Strumigenys ampyx

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

Strumigenys ampyx casent0005484 profile 1.jpg

Strumigenys ampyx casent0005484 dorsal 1.jpg

Specimen labels

The type material was collected from a twig nest found in a forest.

Identification

Bolton (2000) - A member of the chilo complex in the Strumigenys grandidieri-group. Among the Malagasy species that have the mandibular apical fork subtended by a shorter third tooth ampyx is easily isolated by the following characters:

1 Upper scrobe margin ends, or at least becomes extremely indistinct, at about the level of the eye; when viewed in profile, upper scrobe margin extends posteriorly across dorsal apex of vertical preocular groove of side of head; preocular groove meets and is interrupted by the upper scrobe margin before reaching the cephalic dorsum.

2 Mesonotum with 2 pairs of erect hairs on anterior margin.

3 Cephalic dorsum with a transverse row of six erect hairs immediately in front of occipital margin.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Malagasy Region: Madagascar (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

Worker

Nomenclature

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

  • ampyx. Strumigenys ampyx Fisher, in Bolton, 2000: 649 (w.) MADAGASCAR.

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 2.6, HL 0.76, HW 0.64, CI 85, ML 0.42, MI 55, SL 0.52, SI 81, PW 0.33, AL 0.76. Characters of chilo-complex. Mandibles almost straight and at full closure parallel. Apical fork of mandible sub tended by a third, shorter spiniform tooth, the fork effectively 3-dentate; without intercalary teeth or denticles. Preapical teeth absent but a small spiniform denticle may occur immediately proximal of apicodorsal tooth on right mandible. Upper scrobe margin end s, or at least becomes extremely indistinct, at about the level of the eye; when viewed in profile, upper scrobe margin extends posteriorly across dorsal apex of vertical preocular groove of side of head; preocular groove meets and is interrupted by the upper scrobe margin before reaching the cephalic dorsum. Eye large, convex, and plainly visible in full-face view. Scape long and slender, approximately straight, the leading edge with a row of slender hairs which are slightly flattened or spoon-shaped apically. Cephalic dorsum densely clothed with curved spoon-shape ground-pilosity; the upper scrobe margin without a row of hairs. Cephalic dorsum with 6 simple standing hairs arranged in a transverse row close to the occipital margin. Dorsum of head reticulate-punctate. Pronotum without standing hairs. Mesonotum with two pairs of stout standing remiform to narrowly clavate hairs: a pair on anterior margin and a posteriorly situated pair. Propodeum with one pair of short, fine, posteriorly curved hairs immediately anterior of propodeal spines. Ground-pilosity on alitrunk as on head but sparser. With the alitrunk in profile the posterior portion of the mesonotum sharply depressed, the metanotal groove represented by a shallow impression. Pronotal humeri rounded. Lateral margin of posterior pronotum bluntly marginate. Anterior mesonotum with a narrow carina above the mesothoracic spiracle. Propodeal tooth long, slender, almost spiniform; propodeal lamella absent. Alitrunk dorsum and sides reticulate-punctate. Petiole node in dorsal view reticulate-punctate and much longer than broad. Postpetiole reticulate-punctate. Spongiform appendages of petiole weakly developed. Postpetiole with small but distinct lateral and ventral spongiform lobes. Basigastral costulae fine and superficial across base of gaster without a central clear area; gaster smooth and shiny where clean. Dorsal surfaces of petiole and postpetiole each with a pair of posteriorly projecting stout hairs; gaster with stout standing hairs which are weakly swollen apically. Colour dull yellow to light medium brown.

Paratypes. TL 2.9-3.1, HL 0.74-0.79, HW 0.62-0.67, CI 83-87, ML 0.40-0.43, MI 53-57, SL 0.50-0.55, SI 78-85, PW 0.32-0.35, AL 0.72-0.77 (8 measured). As holotype.

Measurements of this material extend the range shown by the type-series: HL 0.80-0.81, HW 0.66- 0.73, CI 83-89, ML 0.43-0.46, MI 53-57, SL 0.54-0.57, SI 77-82 (3 measured).

Type Material

Holotype worker, Madagascar: Isalo Nat. Park, Ranohira Canion de Singe forest, 800 m., 22°29'S, 45°33'E, 17.ii.1993, twig nest, #1397w (E. Rajeriarison) (Museum of Comparative Zoology).

Paratypes. 10 workers with same data as holotype but coded: #.13962, .13965, .13968, .13970, .13977 (The Natural History Museum, South African Museum).

References

  • Fisher, B.L. 2000. The Malagasy fauna of Strumigenys. Pp. 612-696 in: Bolton, B. 2000. The ant tribe Dacetini. Memoirs of the American Entomological Institute. 65:1-1028. (page 649, worker described)