Architecture and morphogenesis in the mound of Macrotermes michaelseni (Sjöstedt) (Isoptera: Termitidae, Macrotermitinae) in northern Namibia

The mounds of Macrotermes michaelseni (Sjöstedt) in northern Namibia have a characteristic architecture, being divided into three structurally distinct components: a central cone-shaped mound, topped by a tall, thin spire which tilts northward at an angle similar to the sun's average zenith angle, and a broad outwash pediment that results from erosion off the mound. Internally, the mound is permeated by a complex network of tunnels that can be divided into three broad types: a capacious central chimney that extends upward through the center of the mound from the colony up to the apex of the spire; a vertically-biased network of surface conduits that lies roughly one to two cm below the surface, and an interweaving network of lateral tunnels that connect the chimney and surface conduits. A model of mound morphogenesis is proposed which accounts for most of these structural features, and which points toward a general model for the relationship between mound architecture and social homeostasis among the macrotermitine termites.