Strumigenys emarginata

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Strumigenys emarginata
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Strumigenys
Species: S. emarginata
Binomial name
Strumigenys emarginata
Mayr, 1901

Strumigenys emarginata casent0235993 p 1 high.jpg

Strumigenys emarginata casent0235993 d 1 high.jpg

Specimen Labels

All Strumigenys are specialist predators but foragers of S. emarginata can also leave the forest litter and climb plants to exploit their nectar as well as aphid honeydew (Dejean 1991). The use of honeydew was also observed in Strumigenys yaleogyna.

Identification

Bolton (2000) - The concept of this species has changed since Bolton (1983). At that time all the available material that now constitutes the five species of the emarginata-complex was included under a single species, emarginata, following the taxonomy of Brown (1953a). The acquisition of additional material and critical re-assessment of older specimens has led to its subdivision into the species recognised here. Bolton (2000) - A member of the emarginata complex in the Strumigenys emarginata group. Characters of emarginata-complex. All hairs on dorsum of head spoon-shaped, without simple hairs close to the occipital margin . All hairs on promesonotum short and spoon-shaped, without 3-4 pairs of standing longer hairs on the mesonotum. Pleurae and side of propodeum reticulate to finely reticulate-punctate everywhere. Pronotal dorsum weakly sculptured with longitudinal striolae or costulae. S ide of pronotum weakly but quite distinctly sculptured . Propodeal dorsum reticulate-punctate.

Within the emarginata-complex emarginata and Strumigenys subsessa form a species-pair characterised by a complete lack of standing hairs on the promesonotal dorsum; all hairs on this sclerite are spoon-shaped and markedly curved. The other three species (Strumigenys exunca, Strumigenys noara, Strumigenys robertsoni) have varying pilosity but all have 3-4 pairs of conspicuous standing hairs on the mesonotum.

Keys including this Species

Distribution

Latitudinal Distribution Pattern

Latitudinal Range: 2.366666555° to -29.66667°.

   
North
Temperate 		North
Subtropical 		Tropical South
Subtropical 		South
Temperate

Distribution based on Regional Taxon Lists

Afrotropical Region: Angola, Burundi, Ghana, Ivory Coast, South Africa (type locality), Togo, Zimbabwe, Zimbabwe.

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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Biology

In addition to predation, foragers also exploit the extrafloral nectaries of Urena lobata as well as green colored Aphididae (Dejean 1991).

Life History Traits

  • Mean colony size: 199 (Dejean, 1982; Beckers et al., 1989)
  • Foraging behaviour: solitary forager

Castes

Nomenclature

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

  • emarginata. Strumigenys emarginata Mayr, 1901b: 26 (w.) SOUTH AFRICA. Combination in S. (Trichoscapa): Santschi, 1913b: 257; in S. (Cephaloxys): Wheeler, W.M. 1922a: 919; Emery, 1924d: 324; in Smithistruma: Brown, 1948e: 105; in Pyramica: Bolton, 1999: 1673; in Strumigenys: Baroni Urbani & De Andrade, 2007: 119. See also: Brown, 1953g: 126; Bolton, 1983: 291; Bolton, 2000: 301.

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

Description

Worker

Bolton (2000) - TL 2.4-2.5, HL 0.64-0.66, HW 0.40-0.42, CI 62-65, ML 0.11-0.12, MI 17-18, SL 0.32-0.34, SI 78-83, PW 0.26-0.28, AL 0.66-0.68 (8 measured).

