A revision of Reduviasporonites Wilson 1962 : description, illustration, comparison and biological affinities

Optical and electron microscopy of topotype material confirms that Reduviasporonites Wilson 1962 is the senior synonym of Chordecystia Foster 1979, and Tympanicysta Balme 1980. Moreover the type species of the last two genera, assigned in 1999 to Reduviasporonites by Elsik as R. chalastus (Foster) and R. stochianus (Balme), are conspecific. The type species, R. catenulatus Wilson 1962, differs from R. chalastus in that its constituent cells are significantly
smaller, more rounded, and have less well developed connecting areas (terminal rims) between cells. Brazilea helbyi forma gregata Foster 1979, recorded only from the type material of R. chalastus, is likely to be a junior synonym of that taxon.
The stratigraphical occurences of the species of Reduviasporonites suggest that R. catenulatus is most common in the Wordian (Kazanian) of Oklahoma, though specimens of the size range associated with R. catenulatus are present very rarely in the Early Triassic Mazzin Member of the Werfen Formation, Austria. R. chalastus is present in Changhsingian to Griesbachian rocks spanning several million years and is therefore present outside narrow sequences spanning the Permian-Triassic boundary. The size of the constituent cells present in R. chalastus appears to be related to palaeolatitude with large examples occurring in the palaeotemperate Permian of China, Russia, and Australia (Moura) and smaller specimens occurring in the palaeotropical and paleoequatorial Permian of northern Australia, Saudi Arabia, UK and Austria.
Geochemical analysis of R. chalastus from the Mazzin Member (Lower Triassic, Austria) suggests that it may be of algal rather than fungal origin. This implies that R. chalastus is unlikely to be integral to the process of mass extinction occurring at or near the Permian-Triassic boundary, as suggested by Visscher and other workers, because it appears to range outside the postulated time of mass extinction, and because as a probable alga rather than a fungus, it cannot have acted as a saprophytic metaboliser of dead vegetation formed in the extinction event.