Y−shaped trace fossil (U−shaped upper part with a basal shaft), Parmaichnus stironensis igen. nov. et isp. nov. penetrates from a discontinuity surface cut in Early Quaternary mudstones in the Stirone Valley, Northern Italy. It is attributed to upogebiid decapod crustaceans. Parmaichnus differs from Psilonichnus by the presence of turning chambers in the upper part of the burrow. The turning chambers are considered to be an important taxonomic feature of upogebiid burrows. P. stironensis occurs together with Thalassinoides cf. paradoxicus (produced probably by callianassid crustaceans) and wide U−shaped pyritised cylinders (supposedly produced by balanoglossid hemichordates).