New cheirurid trilobites from the Lower Ordovician Fezouata Biota, Radiantospina gen. nov. (Pilekiinae) and Foulonia (Eccoptochilinae)

 

Authors: Pérez-Peris F, Losso SR, Richards JC, Nanglu K, Álvaro JJ, Vidal M, Ortega-Hernández J

Published in: Bulletin of Geosciences, volume 101, issue 1; pages: 65 - 81; Received 22 November 2025; Accepted in revised form 28 February 2026; Online 3 May 2026

Keywords: Trilobita, Cheirurina, Tremadocian, Floian, Fezouata Shale, Morocco,

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Abstract

We describe the pilekiine trilobite genus (Family Cheiruridae) Radiantospina gen. nov. (type species R. helioaspis sp. nov.) from the Lower Ordovician (upper Tremadocian, Sagenograptus murrayi graptolite Zone) Fezouata Shale in Morocco. Radiantospina is characterized by a distinctive thoracic morphology in which the proximal part of the thoracic pleura bears a transverse pleural furrow that extends two-thirds of the total width of the pleural band. Radiantospina resembles the poorly known genus Courtessolium from the Tremadocian (Euloma filacovi Zone) of the southern Montagne Noire, France, but differ in terms of the thoracic pleural furrow morphology and the shape and arrangement of the pleural spines. We also revise the species Foulonia peregrina, the type species of the genus. Foulonia is the stratigraphically oldest genus assigned to the cheirurid subfamily Eccoptochilinae. New material from the Floian levels (?Baltograptus jacksoni graptolite Zone) of the Fezouata Shale shows the occurrence of the genus along the northwestern perigondwanan margin linking Montagne Noire (South France) and Morocco (NW Africa).