Strumigenys dicomas

Judging from the more than one hundred collections of this ant, it nests in dead wood on the ground. It has been found in rotten logs, stumps and a downed stick, in addition to having been found in many litter samples.

Identification
Bolton (2000) - The only member of the Strumigenys koningsbergeri-group from the Malagasy region. S. dicomas is widely distributed but easily recognized. In the Malagasy region it is the only species with the mandible shape and dentition as described below.

Distribution based on Regional Taxon Lists
Afrotropical Region: Comoros. Malagasy Region: Madagascar, Mayotte.

Nomenclature

 *  dicomas. Strumigenys dicomas Fisher, in Bolton, 2000: 655, figs. 394, 416 (w.q.) MADAGASCAR.

Worker
Holotype. TL 3.6, HL 1.01, HW 0.93, CI 93, ML 0.48, MI 47, SL 0.63, SI 67, PW 0.42, AL 0.86. With the above characters and the following. Outer margins of mandibles shallowly convex in full-face view. Upper scrobe margin bordered by a conspicuous laminate rim or flange throughout its length; eyes partially visible in full-face view. Leading edge of scape with a row of slender hairs which are slightly flattened or spoon-shaped apically. Cephalic dorsum clothed with inconspicuous small curved spatulate to narrowly spoon-shaped ground-pilosity; the upper scrobe margin fringed with hairs which are similar in shape and size as those on the dorsum; apicoscrobal hair absent. Cephalic dorsum with 6 simple standing hairs arranged in a transverse row close to the occipital margin; many paratypes have a more anteriorly situated pair near the highest point of the vertex. Dorsum of head reticulate-punctate, middorsum rugulose in larger specimens. Mesonotum with a single pair of stout standing hairs situated on anterior margin. Propodeum without a 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. Dorsolateral margin of posterior pronotum bluntly marginate. Anterior mesonotum with a distinct narrow carina above the mesothoracic spiracle. Propodeal spine long and slender, recurved, especially near the apex; propodeal lamella absent. Alitrunk dorsum reticulate-punctate; lateral margins of pronotum rugulose; pleurae more or less smooth centrally with peripheral reticulate-punctate sculpture. Petiole node in dorsal view finely reticulate-punctate, exposed area of cuticle slightly broader than long. Postpetiole superficially reticulate-punctate. Spongiform appendages of petiole weakly developed, with a narrow ventral curtain. Postpetiole with small but distinct lateral and ventral spongiform lobes. Basigastral costulae short and distinct; gaster smooth and shiny when clean. Dorsal surfaces of petiole, postpetiole, and gaster with stout standing hairs which are swollen apically. Colour dull yellow to light medium brown.

Paratypes. TL 3.6-4.2, HL 1.00-1.17, HW 0.91-1.11, CI 90-95, ML 0.48-0.55, MI 46-49, SL 0.62-0.70, SI 63-68, PW 0.41-0.49, AL 0.81-1.02 (9 measured). As holotype.

The non-paratypic material shows greater size variation than the type-series alone: HL 0.86-1.09, HW 0.75-1.04, CI 87-95, ML 0.41-0.52, MI 42-50, SL 0.53-0.68, SI 61-75 (12 measured), but otherwise matches all diagnostic characters.

Type Material
Holotype worker, Madagascar: 9.2 km. WSW Befingotra, Res. Anjanaharibe-Sud, 14°45'S, 49°28'E, 1200 m., 9.xi.1994, sifted litter (leaf mold rotten wood), montane rainforest #1192 (12)-14 (B. L. Fisher).

Paratypes. 9 workers and 2 queens (dealate) with same data as holotype but coded (3)-9, (23)-9, (24)-9, (24)-10, (29)-8, (36)-9, (40)-4, (50)-10, (L. O.)-10.

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.
 * Fisher, B. 2002. Ant diversity patterns along an elevational gradient in the Reserve Speciale de Manongarivo, Madagascar. in Gautier, L. and S.M. Goodman, editors, Inventaire Florestique et Faunistique de la Reserve Speciale de Manongarivo (NW Madagascar)