Strumigenys chroa

Known from a range of forest habitats, this is a widespread species in Madagascar. Specimens have been collected from litter samples, rotten logs, foraging on vegetation and in a rotten stick.

Identification
Bolton (2000) - A member of the chroa complex in the Strumigenys scotti-group. A widely distributed but easily recognized member of the chroa-complex, this species is recognized by its lamellate upper scrobe margin, absence of a pronotal humeral hair and marginate ventral spongiform tissue of petiole.

Distribution based on Regional Taxon Lists
Malagasy Region: Madagascar.

Nomenclature

 *  chroa. Strumigenys chroa Fisher, in Bolton, 2000: 674, figs. 404, 420 (w.) MADAGASCAR.

Worker
Holotype. TL 3.2, HL 0. 80, HW 0.67, CI 84, ML 0.30, MI 38, SL 0.44, SI 66, PW 0.35, AL 0.81. Characters of chroa-complex. Mandibles almost straight and at full closure parallel except at base. Proximal preapical tooth on mandible confluent with lamella on inner margin that extends to base; in full-face view inner margin of lamella more or less straight. Upper scrobe margin a broad lamella, about as wide as scape. Eye small, with about 10 ommatidia in total. Hairs on leading edge of scape slender and filiform. Cephalic dorsum densely clothed with rows of curved narrow spatulate to spoon-shaped ground-pilosity, the upper scrobe margins fringed with a dense row of hairs which are the same shape and size as those on the dorsum. Cephalic dorsum with 6 simple standing hairs arranged in a transverse row of 4 close to the occipital margin and a more anteriorly situated pair. Pronotal humeral hair absent. Anterior margin of mesonotum with a pair of clavate to remiform hairs; posterior mesonotum with 2 additional pairs which are similar in shape to anterior pair but shorter. Ground-pilosity on alitrunk as on head. Dorsum of alitrunk in outline convex anteriorly and more or less flat posteriorly; posterior portion of mesonotum slightly depressed below the anterior margin of propodeum. Anterior mesonotum sharply marginate laterally, forming a convex lamellate extension above the mesothoracic spiracle. Propodeal tooth lam ell ate and confluent with the greatly expanded lamella for more than half its length. Alitrunk dorsum reticulate-punctate; pleurae mostly smooth and shiny, peripherally reticulate-punctate. Disc of postpetiole smooth and shiny, in dorsal view conspicuously broader than long. Ventral and lateral spongiform tissue of petiole and postpetiole greatly developed; ventral spongiform tissue of petiole marginate medially. Base of first gastral tergite with a continuous row of costulae. Dorsal surfaces of petiole, postpetiole and gaster with stout standing hairs which are thickened apically. Colour dull yellowish brown.

Paratypes. TL 3.1-3.3, HL 0.77-0.82, HW 0.68-0.70, CI 86-88, ML 0.29-0.31, MI 37-38, SL 0.41-0.46, SI 61-65, PW 0.33-0.37, AL 0.78-0.86 (3 measured). As holotype.

This material included workers from higher elevations that were larger than the type-series: HL 0.80-0.93, HW 0.64-0.77, CI 80-84, ML 0.31-0.36, MI 36-41, SL 0.43-0.52, SI 66-72 (11 measured).

Type Material
Holotype worker, Madagascar: Provo Toliara, southern Isoky-Vohimena Forest, 22°41'S, 44°50'E, 730 m., 21.i.1996 (S. Razajimandimby).

Paratypes. 1 worker with same data as holotype; 2 workers with same data but labeled sifted litter (leaf mold, rotten wood), dry forest and coded #1312 (9)-3, and (6)-4.

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)