Zephyrarchaea austini

The Kangaroo Island assassin spider is 2 mm (0.079 in) in size and lives in leaf litter of wet eucalypt woodland near Billy Goat Falls[4] in the Western River Wilderness Protection Area on the island.

The females are distinguished from other members of the Zephyrarchaea genus by a small body size, a carapace length of less than 1.10mm a height/length ratio of less than 1.70mm. Additionally they have no tubercles on the abdomen, and a "strongly concave post-ocular depression in the lateral view". The males are unknown.[2]

They were thought to be possibly extinct following the 2019–2020 Australian bushfires, after their only known habitat was burnt.[4] The scientists who originally discovered it describe its survival is "unlikely at best".[3]

However, a female and a juvenile spider were found in September 2021 by researchers from the South Australian Museum, and DNA analysis confirmed that they were of the same species. The facts that they were found outside the species' formerly known range in the Western River Protection Area, and that one is a juvenile, has given hope that there may be more populations. However the low dispersal remaining after the fires has likely led to less genetic diversity and therefore greater vulnerability, so intervention may be considered in the future to assist survival.[5]