A new species of the iconic triradial Ediacaran genus Tribrachidium, from Nilpena Ediacara National Park, Flinders Ranges (South Australia)

Tribrachidium heraldicum is a tri-radial Ediacaran organism found in abundance within the Ediacara Member of the Flinders Ranges, South Australia. Here we report and describe a new species within the genus Tribrachidium: Tribrachidium gehlingi sp. nov. from Nilpena Ediacara National Park (NENP), South Australia. T. gehlingi sp. nov. has low relief and three slightly curved main arm-like structures that leave a conspicuous gap between the end of the arm-like structures and rim. In place of the ‘bulla’ found on T. herladicum, there are three secondary arm-like structures approximately half the length of the main arm-like structures. We find that key morphological differences between the species are statistically significantly different from T. heraldicum. Additionally, both species occur together within the same fossiliferous event horizons, indicating that the observed morphological differences are unlikely to be a result of taphonomy.