A typical member of its genus of Spinetails, the Spix's Spinetail (also known as the Chicli Spinetail) has a dark throat patch and a contrasting rufous crown and wings. The tail structure is also typical of the genus, being long and steeply graduated, with sharply pointed individual feathers, the central pair thinning towards the tip. The nest is cylinderacil in shape, with a long lateral entrance tube. It is made from thorny sticks, has a dense roof to provide protection from rain, and is lined with leaves, moss and hair.