Diagnosis: Deeply penetrating whip-shaped microboring with a basal swelling tapering towards a long, thin, filamentous tube extending straight into the substrate.

Description: The traces are usually found collapsed to the castsurfaceandonlypartiallyetchedsamplesrevealtheirdeeply penetrating nature (Fig. 2D). The traces occur clustered in large numbers of up to several hundred individuals (Fig. 2B, H; 5A–B). The circular, basal swelling of the individual traces is up to 20μm wide and the whip-shaped tunnel is tapering, towards a thin (1–2μm) filamentous gallery extending straight and deep (up to several 100μm) into the substrate. Differential etching of non-homogeneous substrate may be expressed by a corrugated micro-sculpture (Fig. 2C, F). Bifurcations are rare but may be present at the distal end of the basal swelling (Fig. 2E). In initial stages of the boring, the swelling is minute or absent (Fig. 2G)