Strumigenys hiroshimensis

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Strumigenys hiroshimensis
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Strumigenys
Species: S. hiroshimensis
Binomial name
Strumigenys hiroshimensis
(Ogata & Onoyama, 1998)

A rare species found of the forest 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.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Oriental Region: Taiwan.
Palaearctic Region: Japan (type locality).


Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Strumigenys were once thought to be rare. The development and increased use of litter sampling methods has led to the discovery of a tremendous diversity of species. Many species are specialized predators (e.g. see Strumigenys membranifera and Strumigenys louisianae). Collembola (springtails) and other tiny soil arthropods are typically favored prey. Species with long linear mandibles employ trap-jaws to sieze their stalked prey (see Dacetine trap-jaws). Larvae feed directly on insect prey brought to them by workers. Trophallaxis is rarely practiced. Most species live in the soil, leaf litter, decaying wood or opportunistically move into inhabitable cavities on or under the soil. Colonies are small, typically less than 100 individuals but in some species many hundreds. Moist warm habitats and micro-habitats are preferred. A few better known tramp and otherwise widely ranging species tolerate drier conditions. Foraging is often in the leaf litter and humus. Workers of many species rarely venture above ground or into exposed, open areas. Individuals are typically small, slow moving and cryptic in coloration. When disturbed individuals freeze and remain motionless. Males are not known for a large majority of species.

Castes

Nomenclature

The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • 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.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Description

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) (Entomological Laboratory and Institute of Tropical Agriculture, Faculty of Agriculture, Kyushu University) [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