Petroxestes altera, a new bioerosional trace fossil from the upper Maastrichtian (Cretaceous) of northeast Belgium

A new ichnospecies, Petroxestes altera, is erected for a distinctive boring (ethological class: domichnia) in the hemipneustid (holasteroid) echinoid, Hemipneustes striatoradiatus (LESKE, 1778), from the lower Nekum Member (Maastricht Formation, late Maastrichtian) at Eben Emael, province of Liège (northeast Belgium). Hitherto, the type ichnospecies of Petroxestes, P. pera WILSON & PALMER, 1988, has been recorded from the Ordovician-Lower Silurian of the United States and Canada and from the middle Miocene of Carriacou (The Grenadines). In overall morphology, the new taxon closely resembles the type ichnospecies, but differs in displaying slightly chipped margins and a well-developed sculpture of undulating grooves, of variable depth and width, on the bottom of the trace, overprinted by small scratches which do not show any preferred orientation. The producer most likely was a sipunculan worm.