Pheidologeton diversus

Japanese Name

Yokozuna-ari

Jerdon, T.C. (1851) A catalogue of the species of ants found in southern India. Madras Journal of Literature and Science 17: 103-127.

Ocodoma diversa Jerdon (Jerdon, 1851) , Pheidologeton diversus (Jerdon) (Roger, 1863) ,

Total length between 1.3 and 2.5 mm in minor workers. Body color yellowish brown to reddish brown in minor workers: reddish brown to blackish brown in majors. In minor workers: head rectangular with weakly convex posterior margin in full face view; mandibles each with 5 teeth; antennal scapes short, not exceeding posterior margin of head; each of the apical two funicular segments long, their combined length longer than the rest of funiculus; promesonotum relatively strongly convex in profile; metanotal groove deeply incised; dorsum of propodeum convex; propodeal spines long, with acute apices. In major workers: head proportionately large, almost square, with convex posterior margin in frontal view; anterior margin of clypeus straight, with a shallow median notch; mandibles large, triangular, with an acute apical tooth; masticatory margins without distinct teeth; eyes relatively small; ocelli present; antennal scapes 0.5 times as long as head; subpetiolar process present.

There are many intermediate forms between the smallest minor and largest major workers in Pheidologeton. They show continuous allometric variation in size and morphology. The head of the largest major worker may be around 10 times as large as that of a small minor, and the dry weight of a large major can be around 500 times that of a small minor (Moffett, 1987). Division of labor is correlated with these size-related morphological differences, and with the age of individual workers; for example, younger minor workers specialize in carrying for the larvae, but extend their activities as they grow older (Moffett, 1987). P. diversus forms large colonies, often found in the soil or under stones. It regularly forms long foraging columns. Arcades constructed of soil particles sometimes roof the trails. P. diversus is a predator of small animals such as insects (Moffett, 1986). It also collects nectivorous materials. This species is widely distributed from India through SE Asia to Taiwan. There are only two Japanese field records respectively from the Nansei Islands (Okinawa Island) and the Ogasawara Islands (Chicchi-jima Island). Specimens taken at the U.S. Air force base at Zama City, Kanagawa Prefecture, must have originated from a commercial introduction from SE Asia (Kubota, 1988).

Nansei Is (Okinawa I.), Ogasawara Is(Chichi-jima I.) ; tropical and subtropical Asia.