Hey Nnnnsic,
Wow, two ant pix in the one day - I'm in heaven

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This ant is Myrmecia brevinoda and I believe Rel recently had quite a close encounter with one! These guys are big and aggressive and have a nasty sting. If you think the jaws look big, that's not the end you should be worried about - the jaws are just used to hold on while they stab you with their long sting. Very painful (I know from experience).