Tetramorium tsushimae

The Japanese pavement ant, T. tsushimae is one of the most commonly encountered ants in southern Japan.

Identification Keys including this Taxon
Key to US Tetramorium species

Distribution based on Regional Taxon Lists
Nearctic Region: United States. Palaearctic Region: China, Democratic Peoples Republic of Korea, Japan, Mongolia, Republic of Korea, Russian Federation.

Biology


This is Tetramorium tsushimae, Japanese pavement ant, feeding on mooshy cracker fragment, in a play area, in a suburb of St. Louis, Missouri. Light colored individuals among the dark ones are typical of this species, which is a bit smaller than Tetramorium immigrans, (2.5-2.8 mm vs. 2.9-3.2 mm). Colonies are polygyne, polycalic. The species is native to Japan, the Korean Peninsula, and temperate China. USA population originated in Tokyo area, so says its DNA (James Trager).

Sakata et al. (2017) examined how this ant uses cuticular hydrocarbons (CHCs) in recognizing aphid mutualists. Workers of the ants were obtained from a colony found on the campus of Chiba University in Matsudo, Japan. This colony had ~1,000 workers and 3 queens. Tetramorium tsushimae tends the aphid species Aphis craccivora in Japan, and it has been shown there is a correlation in decreasing aggressiveness of the ants towards the aphids with increasing familiarity, i.e., via interactions when collecting honeydew (Hayashi et al. 2015). Another aphid species, Acyrthosiphon pisum, that are also in the ant's environment are never tended. Using a combination of extracted aphid CHCs and synthetic standards, worker reactions towards whole aphid CHCs, methylalkane fractions, and n-alkanes were tested. The ants were less aggressive toward the CHC profile of A. craccivora and methylalkane fractions from this aphid. The ants reacted negatively toward CHC profiles from A. pisum and n-alkane. This suggests T. tsushimae is learning and recognizing aphid mutualists using CHCs and, in particular, methylalkanes.

Nomenclature

 *  tsushimae. Tetramorium caespitum subsp. tsushimae Emery, 1925c: 187, fig. C (w.q.) JAPAN. Synonym of jacoti: Wheeler, W.M. 1927d: 7. [Wheeler gives jacoti as senior synonym, but tsushimae has priority and is the first available name for this taxon: Bolton, 1995b: 415.] Raised to species: Bolton, 1995b: 415. [For current synonymy of tsushimae see under its junior synonym jacoti.]
 * jacoti. Tetramorium caespitum subsp. jacoti Wheeler, W.M. 1927d: 7 (w.) CHINA. [First available use of Tetramorium caespitum subsp. semilaeve var. jacoti Wheeler, W.M. 1923b: 3; unavailable name.] Synonym of tsushimae: Wheeler, W.M. 1927d: 7. [Wheeler gives jacoti as senior synonym but tsushimae has priority and is first available name for this taxon: Bolton, 1995b: 415.] Raised to species: Pisarski, 1969b: 303; Radchenko, 1992b: 51. Senior synonym of tsushimae and material of the unavailable names chinensis, geei referred here: Radchenko, 1992b: 51.