Aphaenogaster irrigua

This species prefers moist situations; it nests in the soil in woodlands, near banks of streams and dry river beds. Foraging workers do not turn their gasters downwards (Japanese Ant Image Database).

Identification
Total length of workers around 4 - 6 mm. Head brown to light brown, mesosoma light brown, gaster dark brown to brown, legs light brown. Scapes, mesosoma and legs relatively rather long compared to other Japanese Aphaenogaster species. Anterior portion of clypeus with transverse striae. Basal margin of mandibles often weakly serrate. Mesonotum only weakly raised, predominantly covered with punctures. Similar to Aphaenogaster osimenseis, but separable by the presence of shallow, small punctures on the occiput and pronotal dorsum, and the dull surfaces of the propodeum and lateral parts of mesopleura, which are covered with striae and punctures. (Japanese Ant Image Database)

Distribution based on Regional Taxon Lists
Palaearctic Region: Japan.

Biology
Chromosome number 2n=32.

Nomenclature

 * . Aphaenogaster irrigua Watanabe & Yamane, 1999: 734, fig. 18 (w.) JAPAN.
 * Status as species: Imai, et al. 2003: 178.

References based on Global Ant Biodiversity Informatics

 * Shimono A., and S. Yamane. 2003. Ant species diversity on Okinoerabu-jima, the Ryukyus, southern Japan. For the Establishment of Remote Islands Study (Kagoshima Univ.) 3: 11-29.
 * Terayama M., S. Kubota, and K. Eguchi. 2014. Encyclopedia of Japanese ants. Asakura Shoten: Tokyo, 278 pp.
 * Watanabe H., and S. Yamane. 1999. New species and new status in the genus Aphaenogaster (Formicidae) from Japan. Pp. 728-736 in: Yamane, S.; Ikudome, S.; Terayama, M. 1999. Identification guide to the Aculeata of the Nansei Islands, Japan. Sapporo: Hokkaido University Press, xii + 831 pp.
 * Yamane S. 2016. How many species of Ants in Amami Islands? (in Japanese). Part 2, chapter 1 in How many species of Ants in Amami Islands? Pp. 92-132.
 * Yamane S., S. Ikudome, and M. Terayama. 1999. Identification guide to the Aculeata of the Nansei Islands, Japan. Sapporo: Hokkaido University Press, xii + 831 pp. pp, 138-317.
 * Yamane S., Y. Harada, and K. Eguchi. 2013. Classification and ecology of ants. Natural history of ants in Southern Kyushu. 200 pages
 * Yamane S.; Ikudome, S.; Terayama, M. 1999. Identification guide to the Aculeata of the Nansei Islands, Japan. Sapporo: Hokkaido University Press, xii + 831 pp. pp138-317.