Cnemarchus

Cnemarchus is a genus of South American birds in the tyrant flycatcher family Tyrannidae.

Cnemarchus
Red-rumped bush tyrant (Cnemarchus erythropygius)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Passeriformes
Family:	Tyrannidae
Genus:	Cnemarchus Ridgway, 1905
Type species
Taenioptera erythropygia red-rumped bush tyrant Sclater, 1853

The two member of this genus are elongated, upright-perching flycatchers that share similar tail patterns. They are found at high-altitudes.

Taxonomy

The genus Cnemarchus was introduced in 1905 by the American ornithologist Robert Ridgway with the red-rumped bush tyrant as the type species. The name combines the Ancient Greek knēmos meaning "mountain-slope" with arkhos meaning "ruler" or "chief".^[1]

This genus formerly contained only the red-rumped bush tyrant. Molecular phylogenetic studies published in 2020 found that the red-rumped bush tyrant was a sister to the rufous-webbed bush tyrant in the monotypic genus Polioxolmis. The two species had diverged around 4.5 million years ago.^[2][3] Based on these results, the genus Polioxolmis was merged into Cnemarchus placing both species in the genus Cnemarchus.^[4][5]

The genus therefore contains the following two species:^[5]

• Red-rumped bush tyrant (Cnemarchus erythropygius)
• Rufous-webbed bush tyrant (Cnemarchus rufipennis)