A different Meranoplus, larger and hairier than the all-red ones usually seen. They appeared to be excavating a nest and were very well camouflaged by the dirt sticking to them. The abundance is only a guess - there was much movement in and out of the hole as they deposited their loads. (I have only ever seen the red ones singly, and never at a hole.)
Great photos Cath, and great to see the nest entrance. There is at least two species at Mulligans Flat / Goorooyaroo, but there may be more. Cheers, Jon