Tetramorium rufescens

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Tetramorium rufescens
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Crematogastrini
Genus: Tetramorium
Species group: solidum
Species: T. rufescens
Binomial name
Tetramorium rufescens
Stitz, 1923

Tetramorium rufescens casent0217976 p 1 high.jpg

Tetramorium rufescens casent0217976 d 1 high.jpg

Specimen Labels

A common ground-nesting species that has been collected across a range of open habitats, e.g., rocky slopes, shrubland, desert, and floodplain.

Identification

A member of the T. solidum species group.

Mbanyana et al. (2018) - The description of this species matches that of Bolton (1980) except for colour variation, from red to light brown, observed in specimens examined from South Africa (Klein Pella) and Namibia (Kamanjab, Luderitz District, Daberas, Hobatere, Epupa Falls). The following character combination distinguishes T. rufescens from Tetramorium glabratum and Tetramorium signatum: dorsum of mesosoma with dense reticulate punctate sculpture and propodeal spines long and narrow (PSLI 16–23).

Keys including this Species

Distribution

Tetramorium rufescens has been recorded from South Africa (Western Cape, Northern Cape, Gauteng, Eastern Cape and KwaZulu Natal); and Namibia.

Latitudinal Distribution Pattern

Latitudinal Range: -20.18333° to -33.3°.

   
North
Temperate
North
Subtropical
Tropical South
Subtropical
South
Temperate

Distribution based on Regional Taxon Lists

Afrotropical Region: Mozambique, Namibia (type locality), South Africa.

Distribution based on AntMaps

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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.

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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.

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Habitat

Known from Drakensberg Montane Grassland, Kalahari Xeric Savanna, Nama Karoo, Namib Desert, Namibian Savanna Woodland, Succulent Karoo, and alluvial habitats.

Hawkes, 2020. Figure 3b, c. Northern Richtersveld National Park, Namakwa district, Northern Cape, South Africa. Tetramorium pogonion and Tetramorium rufescens were collected from these B) alluvial terrace gravel and C) alluvial fan habitats. These alluvial deposits were located between the Orange River and the rocky mountains seen in the background of both photographs.

Biology

Robertson's collections of T. rufescens include the following field notes:

SAM-HYM-C001039 - Nest entrance next to stone bound by half crater of sand on the one side and the stone on the other. Extensive seed stores in 1st 10cm of soil. Tried to dig down to central portion of colony but hit solid rock. Origin: ground nest, in soil next to rock, with entrance in open at base of rock. Food: seeds.

SAM-HYM-C001044 - Origin: ground nest. Method: saw hole/nest entrance. Habitat: flooplain, acacia.

SAM-HYM-C009186 – Foragers, open savanna on red clay soils with pointed termite mounds

Hawkes (2020) - A 2019 field study sampled 390 T. rufescens in 40 pitfall traps (from 10 transects of 20 traps 10m apart run for 6 days). Transects were placed in the major habitat types (riverine fringe, alluvial terrace gravels, alluvial fans, aeolian sands, Mispah soils and mountain slopes) of a diamond mine concession in northern Richtersveld National Park (Namakwa district, Northern Cape, South Africa). Tetramorium rufescens was found in five of the six habitats.

Castes

Nomenclature

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

  • rufescens. Tetramorium solidum st. rufescens Stitz, 1923: 163 (w.) NAMIBIA. Raised to species: Bolton, 1980: 249.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Description

Worker

Bolton (1980) - TL 4.0—5.1, HL 1.04-1.28, HW 0.92-1.18, CI 88-95, SL 0.78—0.88, SI 71-80, PW 0.62-0.80, AL 1.04-1.34 (12 measured).

