A redescription of the Stephanian species Callipteridium virginianum (Fontaine & White, 1880) comb. nov. and Alethopteris leonensis Wagner, 1964

An analysis of Alethopteris virginiana Fontaine & White from the lower Dunkard in the Appalachians of North America shows that three different taxa are likely to be represented in the initial illustration. The specific epithet ‘virginiana’ ought to be restricted to a form comparable to Callipteridium costei (Zeiller) Wagner, whereas the two other taxa are referred to pecopterid ferns. A neotype is proposed for Callipteridium virginianum (Fontaine & White) comb. nov. on the basis of topotypes. Zeiller’s illustration of ‘Alethopteris’ costei is reproduced for comparison. On the other hand, a full description and illustration are provided for Alethopteris leonensis Wagner, a species which had been identified previously with Alethopteris virginiana, apparently in error. An associated Holcospermum ‘seed’ is also illustrated. Comparisons include the rather similar Alethopteris bohemica Franke, 1912, which is also illustrated with an associated ‘seed’. The age of the lower Dunkard flora is determined as (early?) Autunian. The relative position of the Upper Pennsylvanian (upper Conemaugh, Monongahela, Dunkard) of eastern North America is depicted in a chart showing the full succession of substages in the West European chronostratigraphic classification of the Pennsylvanian Subsystem, as well as the corresponding megafloral zones.