Strumigenys dextra

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Strumigenys dextra
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Strumigenys
Species: S. dextra
Binomial name
Strumigenys dextra
Brown, 1954

Strumigenys dextra casent0900628 p 1 high.jpg

Strumigenys dextra casent0900628 d 1 high.jpg

Specimen Labels

Known from more than twenty collections, all from wet forest litter samples.

Identification

Bolton (1983, 2000) - A member of the dextra complex in the Strumigenys arnoldi-group. In the dextra-complex three other species beside dextra have lost the distal preapical tooth of the left mandible, Strumigenys irrorata, Strumigenys katapelta and Strumigenys paranax. The first of these is distinguished from dextra and the rest by also lacking the distal preapical tooth on the right mandible so that both blades have only a single preapical tooth. S. katapelta is the only species of the four which possesses intercalary teeth between the spiniform teeth of the apical forks, and paranax is easily separated from dextra by its possession of a straight stout projecting hair at the humeri where dextra has a long fine flagellate hair present.

Elsewhere in the genus Strumigenys bernardi, Strumigenys sarissa and Strumigenys londianensis also have only a single preapical tooth on the left mandible, but in all of these there is a large and very distinct preocular notch present.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Afrotropical Region: Angola, Cameroun, Central African Republic, Democratic Republic of Congo, Equatorial Guinea, Gabon, Kenya, Uganda (type locality).

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Strumigenys were once thought to be rare. The development and increased use of litter sampling methods has led to the discovery of a tremendous diversity of species. Many species are specialized predators (e.g. see Strumigenys membranifera and Strumigenys louisianae). Collembola (springtails) and other tiny soil arthropods are typically favored prey. Species with long linear mandibles employ trap-jaws to sieze their stalked prey (see Dacetine trap-jaws). Larvae feed directly on insect prey brought to them by workers. Trophallaxis is rarely practiced. Most species live in the soil, leaf litter, decaying wood or opportunistically move into inhabitable cavities on or under the soil. Colonies are small, typically less than 100 individuals but in some species many hundreds. Moist warm habitats and micro-habitats are preferred. A few better known tramp and otherwise widely ranging species tolerate drier conditions. Foraging is often in the leaf litter and humus. Workers of many species rarely venture above ground or into exposed, open areas. Individuals are typically small, slow moving and cryptic in coloration. When disturbed individuals freeze and remain motionless. Males are not known for a large majority of species.

Castes

Nomenclature

The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • dextra. Strumigenys dextra Brown, 1954k: 27 (w.) UGANDA. See also: Bolton, 1983: 368; Bolton, 2000: 592.

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

Description

Worker

Bolton (1983) - TL 1.6-1.8, HL 0.41-0.47, HW 0.31-0.34, CI 71-77, ML 0.16-0.19, MI 38-42, SL 0.22-0.25, SI 68-75, PW 0.21-0.24, AL 0.40-0.48 (10 measured).

Mandibles relatively slender, shallowly and evenly curved along the outer margins. Apical fork of each mandible of two teeth, without intercalary teeth or denticles. Preapical armament of left mandible of a single tooth, the right mandible with 2 preapical teeth. Upper scrobe margins concealing the eyes in full-face view. Eyes small, with only 3--5 ommatidia, the maximum diameter of the eye distinctly less than the maximum width of the scape. Pre ocular notch absent, the ventral surface of the head without a transverse preocular groove or impression on each side. Antennal scape shallowly curved basally, somewhat expanded in the median third, the leading edges with a row of apically curved narrow spoon-shaped hairs. Ground-pilosity of cephalic dorsum reduced, consisting of a few inconspicuous small spatulate haits. Upper scrobe margins with a triple row of larger narrowly spoon-shaped hairs. Dorsum of head with 6 standing hairs arranged in a transverse row of 4 close to the occipital margin and a more anteriorly situated pair. Pronotal humeri each with a single fine flagellate hair. Mesonotum with a single pair of standing stout hairs which are clavate apically. Ground-pilosity of dorsal alitrunk of inconspicuous narrowly spatulate hairs like those on dorsum of head. In profile the mesonotum feebly or not depressed behind the level of the standing hairs. Propodeal teeth short and subtended by moderately developed infradental lamellae. Sides of pronotum almost smooth to weakly longitudinally rugulose. Pleurae and sides of propodeum smooth except for weak peripheral punctures. Dorsal alitrunk with sparse widely separated longitudinal rugulae on pronotum, the spaces between the rugulae smooth or with vestiges of superficial sculpture. Remainder of dorsal alitrunk reticulate-punctate. Dorsum of petiole node punctate, the postpetiole smooth. Spongiform appendages of pedicel segments only moderately developed. In profile the petiole with a narrow ventral strip and small lateral appendage on the node. Ventral spongiform lobe of postpetiole equal to or Slightly smaller than the exposed area of the postpetiolar disc in profile. Basigastral costulae short but sharply defined, arising across the width of the first tergite basally, not radiating on each side of a broad central clear area. Dorsal surfaces of petiole, postpetiole and gaster with stout standing hairs which are narrowly clavate apically. Colour dull yellow.

Type Material

Bolton (1983) - Holotype and paratype workers, UGANDA: 5 miles (8 km) N. Kamapala, Kawanda Exp. Sta., 15.ii.1949, no. SS 30, soil sample under elephant grass (G. Salt) (Museum of Comparative Zoology) [examined].

References