Lugardonia paradoxa gen. et sp. nov., a new strobilus from the Anisian flora of Kühwiesenkopf, the Dolomites, Italy and its affinities with emphasis on spore ultrastructure

Abstract

Lugardonia paradoxa gen. et sp. nov., a new strobilus with in situ spores from the Anisian flora of Kühwiesenkopf, the Dolomites, Italy, is described. These strobili show the general gross morphology of a gymnosperm (e.g. a seed fern) inflorescence with male organs consisting of pollen sacs on short stalks. However, they yield large trilete spores (c. 100 µm in diameter), almost circular in equatorial outline, with a smooth inner layer and a granulate–verrucate outer layer (similar to exospore and perispore in fern spores). These spores suggest a pteridophyte rather than a gymnosperm affinity. Because of either macromorphological characters or spore morphology (based on light microscope (LM), scanning electron microscope (SEM) and transmission electron microscope (TEM) analysis, most plant groups are ruled out as possible parent plants for these strobili. Only the ferns and seed ferns might be considered as potential parent plants. The possible affinities of these strobili within the ferns and seedferns are discussed in detail, with special emphasis on the ultrastructural features of the in situ spores. However, no definite conclusions can be drawn, although a fern affinity appears to be the more likely one based on spore morphology.