Bolton (1983) - Mandibles with a high truncated triangular basal lamella (concealed by clypeus when mandibles are closed), followed without a diastema by a row of 5 relatively large teeth, 2 slightly smaller teeth and 4 small denticles before the apical tooth. Anterior clypeal margin in full-face view varying from almost transverse to evenly shallowly concave. Lateral margins of clypeus slightly convergent anteriorly, the anterolateral clypeal angles bluntly rounded. Anterior clypeal margin fringed by a series (usually of 6-8) broad scale-like hairs, the lateral margins and corners with an unbroken sequence of long fringing hairs which are flattened to spoon-shaped and which are curved anteriorly on the sides and medially on the anterolateral corners. Dorsum of clypeus and of head behind clypeus with numerous spoon-shaped curved hairs which appear scale-like in full-face view. Sometimes the occipital region with a few simple curved hairs present but these variable in number and degree of development; flagellate hairs never developed. With the head in full-face view the upper scrobe margins and occipital lobes laterally fringed with anteriorly curved spoon-shaped hairs, the head long and narrow (CI < 65) and with the eyes plainly visible, projecting beyond the level of the upper scrobe margins. Eyes larger than in any other other known Afrotropical species, their maximum diameter 0.21-0.25 X HW, greater than the maximum width of the scape. Scapes long (SI >70), narrow basally, shallowly curved at about the basal third and broadest just distal to this where the leading edge is bluntly subangulate. Leading edges of scapes with projecting flattened to spoon-shaped strong hairs. With the head in profile the dorsum very shallowly impressed between clypeus and vertex, highest at the vertex and sloping down posteriorly to the occipital margin. Dorsum of head finely and densely reticulate-punctulate to granular everywhere. With the alitrunk in profile the central portion of the mesonotum extremely feebly impressed. The metanotal groove not impressed but sometimes represented as a line. Propodeal teeth long and narrow, often slightly upcurved and sometimes weakly sinuate along their length. Infradental lamellae narrow and inconspicuous down the propodeal declivity. Sides of alitrunk not marginate, the pronotal dorsum without a median longitudinal ridge or carina, the pronotal humeri evenly rounded. Pilosity of dorsal alitrunk variable, usually with curved spoon-shaped hairs on pronotum and anterior mesonotum but behind this the hairs longer and finer, subspatulate to cylindrical and simple, and often with one or two pairs suberect to erect. Variation from this more or less median position is shown on the one hand in samples where all the hairs are spoon-shaped and merely vary in size (becoming larger posteriorly), there being no subspatulate or simple hairs developed; and on the other hand by the suppression of the spoon-shaped hairs and their replacement everywhere by simple suberect to erect pilosity. Flagellate hairs never present. Pronotal dorsum very finely and faintly striate, this sculpture sometimes virtually effaced. Mesonotum and usually also propodeal dorsum finely punctulate; sides of alitrunk punctulate. Spongiform appendages of petiole and postpetiole massively developed in profile. In dorsal view the petiole with a spongiform strip on its posterior margin which is strongest posterolaterally. Anterior margin of postpetiole in dorsal view with a spongiform strip but the sides without. The broadly convex posterior margin of the postpetiole with spongiform tissue very broadly developed at the sides but strongly indented or even interrupted medially, usually the posterior margin of the spongiform material touching the margin of the postpetiolar disc centrally. Petiole dorsum very faintly punctulate to smooth, the disc of the postpetiole always unsculptured and smooth. Dorsal surfaces of petiole, postpetiole and first gastral tergite with elongate simple curved hairs present. First gastral tergite impressed mediobasally, usually sharply so, the impressed area usually including both the central portion of the basal lamellar band of the tergite and the tergal area immediately behind it. Basigastral costulae absent from the impressed area, radiating from each side of it; gaster otherwise unsculptured. Colour yellow to medium brown, sometimes the gaster distinctly darker than the head and alitrunk.

Type Material

Bolton (1983) - Syntype workers, SOUTH AFRICA: Port Elizabeth (H. Brauns) (Naturhistorisches Museum Wien, Vienna) [examined].

References

References based on Global Ant Biodiversity Informatics

  • Arnold G. 1917. A monograph of the Formicidae of South Africa. Part III. Myrmicinae. Annals of the South African Museum. 14: 271-402.
  • Bolton B. 1983. The Afrotropical dacetine ants (Formicidae). Bulletin of the British Museum (Natural History). Entomology 46: 267-416.
  • Bolton, B. 2000. The Ant Tribe Dacetini. Memoirs of the American Entomological Institute 65
  • Brown W. L. 1964. The ant genus Smithistruma: a first supplement to the world revision (Hymenoptera: Formicidae). Transactions of the American Entomological Society 89: 183-200.
  • Brown W. L., Jr. 1953. Revisionary studies in the ant tribe Dacetini. Am. Midl. Nat. 50: 1-137.
  • CSIRO Collection
  • IZIKO South Africa Museum Collection
  • Lévieux J. 1972. Les fourmis de la savane de Lamto (Côte d'Ivoire): éléments de taxonomie. Bulletin de l'Institut Fondamental d'Afrique Noire. Série A. Sciences Naturelles 34: 611-654.
  • Wheeler W. M. 1922. Ants of the American Museum Congo expedition. A contribution to the myrmecology of Africa. VIII. A synonymic list of the ants of the Ethiopian region. Bulletin of the American Museum of Natural History 45: 711-1004
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