Rufous Grasswren Amytornis whitei is the most widely distributed of three species formerly included within the Striated Grasswren A. striatus complex. Included among four phenotypically, geographically and ecologically distinct populations are A. w. whitei of the Pilbara ironstone ranges of Western Australia and A. w. oweni of inland sandy deserts. The other two are the little-known small-billed isolate of the limestone plateau of the Cape Range, North West Cape Peninsula, Western Australia, and a larger form present in the mallee of the Eyre Peninsula, South Australia. We present morphometric and other data and describe these two populations as new subspecies; both are of conservation concern.