Icriodus riosi, a new conodont species from the Lower Devonian of the Spanish Central Pyrenees

The conodont Icriodus riosi n. sp.from the Lower Devonian of the Spanish Central Pyrenees is described and discussed. It is characterized by a spindle with straight margins and a short outer process that forms an obtuse angle with the main axis of the element and it is probably closely related to the curvicauda-celtibericus group. It ranges from the pireneae Zone (late Pragian), slightly below the kitabicus Zone, to the early part of the nothoperbonus Zone (late early Emsian). The abundance and diversity of the different species of the genus found in the same sections, e.g. Ic. curvicadua, Ic. celtibericus, Ic. bilatericrescens or Ic. gracilis, suggests that during this time interval an evolutionary radiation of the group took place, a phenomenon that until now had only been documented for the genus Polygnathus.