New termite trace fossils: Galleries, nests and fungus combs from the Chad basin of Africa (Upper Miocene–Lower Pliocene)

Abstract

Four new trace fossils of termites are described from the Upper Miocene and Lower Pliocene continental sandstones of the northern Chad basin. Coatonichnus globosus, ichnogenus and ichnospecies nov. is a large ellipsoidal termite calie (20–40 cm in diameter) more or less flattened at both poles. It is morphologically very similar to the nest of extant termite Hodotermes mossambicus from South Africa. It exhibits an internal shelved pattern of modern Hodotermitidae such as the superposition of flat chambers separated vertically by ramps, columns, walls, and pillars. It is interpreted as the nest of an ancestral species of Hodotermes (Hodotermitidae). The new ichnospecies Vondrichnus planoglobus is composed of dense swarms of tens of chambers connected by a net of straight galleries developed in a single plane. The chambers (5–12 cm in diameter) have a spherical shape with a planar base. Generally, short galleries connect each chamber to the straight main tunnel of meter to decameter-scale length. Vondrichnus planoglobus is interpreted as polychambered diffuse nests of fungus-growing termites (Macrotermitinae, Termitidae). Microfavichnus alveolatus, ichnogenus and ichnospecies nov. is a small-scale alveolar mass (3–8 cm by 2–4 cm). The base of the construction is flat to concave. It is entirely composed of a sub-horizontally layered, alveolar-like structure composed of a regular juxtaposition of millimetre-scale round pellets or balls (mylospheres). Microfavichnus alveolatus is interpreted as fossilized fungus combs of “fungus-growing” termites (Macrotermitinae, Termitidae). Termitichnus schneideri, ichnospecies nov. is a large-scale extremely flattened construction (15–60 cm in diameter and 6–18 cm in height). The internal shelved pattern is composed of flat chambers separated by columns, walls, and pillars. Each level is connected by ramps. An external wall surrounds the framework constructed. One to several peripheral funnel-shaped tunnels occur sub-perpendicular to the construction. This new Termitichnus ichnospecie s is interpreted as being a possible central hive of the Vondrichnus planoglobus net.