The Spot-breasted Thornbird occurs only in northwest Argentina and adjacent Bolivia. It has at times been treated as a subspecies of the Freckle-breasted Thornbird (Phacellodomus striaticollis) which is understandable as the two look quite a bit alike. However, their distributions are separated by the Chaco and Monte Desert; with Spot-breasted Thornbirds being found west of there in moist Yungas forest edge. The Spot-breasted is darker than the Freckle-breasted, is more extensively rufous on the face. In particular note that the pale spots on the breast stand out more on the Spot-breasted Thornbird. The song of the Spot-breasted is faster than that of its eastern relative. The lush, moist forested habitat that this thornbird takes is distinctive in this group of dry forest specialists.