Strumigenys incerta

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Strumigenys incerta
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Strumigenys
Species: S. incerta
Binomial name
Strumigenys incerta
(Brown, 1949)

Strumigenys incerta casent0280713 p 1 high.jpg

Strumigenys incerta casent0280713 d 1 high.jpg

Specimen Labels

Common Name
Language: Japanese

The type-locality of S. incerta is Mt. Kirishima, Kyushu, and the northernmost record of distribution is Matsushima, Miyagi Prefecture (Sonobe, 1977). This species is found on the floor of broadleaf forests, and nests in rotting wood or leaf litter. Collected samples are often accompanied by Cryptopone sauteri, and for this reason Masuko (1985b) has suggested the possibility of social parasitism (xenobiosis) involving these species (Ogata & Onoyama, 1998; Japanese Ant Image Database).


Bolton (2000) - A member of the Strumigenys rostrata-group. Closely related to Strumigenys rostrataeformis and Strumigenys emeswangi of Japan and China. Comparative characters to differentiate these taxa from incerta are given under the former names.


This species is similar to S. rostrataeformis, but can be distinguished by the shape of the anterior margin of its clypeus and the mesosomal hairs (Japanese Ant Image Database).

Keys including this Species


Distribution based on Regional Taxon Lists

Palaearctic Region: China, Japan (type locality), Republic of Korea.

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb


Masuko (1984) observed and reported on what he called "body smearing behavior" in S. membranifera and other Strumigenys species (see Strumigenys behavior).



The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

  • incerta. Smithistruma (Smithistruma) incerta Brown, 1949d: 10 (w.q.) JAPAN. Combination in Pyramica: Bolton, 1999: 1673; in Strumigenys: Baroni Urbani & De Andrade, 2007: 121. Senior synonym of habei: Onoyama, 1980: 194. See also: Bolton, 2000: 459.
  • habei. Smithistruma (Smithistruma) habei Azuma, 1951: 89, figs. A, B (w.) JAPAN. Junior synonym of incerta: Onoyama, 1980: 194.

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

Brown (1949) - I consider that the worker and female now in the Museum of Comparative Zoology, collected by Prof. Silvestri at Kirishima Mountain, Kyushu, and determined by Wheeler as Strumigenys japonica, represent a new species of the rostrata group probably distinct from the types of japonica. I leave it to some worker who has access to the japonica types to give final proof of the identity of japonica. The same female which Wheeler used as a model for his description of the gynetype of the species japonica as that author saw it is here made the holotype of incerta, since the single worker available to me (taken with the female at Kirishima Mt.) has the postpetiole and gaster missing.



Brown (1949) - Ergatotype. The estimated probable TL is in the neighborhood of 2.15 to 2.20 mm., HL 0.56 mm., WL 0.52 mm., CI 66, MI 13.

Head in general shape and proportions like that of Strumigenys rostrata which has been well figured by Emery (1895, Pl. 8, fig. 23) and M. R. Smith (1931, Pl. 2, fig. 8). (These figures, especially that of Smith, will serve to illustrate. the general head shape of the entire rostrata group if allowances are made for variation in mandibular length, pilosity and the degree or absence of emargination of the anterior clypeal border.)

Head strongly convex across the vertico-occiput in both directions: frontal area subtriangular, rather small, sharply depressed below the level of the posterior clypeal border, to which it is connected by some short, very indistinct longitudinal striae. Posterior border broadly but rather shallowly excised, excision perhaps a little less deep than in rostrata. Clypeus about 1.10 times broader than long, surface of disc weakly convex behind and with a low tumulus just anterior to its center, center of anterior clypeal border slightly depressed and slightly but dis· tinctly emarginate, the emargination in both ergatotype and holotype female more marked than in specimens of rostrata showing somewhat similar emargination.

