Strumigenys ampyx

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.

Distribution based on Regional Taxon Lists
Malagasy Region: Madagascar.

Nomenclature

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

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).

Paratypes. 10 workers with same data as holotype but coded: #.13962, .13965, .13968, .13970, .13977.

References based on Global Ant Biodiversity Informatics

 * Bolton, B. 2000. The Ant Tribe Dacetini. Memoirs of the American Entomological Institute 65
 * Fisher B. L. 2003. Formicidae, ants. Pp. 811-819 in: Goodman, S. M.; Benstead, J. P. (eds.) 2003. The natural history of Madagascar. Chicago: University of Chicago Press, xxi + 1709 pp.