Caulostrepsis avipes Bromley et D’Alessandro, 1983

Emended diagnosis.—Caulostrepsis with or without a vane, dumbbell-shaped to flattened oval in cross section, characterized by the possession of two to four grooves branched out from the aperture. The grooves are shorter than the triple width of the boring. In some cases, the branching occurs beneath the substrate surface, so that each diverging branch bears its own aperture.

Remarks.—Most probably, the surface depressions resulted from erosion/collapse of the roof of subsurface galleries. The roof is still present in the distal part of some galleries. Information that the grooves branching out from the apertures are much shorter than the remaining part of the boring is added to the diagnosis by Bromley and D’Alessandro (1983) in order to describe the distinction between Caulostrepsis avipes and the new ichnospecies described in the following. The grooves were probably produced by the tentacles of spionid polychaetes. It is the first appearance of this ichnospecies beyond the Upper Cretaceous, where it is documented by Reis (1921) but without assignation to any ichnotaxon, and by Hillmer and Schulz (1973) under Ramosulcichnus biforans Gripp, 1967, which was transferred to Caulostrepsis and split into Caulostrepsis as C. biforans and C. avipes (see Bromley and D’Alessandro 1983).

Diagnosis. Caulostrepsis with or without a vane, dumbell-shaped to flattened-oval in cross section, characterized by the possession of two to four grooves branched out from the aperture. In some cases the branching occurs beneath th substrate surface co that each diverging branch bears its own aperture.