[2][7] Its exact relationship to other members of genus Synallaxis is uncertain but it is believed to be closest to the dark-breasted spinetail (S.

Their crown is orange-rufous, their nape smoke-gray, and their back, rump and uppertail coverts light grayish brown.

Their iris is light grayish to pale brownish yellow, their bill horn-gray with a paler outer half to the mandible, and their legs and feet horn gray.

It is believed to feed on arthropods by gleaning from vegetation small branches like other members of genus Synallaxis.

[9] As of late 2023 xeno-canto had no recordings of Rio Orinoco spinetail vocalizations and the Cornell Lab of Ornithology's Macaulay Library had only a few.

The species' main vocalization is "a series of 6–9 rapid but well-separated notes, first one accentuated [and that are] not run together in a rattle-trill".