Strumigenys actis

S. actis is a fairly common species, having been found in a range of forest habitats and even in a park garden. It has been collected from forest litter, in rotten downed wood of various types (rotten log, stump, etc.), and under moss and rocks. Foragers have also been collected from vegetation.

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 actis 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 1 pair of erect hairs, on anterior margin.

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

Distribution based on Regional Taxon Lists
Malagasy Region: Madagascar.

Nomenclature

 *  actis. Strumigenys actis Fisher, in Bolton, 2000: 648 (w.) MADAGASCAR.

Worker
Holotype. TL 3.4, HL 0.88, HW 0.70, CI 80, ML 0.46, MI 52, SL 0.59, SI 84, PW 0.36, AL 0.85. Characters of chilo-complex. Mandibles almost straight and at full closure parallel. Apical fork of mandible subtended by a third, shorter spiniform tooth, the fork effectively 3-dentate; without intercalary teeth or denticles. Preapical teeth absent. 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. 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-shaped ground-pilosity; the upper scrobe margin without a row of hairs. Cephalic dorsum with 4 simple standing hairs arranged in a transverse row close to the occipital margin. Dorsum of head reticulate-punctate. Mesonotum with a single pair of stout standing hairs situated on anterior margin. 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 and 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 disc reticulate-punctate. Spongiform appendages of petiole weakly developed. Postpetiole with small but distinct lateral and ventral spongiform lobes. Basigastral costulae fine across base of gaster without a central clear area; gaster smooth and shiny where clean. Dorsal surfaces of petiole often with a pair of short posteriorly projecting hairs; postpetiole 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.

Measurements of this material extend the range shown by the type-series: TL 3.3-3.9, HL 0.86-1.01, HW 0.65-0.86, CI 75-92, ML 0.44-0.54, MI 49-59, SL 0.56-0.70, SI 79-86, PW 0.34-0.41, AL 0.80-0.99 (9 measured).

Type Material
Holotype worker, Madagascar: 43 km. S Ambalavao, Res. Andringitra, 22°14'S, 47°00'E, 825 m., 5.x.1993, sifted litter (leaf mold rotten wood), rainforest #747 (14)-8 (B. L. Fisher).

References based on Global Ant Biodiversity Informatics

 * Blaimer B. B., S. G. Brady, T. R. Schultz, and B. L. Fisher. 2015. Fucntional and phylogenetic approaches reveal the evolution of diversity in a hyper diverse biota. Ecography 38: 001-012.
 * 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.