The Tumbesian tyrannulet was formerly considered conspecific with the widespread southern mouse-colored tyrannulet. The two species are visually very similar, but vocally distinct.[3]
References
^"Tyrannidae". aviansystematics.org. The Trust for Avian Systematics. Retrieved 2023-07-16.
^Gill, Frank; Donsker, David, eds. (2019). "Tyrant flycatchers". World Bird List Version 9.2. International Ornithologists' Union. Retrieved 27 June 2019.
^Rheindt, Frank E.; Norman, Janette A.; Christidis, Les (2008). "Genetic differentiation across the Andes in two pan-Neotropical tyrant-flycatcher species". Emu. 108 (3): 261–268. Bibcode:2008EmuAO.108..261R. doi:10.1071/mu08020. S2CID83868957.