I've hit the books, been studying hard and this is what i've come up with:
T. pinguicolla has been recorded 50km north-east of Armidale and T. diemensis about 75-100km south of Armidale. So could be either but leaning towards T. pinguicolla presuming my geography is correct (Coonamble is east of Armidale isn't it?).
The distinguishing feature appears to be the typmanum. In diemensis it is distinct whereas in pinguicolla it is not. Judging by the pic it would appear as though the tympanic region is covered by scaly skin, therefore i would have to agree with hornet and Jason - T. pinguicolla.