Reiser's Tyrannulet is recorded in Brazil and Paraguay. It has bright yellow-green upperparts and pale yellow underparts, and the field account reports it most often in gallery forest in Brazil's Cerrado.
The upperparts are bright yellow-green and the underparts pale yellow, with only a faint olive wash across the breast. The crown feather tips are grey, and the lores and cheeks yellowish-white.
In Brazil's Cerrado it was reported most often in gallery forest, where it perches low above the ground.
An extinction-risk assessment has not been added yet.