Asteropyginae Trilobites from the Devonian of the Ougarta (Algeria)

In the Ougarta (S-W Algeria), the Lower Devonian Asteropyginae trilobites are represented by nine genera, two of which are new (Hollardops n. g. and Destombesina n. g.), and eleven species, five of which are new: Treveropyge djemelensis n. sp., Treveropyge saourensis n. sp., Hollardops lemaitreae n. sp., Destombesina ougartensis n. sp. and Kayserops djazaïrensis n. sp. These species are irregularly distributed in the six studied sections from the Lochkovian to the Upper Emsian. For the first time, a paedomorphic ontogeny is proved in the Asteropyginae, marqued by the development of only 10 thoracic segments by Hollardops n. g. The pygidium of Destombesina n. g. have only 4 pairs of lateral spines resulting from progenesis. This trilobites fauna shows affinities with the Asteropyginae from Moroco and from the ibero-armorican Domain. The Ougarta is characterized by the absence or the rarity of the Asteropyginae during the Pragian and the Lower Emsian whereas, in the two aforesaid regions, this period correspond to an important development of the sub-family. The disappearance of the Asteropyginae at the Emsian/Eifelian boundary in the Ougarta contrasts with its development in Europe at the same time.