Danziella artesiana, a new name for Zosterophyllum artesianum from the Lower Devonian of Artois, northern France

Abstract

A reinvestigation of the Lower Devonian plant, Zosterophyllum artesianum Danzé-Corsin 1956, based on original collections and undescribed material leads to the erection of a new taxon, Danziella artesiana. The genus shares with Zosterophyllum smooth axes with lateral stalked sporangia comprising two equal valves, but in the French plant the stalks, attached at right angles to the fertile axes, are long and straight. Distal dehiscence occurs in the same plane of compression as the subtending axis. Sporangia are attached at irregular intervals and there is no well-defined spike. Anatomical evidence that would confirm affinity with the Zosterophyllales is lacking in these compression fossils. Consideration is also given to its relationship to taxa such as Renalia Gensel that appear to share characters with zosterophylls and rhyniophytes, with consensus that a basal position in the former seems more likely. However the age of the fossils, (Pragian–Emsian), based indirectly on spores, fish and field relationships, postdates that of the major radiation of zosterophylls elsewhere on the Old Red Sandstone Continent.