Common Scaly Thrush (Zoothera dauma) - HBW 10, p. 693

Taxonomy: Turdus Dauma Latham, 1790, Kashmir, India.
Forms a group, possibly a superspecies, with Z. imbricata, Z. lunulata, Z. heinei, Z. machiki, Z. talaseae, Z. margaretae, Z. turipavae, Z. monticola and Z. marginata, perhaps including also Z. mollissima and Z. dixoni. First four, at least, of these previously considered conspecific with present species, and Z. lunulata possibly better treated as such. Taxonomy highly fluid and confusing, and various recent arrangements have been attempted. Migratory races aurea and toratugumi often split off as a separate species, apparently very distinct vocally from nominate; and resident major, horsfieldi and neilgherriensis separated as three further species, although last-mentioned may belong with Z. imbricata. Race major has for two decades been treated as separate owing to its vocal differences from aurea and toratugumi, but it is vocally close to nominate, and the seeming intergradation in SE Asia of certain plumage characters demarcating nominate and aurea represents a problem that also affects the status of horsfieldi, although latter is mensurally distinctive (but sings like aurea). Thus, if voice used as a decisive taxonomic character, equatorial horsfieldi may be judged conspecific with N aurea, and Japanese major with (mainly Himalayan) nominate. Furthermore, resident population on Iriomote Jima (in S Ryukyu Is) apparently belongs to an undescribed race, while resident population on Taiwan, often treated within horsfieldi, remains racially indeterminate. Considerable effort required to assemble and analyse extensive specimen and vocal evidence before a strong case can be made for any one arrangement over another. Six subspecies currently recognized. Also breeds (racial identities unsettled) on Iriomote Jima (S Ryukyu Is) and Taiwan.