The wren-babbler genus Pnoepygia is usually grouped into two species pairs, one pair from high altitude in forested mountains of the Chinese Himalayas and Taiwan, the other from lower elevations in the same regions, extending into South-East Asia and The Sundas, Indonesia. Analysis of the vocalisations and genetics of the four accepted species has identified a distinct lineage of Scaly-breasted Wren-babbler P albiventer in China, which researchers suggest is a separate species, P mutica.
The research team noted that intraspecific variation of both molecules and calls in P albiventer was conspicuous among individuals from Nepal and those from the Chinese provinces of Sichuan and Hubei. A third distinct genetic lineage of P. albiventer was found in Myanmar. They proposed that that the Chinese form be ranked as a separate species P mutica Thayer and Bangs, 1912, a name which was previously thought to be a synonym of P albiventer.
Päckert, M, Martens, J, Liang, W, Hsu, Y-C, and Sun, Y-H. 2013. Molecular genetic and bioacoustic differentiation of Pnoepyga Wren-babblers. Journal of Ornithology 154: 329-337.