Hi Alison, I think this one is Anonychomyrma too. In this case the wide, shield-shaped head with a concave curve at the back of the head combined with the black colour and shape of the abdomen is enough to make it unlikely to be Iridomyrmex (though, of course, you could find all these features in Iridomyrmex too, but not quite the same!). Cheers, Jon