Strumigenys origo

A common, widespread species. It occurs in mesic forests and has been collected in litter-samples, rotten wood and soil.

Identification
Bolton (2000) - A member of the scotti complex in the Strumigenys scotti-group. S. origo is a widespread and commonly collected species. Among the scotti-complex species which have the dorsum of the petiole node reticulate-punctate, origo can be distinguished by having: 1 Mesonotum with 3 pairs of erect hairs. 2 Pronotum with one pair of long erect hairs on central dorsum. 3 In profile ventral spongiform curtain of petiolar peduncle well developed, entire depth of curtain more or less greater than maximum diameter of eye. 4 Cephalic ground-pilosity erect or suberect.

See under Strumigenys glycon for further discussion.

Distribution based on Regional Taxon Lists
Malagasy Region: Madagascar.

Nomenclature

 *  origo. Strumigenys origo Fisher, in Bolton, 2000: 691, fig. 403 (w.q.) MADAGASCAR.

Worker
Holotype. TL 2.2, HL 0.50, HW 0.39, CI 78, ML 0.25, MI 49, SL 0.30, SI 78, PW 0.26, AL 0.54. Characters of scotti-complex. Mandibles in full-face view short, outer margins shallowly and evenly convex. Upper scrobe margin evenly and shallowly convex in full-face view, not bordered by a rim or flange, the eyes visible. Maximum diameter of eye slightly greater than maximum width of scape, with 4-5 ommatidia in longest row. Scape subcylindrical, curved and narrowed near base; hairs on leading edge slender, flattened or spoon-shaped apically. Cephalic dorsum densely clothed with erect to suberect filiform ground-pilosity. The upper scrobe margin fringed with sharply curved hairs which are similar in shape and size or slightly larger than those on the leading edge of the scape. Cephalic dorsum with 6 standing filiform hairs arranged in a transverse row of 4 close to the occipital margin and a more anteriorly situated pair. Pronotal humeral hair flagellate, dorsum with a central pair of standing hairs. Mesonotum with three pairs of standing filiform to narrowly remiform hairs: a pair on anterior margin, a pair situated central laterally, and a pair on posterior margin. Propodeum with one pair of short, fine, posteriorly curved hairs immediately anterior of propodeal spines. Ground-pilosity on dorsal alitrunk inconspicuous and more or less absent, consisting of short suberect to decumbent fine filiform hairs. Dorsum of alitrunk in outline convex anteriorly and more or less flat to shallowly convex posteriorly. Metanotal groove without a con spicuous impression. Anterior mesonotum with a narrow carina above the mesothoracic spiracle; mesopleural gland set in a small circular notch. Propodeal tooth triangular, lamellate, pointed apically, and subtended by a narrow lamella. Pronotal dorsum longitudinally striolate; mesonotal and propodeal dorsa reticulate-punctate. Sides of pronotum superficially longitudinally striolate. Pleurae and side of propodeum glassy smooth and peripherally punctulate. Postpetiole disc more or less smooth. In profile ventral spongiform tissue of petiolar peduncle a well developed curtain that is continuous along the base of the peduncle and equal or greater in depth than maximum diameter of eye. Basigastral costulae well developed and sharply defined, radiating on each side of a broad central clear area. Dorsal surface of petiole, postpetiole, and gaster with standing filiform hairs which are slightly thickened apically. Colour light brown.

Paratypes. TL 2.1, HL 0.49-0.51, HW 0.38-0.40, CI 74-82, ML 0.24-0.25, MI 48-50, SL 0.29-0.30, SI 73-79, PW 0.24-0.26, AL 0.51-0.54 (4 measured). As holotype.

Measurements of these specimens extend the range shown by the type-series; HL 0.41-0.55, HW 0.33-0.45, CI 75-83, ML 0.20-0.28, MI 46-53, SL 0.25-0.36, SI 74-86 (14 measured).

Type Material
Holotype worker, Madagascar: 1 0 km. NW Enakara, Ris. Andohahela, 24°34'S, 46°49'E, 430 m., 24.xi.1992, sifted litter (leaf mold, rotten wood, rainforest #522 (17)-4 (B. L. Fisher).

Paratypes. 4 workers and 2 queens (deal ate) with same data as holotype but coded (2)-3, (3)-2, (7)-2, (9)-5, (18)-25.

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.