The compound synangial organ Potoniea krisiae sp. nov. and its plausible relationship with linopterids based on cuticles from the Late Pennsylvanian Sydney Coalfield, Canada

Abstract

Abstract Seven compression fossils of the compound synangial organ Potoniea sensu stricto are reported for the first time from Cantabrian-aged (late Moscovian) strata in the Sydney Coalfield, Nova Scotia, Canada. They occurred at a single locality, mostly in the proximo-distal repose position clearly showing sporangia overextending the distal-proximal surfaces, and with one specimen laterally compressed. Specimens were studied under SEM and sporangia were macerated to reveal in situ microspores. The organs are characterized as a compound synangial organs consisting a very narrow stalk, vascularized proximal cap and an outer cover of sporangial parts. Long, cylindrical sporangia are grouped with synangia, terminating as free sporangial tips that extend from the distal surface of the compound synangial organ. Sporangia are densely filled with trilete, verrucate to rugulate microspores of the Verrucosisporites type. Taxonomically significant is the potential of using the cuticles from the cap of the compound synangial organ that have continuously thick bifurcating veins and stomata to link with the associated linopterid foliar taxa Linopteris and Alethopteris occurring within the Sydney Coalfield. Problems are encountered from the non-availability of linopterid cuticles and the poor preservation of Potoniea cuticles. Considering the newly discovered features, the new species Potoniea krisiae sp. nov. is proposed.