The Les Vilelles unit is a detrital sequence exposes at the southwestern margin of the Catalonian Coastal Range, NE Spain, below the Carboniferous turbiditic series. Based on the palynological content, the age of this unit was initially assigned to the Middle-Late Devonian (Eifelian to Famennian). Additional radiolarian and connodont findings were considered to be Early-Middle Mississippian (Tournaisian to early Viséan). This age inconsistency and the broad time interval, especially of the first dating, produce some ambiguity in the regional interpretations of the Les Vilelles unit and the overlying Carboniferous sequence. A palynostratigraphic analysis conducted in a section representative of the Les Vilelles unit has provided an assemblage containing miospores, acritarchs, prasinophyta phycomata and chitinozoan that can be confidently assigned to a latest Frasnian interval, in contact with the Frasnian-Famennian boundary. This dating casts doubt on the radiolarian/connodont age assignment and considerably refines the Middle -Late Devonian age formerly established. This study also includes a systematic section with the description of three newly established miospore species:Dibolisporites coniugatum, Dibolisporites priorato and Rugospora spinosa.