Strumigenys relahyla

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Strumigenys relahyla
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Strumigenys
Species: S. relahyla
Binomial name
Strumigenys relahyla
Bolton, 1983

Strumigenys relahyla casent0900604 p 1 high.jpg

Strumigenys relahyla casent0900604 d 1 high.jpg

Specimen Labels

There are two known collections of this species: "riverbank" type material and a rainforest litter-sample.

Identification

Bolton (2000) - A member of the Strumigenys scotti-group. Outer margin of mandible convex, broadest at about the midlength. Distal preapical tooth on left mandible well developed, almost as broad basally as the proximal and at least half the length of the proximal. Preocular notch small but distinct. Curved hairs that fringe upper scrobe margin broadly spatulate to spoon-shaped, much larger than those on leading edge of scape.

Bolton (1983) - Size range of non-paratypic material is HL 0.50-0.53, HW 0.36-0.41, CI 72-77, ML 0.22-0.24, MI 44-46, SL 0.25-0.27, SI 66-69 (10 measured). Resembling the holotype but with variable colour ranging from uniform pale brown, through medium brown with the gaster darker, to uniform dark brown. The size of the ventral spongiform lobe of the postpetiole shows some variation but is always at least as large as the exposed area of the disc in profile. The distal pre apical teeth of the mandibular blades are usually as described above but in a few samples they are shorter than the distance separating the bases of the two pre apical teeth. S. relahyla belongs to a small aggregation of species in which the preocular notch is present but small, and is not extended onto the ventral surface of the head as a groove or impression. Of the species thus defined relahyla is distinguished by a lack of specialized characters when compared to the others. In Strumigenys totyla the pronotal humeri lack flagellate hairs; in Strumigenys xenohyla the scape hairs are very large and spoon-shaped, like those on the upper scrobe margins; in Strumigenys adrasora the spongiform appendages of the petiole and postpetiole are much reduced; in Strumigenys rukha the spongiform appendages are strongly developed; and in Strumigenys dyshaula the head is more narrowly and deeply impressed at the occipital margin.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Afrotropical Region: Angola (type locality), Cameroun, Democratic Republic of Congo.

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.

  • relahyla. Strumigenys relahyla Bolton, 1983: 386, figs. 57, 74 (w.) ANGOLA. See also: Bolton, 2000: 610.

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 2.0, HL 0.56, HW 0.41, CI 73, ML 0.24, MI 43, SL 0.28, SI 68, PW 0.26, AL 0.52.

Apical fork of mandibles with 2 spiniform teeth, without intercalary teeth or denticles. Preapical armament of 2 teeth on each blade, the proximal longest, the distal about as long as, or slightly longer than, the distance separating the bases of the preapical teeth. Outer margins of mandibles shallowly convex in full-face view and the occipital margin broadly concave. Upper scrobe margins with a very narrow bordering rim or flange, the eyes mostly visible in full-face view. Maximum diameter of eye about 0.15 X HW, slightly greater than the maximum width of the scape. Preocular notch present, narrow but distinct, the anterior portion of the eye not detached from the side of the head and the preocular notch not extended onto the ventral surface of the head as a transverse groove or impression. Antennal scapes feebly bent basally, broadened in the middle third, the leading edge equipped with a row of narrow spoon-shaped ham which are smaller than those fringing the upper scrobe margin. Cephalic ground-pilosity of inconspicuous small spatulate hairs, the upper scrobe margins with a projecting row of large anteriorly curved 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. Dorsum of head finely reticulate-punctate. Pronotal humeri each with a single long fine flagellate hair. Mesonotum with a single pair of stout standing hairs. Ground-pilosity of dorsal alitrunk of fine spatulate hairs similar to those on the head. Posterior portion of mesonotum depressed behind the level of the pair of hairs, with a shallow transverse impression immediately behind the descending slope. Remainder of mesonotum and dorsum of propodeum convex. Metanotal groove forming a transverse line on the dorsum. Propodeal teeth lameliate, confluent for slightly more than half their length with the conspicuous infradental lamellae. Sides of alitrunk unsculptured except for some faint scratch-like costulae on the pronotum and some feeble peripheral punctulation on the pleurae and propodeum. Pronotal dorsum longitudinally finely costulate-rugulose, the remainder of the alitrunk punctate. Dorsum of petiole node shallowly punctate, the postpetiole smooth. Spongiform appendages of pedicel segments moderately developed, the petiole with a thin ventral strip and small lateral lobe. Ventral spongiform lobe of postpetiole larger than the lateral lobe and larger than the exposed area of the postpetiolar disc in profile. Basigastral costulae relatively sparse, without secondary costulae arising between those which have their origins on the basal gastral strip. Petiole, postpetiole and gaster dorsally with standing hairs. Colour yellowish brown, the gaster darker.

Paratypes. TL 1.9-2.0, HL 0.54-0.56, HW 0.40-0.41, CI 73-76, ML 0.23-0.24, MI 43-44, SL 0.26-0.28, SI 65-68, PW 0.25-0.27, AL 0.51-0.54 (4 measured). As holotype.

Type Material

Holotype worker, Angola: Duque de Braganca Falls, 12.iii.1972, riverbank (P. Hammond) (The Natural History Museum). Paratypes. 4 workers with same data as holotype (BMNH; Museum of Comparative Zoology).

References