Trypanites fimbriatus (Stephenson, 1952)

Diagnosis– Single, slightly club-shaped borings having the distal portion a little swollen; axes are straight or gently curved, generally perpendicular to the surface from which the borings originate, but in thin substrates they are forced to run parallel to it. They neither cross each other nor interpenetrate, but show avoidance growth strategies.

Description– Single, slightly curved, club-shaped, unbranched borings each parallel to the substrate surfaces. Lengths average 2·5 mm. The distal portions are swollen and taper to form semicircular terminations. The thicknesses of the borings are consistent and average 520 μm proximally; the diameter of each neck is abruptly reduced to an average diameter of 200 μm.