Underground passage system of Macrotermes carbonarius (Isoptera, Termitidae) in a dry evergreen forest of northeast Thailand

The complete underground passage systems of six colonies of the termite Macrotermes carbonarius in a dry evergreen forest within the Sakaerat Environmental Research Station, northeast Thailand, were excavated. We found 4-10 main underground passages radiating out from each mound, with smoothly plastered floors (6-35 cm below the soil surface). All of the underground passages were well built (2.5-13 cm wide) and one of the main passages extended 33 m from the nest. The total length of the passages of each colony varied between 33.8 m and 112.8 m. It was demonstrated that 5 adjacent colonies of M. carbonarius generally segregated their underground passages horizontally. Vertical segregation of the passages of M. carbonarius from a subterranean nest of the neighboring species, Macrotermes annandalei was also found. In contrast to other Macrotermes species, the underground passage system of M. carbonarius only consists of major tracks and lacks a dense network of passages in the terminal part of the system. In the vicinity of their foraging sites, M. carbonarius forages in the open using pavement trackways on the ground, which are considered to be equivalent to a dense network of fine passages of other Macrotermes species.