Strumigenys hiroshimensis

A rare species found on the floor of broadleaf forests and nesting in the soil (Ogata & Onoyama, 1998).

Identification
A member of the Strumigenys circothrix-group.

Bolton (2000) - S. hiroshimensis: there is a single spoon-shaped hair on the leading edge of the scape (distal of the subbasal angle) that is curved toward the base of the scape; dorsum of the petiole node is without apically thickened to spatulate standing hairs; hairs on the first gastral tergite are simple; fully closed mandibles are as long as maximum length of clypeus; in dorsal view maximum width of lateral spongiform tissue on one side of postpetiole disc is broader than the dorsal width of the hind femur.

Strumigenys circothrix: has all hairs on the scape distal of the subbasal angle curved toward the apex of the scape; dorsum of the petiole node has 2 pairs of apically thickened to spatulate standing hairs; hairs on the first gastral tergite are apically thickened to clavate; fully closed mandibles are slightly shorter than maximum length of clypeus; in dorsal view maximum width of lateral spongiform tissue on one side of postpetiole disc is narrower than the dorsal width of the hind femur.

Distribution based on Regional Taxon Lists
Oriental Region: Taiwan. Palaearctic Region: Japan.

Nomenclature

 *  hiroshimensis. Smithistruma hiroshimensis Ogata & Onoyama, 1998: 281, figs. 5, 6 (w.) JAPAN. Combination in Pyramica: Bolton, 1999: 1673; in Strumigenys: Baroni Urbani & De Andrade, 2007: 121. See also: Bolton, 2000: 411.

Worker
TL: 1.35 mm; HL: 0.53 mm; HW: 0.42 mm; CI: 78; ML: 0.13 mm; MI: 25; SL: 0.25 mm; SI: 60; PW: 0.25 mm; WL: 0.57 mm. (1 measured).

Head longer than wide, with roundly convex sides posteriorly; posterior border emarginate with low occipital carina. Mandibles as long as clypeus in full face view; dentition not observed. Clypeus with straight anterior margin and rounded corners, and fringed with spatulate hairs. Antennae 6-segmented; outer margin of scape with angulate elbow at basal ¼; apical segment longer than the rest of funiculus. Eyes small, consisting of 4 facets.

Pronotum angulate anteriorly, but not posteriorly. Propodeum with infradental lamella posteriorly. Petiolar node broader than long in dorsal view. Spongiform appendages of postpetiole well developed, the width of each side thicker than the dorsal width of hind femur in dorsal view.

Head and mesosoma covered with suborbicular hairs. Spatulate hairs present on pronotal humeri, mesonotum, but absent on petiole, postpetiole and gaster.

Lateral surface of mesothorax, propodeum, and whole gaster except for basitergum of 1st segment smooth and shining; the rest of body reticulate-punctate. Body color reddish brown.

Bolton (2000) - TL 2.0, HL 0.55, HW 0.41, CI 75, ML 0.13, MI 24, SL 0.28, SI 68, PW 0.25, AL 0.54. Extremely closely related to circothrix but differing as follows.

Type Material
Bolton (2000) - Holotype worker, JAPAN: Mt Futabayama, Hiroshima City, Hiroshima Pref., Honshu, 2.viii.1996 (Y. Touyama) [examined].

Determination Clarifications
The species had not been treated in MSJ (1988) nor Ogata & Onoyama (1992). But later Terayama et al. (1994) nominated the ant from Hiroshima Prefecture in their distribution table as Smithistruma sp. 9 and gave a Japanese name Hiroshima-uroko-ari. The species also corresponds to Smithstruma sp. 3 of Ogata et al. (1994).

References based on Global Ant Biodiversity Informatics

 * Ogata K. and Onoyama K. 1998. A Revision of the Ant Genus Smithistruma Brown of Japan, with Descriptions of Four New Species (Hymenoptera: Formicidae). Entomological Science 1: 277-287