"The Orange-legged Swift spider or Nyssus coloripes is one of the fastest spiders in Australia. While running, it waves its two forelegs above its body, mimicking the two antennas of a wasp.
The front two legs have a brown tinge. Male and females are identical and their length varies between 5 and 7 mm.
This species is closely related to much larger Supunna albopunctum (7 -12 mm) but this spider has two rows of white dashed spots on its abdomen.
In autumn and winter the females construct a flat very white disc shaped egg-sac of 5-6 mm. The spider feeds on ground dwelling insects and spiders."
Lifted from
https://ednieuw.home.xs4all.nl/australian/sacspiders/sacspiders.html