Nuskoisporites dulhuntyi from the Cisuralian and Lopingian of the Southern Alps: A morphological comparison between dispersed and in situ prepollen

Abstract

Nuskoisporites dulhuntyi is considered one of the biostratigraphic marker species for the Lopingian of Europe. A morphological comparison between Kungurian (Cisuralian) and Wuchiapingian (Lopingian) Nuskoisporites dulhuntyi prepollen (dispersed from five outcrops and in situ from one cone) from the Southern Alps has been carried out. Dispersed Nuskoisporites dulhuntyi prepollen grains from the Kungurian (Cisuralian) of the Athesian Volcanic District (AVD) and the Wuchiapingian (Lopingian) of Bletterbach have been compared with the in situ prepollen grains isolated from an Ortiseia cone of the Bletterbach outcrop. Using light microscopy, we measured overall size, central body size, and laesurae length of the prepollen grains revealing significant overlaps in morphological characteristics between the different assemblages. The main difference is the bigger size of the in situ pollen grains in comparison with the dispersed ones, but a significant overlap is still observed. This implies that the prepollen grains from the Kungurian sedimentary successions of the Athesian Volcanic District can be assigned confidentially to the dispersed prepollen species Nuskoisporites dulhuntyi and hence, represent the so far oldest record of this taxon, extending the species range from the Guadalupian back to the late Cisuralian.