Mandibles longitudinally rugose. Antennal clypeal margin with a small, narrow median notch or impression which may be difficult to see when the mandibles are fully closed. Frontal carinae extending back to a point about level with the anterior margins of the eyes by a weak ridge which is, however, usually more strongly developed than the remaining cephalic sculpture. Approximate points of termination of the frontal carinae marked by an erect hair on each side of the head. Antennal scrobes absent. Maximum diameter of eye 0:27-0:32, about 0-25-0-28 x HW. Propodeal spines long, narrow and acute, much longer than their basal width. Metapleural lobes low and rounded. Petiole in profile strongly nodiform, in dorsal view slightly broader than long and much broader behind than in front; anterior face of node quite narrowly rounded and the sides diverging strongly posteriorly. Postpetiole in dorsal view distinctly broader than long, with rounded sides, much broader than the petiole. Dorsum of head finely and quite densely longitudinally costulate or rugulose, the spaces between them with only faint, superficial ground-sculpture; glossy in large individuals. Dorsal alitrunk finely and densely reticulate-punctate, commonly with a few weak longitudinal costulae or rugulae on the promesonotum. Dorsal surfaces of petiole and postpetiole very weakly but densely reticulate-punctulate, in some this sculpture very feeble so that the surface appears merely roughened or lightly shagreened. Base of first gastral tergite lightly shagreened. Erect hairs absent from dorsal surfaces of alitrunk, pedicel segments and first gastral tergite; present on clypeus, first gastral sternite and segments behind the first. Dorsum of head with two pairs of hairs, one at the apices of the frontal carinae, the other on the occipital corners. Ventral surface of head with psammophore. Hind tibiae with appressed pubescence. Colour dull red, usually with the gaster darker in shade than the alitrunk and head.

Mbanyana et al. (2018) - (N = 13) HL 0.983–1.200 (1.065); HW 0.954–1.151 (1.021); SL 0.708–0.856 (0.772); EL 0.266–0.325 (0.291); PH 0.393–0.570 (0.460); PW 0.610–0.777 (0.678); WL 1.003–1.141 (1.101); PSL 0.167–0.236 (0.206); PTH 0.315–0.403 (0.348); PTL 0.275–0.325 (0.305); PTW 0.295–0.425 (0.343); PPH 0.315–0.418 (0.362); PPL 0.226–0.291 (0.259); PPW 0.369–0.521 (0.433); OI 27–30 (29); CI 91–100 (96); SI 73–81 (76); DMI 57–69 (62); LMI 36–50 (42); PSLI 16–23 (19); PeNI 46–61 (50); LPeI 78–100 (88) DPeI 97–127 (112); PpNI 59–75 (64); LPpI 59–77 (72); DPpI 154–188 (167); PPI 121–133 (127).

Type Material

Mbanyana et al. (2018) - Syntypes. Namibia: 3 pinned workers, Swakopmund, 12–19 Apr. 1911, W. Michaelsen leg. (Berlin Museum für Naturkunde der Humboldt-Universität: FOCOL2082 to FOCOL2084).

References

References based on Global Ant Biodiversity Informatics

  • Bolton B. 1980. The ant tribe Tetramoriini (Hymenoptera: Formicidae). The genus Tetramorium Mayr in the Ethiopian zoogeographical region. Bulletin of the British Museum (Natural History). Entomology 40: 193-384.
  • IZIKO South Africa Museum Collection
  • Koch F., and K. Vohland. 2004. Ants along a southern African transect - a basis for biodiversity change monitoring (Insecta, Hymenoptera, Formicidae). Zoosystematics and Evolution 80(2): 261-273.
  • Marsh A. C. 1985. Forager abundance and dietary relationships in a Namib Desert ant community. S. Afr. J. Zool. 20: 197-203.
  • 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. 1986. Checklist, biological notes and distribution of ants in the central Namib Desert. Madoqua 14: 333-344.
  • Mbanyana N. 2013. Taxonomy, phylogeny and biogeography of seed-harvesting ants in the Tetramorium solidum-group (Hymenoptera: Formicidae). Masters of Science in the Department of Botany and Zoology at Stellenbosch University 115 pages.
  • Mbanyana N., F. Hita Garcia, H. G. Robertson, and J. J. Le Roux. 2018. A taxonomic revision of seed harvester ants of the Tetramorium solidum group (Hymenoptera: Formicidae) in southern Africa. European Journal of Taxonomy 454: 1-59.
  • Robertson H. G. 2000. Formicidae (Hymenoptera: Vespoidea). Cimbebasia Memoir 9: 371-382.