Strumigenys quadrua

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Strumigenys quadrua
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Strumigenys
Species: S. quadrua
Binomial name
Strumigenys quadrua
Bolton, 2000

Strumigenys quadrua casent0900472 p 1 high.jpg

Strumigenys quadrua casent0900472 d 1 high.jpg

Specimen Labels

Nothing is known about the biology of Strumigenys quadrua.

Identification

Bolton (2000) - A member of the Strumigenys silvestrii-group. Despite the fact that both specimens are poorly mounted and have apparently suffered some abrasion, quadrua is easily recognised because of its 4-segmented antennae and extremely reduced preapical dentition. A few specimens of species in this group may show an apparently 5-segmented antenna, caused by the partial fusion of funicular segments 2 and 3, but in these individuals the fusion segment remains conspicuous, and they have at least one distinct preapical tooth on the mandible.

In the Neotropical Strumigenys fauna only the tramp species emmae also has 4-segmented antennae. The characters given in the key and under the species-group diagnoses quickly differentiate Strumigenys emmae from quadrua.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Neotropical Region: Brazil (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 Online Catalogue of the Ants of the World.

  • quadrua. Strumigenys quadrua Bolton, 2000: 557 (w.) BRAZIL.

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

Description

Worker

Holotype. TL 1.5, HL 0.38, HW 0.30, CI 79, ML 0.19, MI 50, SL 0.21, SI 70, PW 0.21, AL 0.40. Preapical armament of mandible of two minute vestigial denticles at least on right mandible, one just proximal and the other just distal of the mandibular midlength; denticles only properly visible at high magnification and with correct lighting so that in effect the mandible apparently lacks preapical dentition. Antenna with only 4 segments. Scape with an obtuse but abrupt subbasal bend, the hairs on the leading edge that curve toward the base of the scape longer than the maximum width of the scape. Ground-pilosity of head inconspicuous, simple to very narrowly linear-spatulate. Apicoscrobal hair apparently absent but specimens poorly mounted so this hair may have been dislodged. Pronotal humeral hair weakly flagellate; hairs on first gastral tergite flagellate. Sides of alitrunk smooth. Ventral surface of petiole without spongiform tissue; lateral spongiform lobe of petiole vestigial, scarcely more expanded than the posterior collar. Lamella on propodeal declivity narrow, angulate basally but not dentiform. Petiole node in dorsal view broader than long; disc of postpetiole and first gastral tergite smooth. Basigastral costulae at maximum longer than disc of postpetiole.

Paratype. TL 1.5, HL 0.38, HW 0.31, CI 82, ML 0.18, MI 47, SL 0.20, SI 65, PW 0.21, AL 0.41.

Type Material

Holotype worker, Brazil: Bahia, Ilheus, CEPEC-area Zoolog., km. 22 Ilheus-ltab., x.1986, no. 30 (J. Delabie) (Museu de Zoologia da Universidade de Sao Paulo).

Paratype. 1 worker with same data as holotype (The Natural History Museum).

References

  • Bolton, B. 2000. The ant tribe Dacetini. Memoirs of the American Entomological Institute. 65:1-1028.