The stem of Cortinarius australiensis ( see https://canberra.naturemapr.org/Species/22391) has a membranous ring or skirt similar to the one in your photo but then you'd see a rusty-brown spore deposit on the upper surface of the ring/skirt (which is the remnant of a veil that initially covered the gills, before the mushroom cap expanded). In general, species of Cortinarius have sparse to thick cobwebby veils over the gills, which leave wispy (rather than membranous) remnants once the cap has expanded. If you see a membranous skirt, white gills and those small pyramidal/conical warts on the surface of the cap - go for Amanita. You'll be right almost always.