbiger. Physiological Zoology. 58:629-636.
Marsh, A. C. 1986. Ant species richness along a climatic gradient in the Namib Desert. Journal of Arid Environments. 11:235-241.
Marsh, A. C. 1986b. Checklist, biological notes and distribution of ants in the central Namib Desert. Madoqua 14: 333-344 (page 339, Revived from synonymy, and raised to species)
Reznikova, Z. 2020. Spatial cognition in the context of foraging styles and information transfer in ants. Animal Cognition. (doi:10.1007/s10071-020-01423-x).
Ruano, F., Tinaut, A., Soler, J.J. 2000. High surface temperatures select for individual foraging in ants. Behavioral Ecology 11, 396-404.
Stitz, H. 1923. Hymenoptera, VII. Formicidae. Beitr. Kennt. Land- Süsswasserfauna Dtsch.-Südwestafr. 2: 143-167 (page 146, worker described)
Wehner, R. 2009. The architecture of the desert ant's navigational toolkit (Hymenoptera: Formicidae). Myrmecological News 12, 85-96.

References based on Global Ant Biodiversity Informatics

Bolton B., and A. C. Marsh. 1989. The Afrotropical thermophilic ant genus Ocymyrmex (Hymenoptera: Formicidae). Journal of Natural History 23: 1267-1308.
Campbell H., M. D. E. Fellowes, and J. M. Cook. . Species diversity and dominance-richness relationships for ground and arboreal ant (Hymenoptera: Formicidae) assemblages in Namibian desert, saltpan, and savannah. Myrmecological News 21: 37-47.
IZIKO South Africa Museum Collection
Lecocq de Pletincx, A. Kuhn, and S. Aron. 2019. Population structure and sociogenetic organisation in a species with ergatoid queens, the desert ant Ocymyrmex robustior. https://doi.org/10.1007/s00040-019-00697-w
Marsh A. C. 1986. Checklist, biological notes and distribution of ants in the central Namib Desert. Madoqua 14: 333-344.
Stitz H. 1923. Hymenoptera, VII. Formicidae. Beiträge zur Kenntnis der Land- und Süsswasserfauna Deutsch-Südwestafrikas 2: 143-167.