Mandibles like those of rostrata, but decidedly shorter (MI in both holotype and ergatotype 13; MI in rostrata 19-21). The dentition is apparently similar to that of rostrata in that the basal mandibular tooth is not separated from the apical series of teeth by a diastema ; though the mandibles were not opened in either specimen, the basal tooth seems, from what can be seen of it, to be acute like that of rostrata and an undescribed species from California in my working collection. The blades are rather broad across their bases and moderately depressed.

Antennal scape L 0.28 .mm.; slightly bent near base, flattened and slightly incrassate, the ·anterior border obtusely angulate at the bend. Funiculus L 0.41 mm.; apical segment (V) between 1} and 1l times the length of segments I through IV of the funiculus taken together. Eyes much as in the worker of rostrata.

Alitrunk like that of rostrata, but no so strongly depressed anteriorly. In lateral profile, the anterior slope of the pronotum gently convex, forming nearly a 45° angle with the posterior dorsum, but meeting the latter through the rounded promesonotal convexity. The posterior part of the mesonotum and the dorsum of the propodeum forming a nearly straight dorsal outline; the postmesonotal suture scarcely noticeable in lateral view, but visible as a dark transverse line seen from above. Pronotum arcuately rounded and marginate anteriorly; humeri rounded, each with an indistinct piligerous tubercle. Median longitudinal carina extending length of promesonotum, but very weak. Propodeal lamellae as in rostrata, each forming a small acute tooth above, narrow and concave beneath this, not widened ventrally, but forming a small angle at its ventral terminus.

Petiole pedunculate, with spongiform tissue forming fair-sized flaps on each side of the dorsally rounded node and a heavy ventral longitudinal band beneath.

Head obscurely tuberculate above posteriorly. Head, alitrunk (except posterior pleurae, which are partly smooth and shining) and petiole densely reticulate-punctulate and opaque. Postpetiolar node and gaster (as shown by the female) smooth and shining, the latter with a few long, weak costulae extending about the basal quarter of the length of the first gastric tergite. Clypeus, except for the feebly shining tumulus, punctulate-granulate and opaque.

Clypeus with very small separated suberect to subreclinate spatulate hairs on the disc, the lateral borders of the free margin of the clypeus on each side with about 6 longer, medially curved spatulate hairs, which are nearly even in length and not very broad (each hair broader than the corresponding one of rostrata and the fringe more even; hairs not so broad as in Strumigenys creightoni M. R. Smith (1931, Plate IV, fig. 16). The emarginate portion of the anterior clypeal border with three or four small hairs on each side of the middle, these very indistinct and becoming shorter nearest the midline. Dorsum of head posterior to clypeus with short, erect clavate hairs which become progressively longer posteriorly, those on the extreme occiput longest and scarcely thickened at the tips. Antennal scapes each with about 9 more or less perpendicular straight or nearly straight prominent hairs which are weakly broadened at the tips; the longest, at the angle near the base of the anterior border, is about as long as the greatest width of the scape. Dorsum of alitrunk with a sparse growth of hairs like those on the occiput; erect and weakly or not at all enlarged apically. Hairs on petiole, postpetiole and gaster (in both female and worker) similar to those of occiput and alitrunk, those on the gaster longest, weakest and least or not at all apically enlarged, moderately abundant above, more abundant and shorter below. Humeral tubercles each bearing a long, weak crooked flagellate hair.

Color ferrugineous yellow.


Brown (1949) - Holotype. Differing from worker in the usual characters of full sexuality (ocelli, thoracic and gastric regions more strongly developed, compound eyes larger, etc.), the compound eyes relatively larger and more prominent than in the female of rostrata. Dorsum of mesonotum not clearly striate or rugulose, but the punctulae forming indistinct longitudinal rows. Ocellar triangle darkened. Postpetiole with abundant spongiform appendages, which are probably much the same in the worker caste. TL 2.36 mm., HL 0,59 mm., WL 0.62 mm., CI 70, MI 13, Clypeus L1 times as broad as long.

Type Material

Bolton (2000) - Holotype queen and paratype worker, JAPAN: Kyushu, Kirishima Mountain (Silvestri) (Museum of Comparative Zoology) [examined].


References based on Global Ant Biodiversity Informatics

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