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Research article - Peer-reviewed, 2016

Integrative taxonomy of the Plain‑backed Thrush (Zoothera mollissima) complex (Aves, Turdidae) reveals cryptic species, including a new species

Alström, Per; Olsson, Urban


The Plain-backed Thrush Zoothera mollissima breeds in the Himalayas and mountains of central China.It was long considered conspecific with the Long-tailed Thrush Zoothera dixoni, until these were shown to be broadlysympatric.

We revise the Z. mollissima-Z. dixoni complex by integrating morphological, acoustic, genetic (two mitochondrialand two nuclear markers), ecological and distributional datasets.

In earlier field observations, we noted two very different song types of "Plain-backed" Thrush segregated by breeding habitat and elevation. Further integrative analyses congruently identify three groups: an alpine breeder inthe Himalayas and Sichuan, China ("Alpine Thrush"); a forest breeder in the eastern Himalayas and northwest Yunnan(at least), China ("Himalayan Forest Thrush"); and a forest breeder in central Sichuan ("Sichuan Forest Thrush"). Alpine and Himalayan Forest Thrushes are broadly sympatric, but segregated by habitat and altitude, and the same is probablytrue also for Alpine and Sichuan Forest Thrushes. These three groups differ markedly in morphology and songs.In addition, DNA sequence data from three non-breeding specimens from Yunnan indicate that yet another lineage exists ("Yunnan Thrush"). However, we find no consistent morphological differences from Alpine Thrush, and its breedingrange is unknown. Molecular phylogenetic analyses suggest that all four groups diverged at least a few million years ago, and identify Alpine Thrush and the putative "Yunnan Thrush" as sisters, and the two forest taxa as sisters. Cytochrome b divergences among the four Z. mollissima sensu lato (s.l.) clades are similar to those between any ofthem and Z. dixoni, and exceed that between the two congeneric outgroup species. We lectotypify the name Oreocincla rostrata Hodgson, 1845 with the Z. mollissima sensu stricto (s.s.) specimen long considered its type. No availablename unambiguously pertains to the Himalayan Forest Thrush.

The Plain-backed Thrush Z. mollissima s.l. comprises at least three species: Alpine Thrush Z. mollissima s.s., with a widespread alpine breeding distribution; Sichuan Forest Thrush Z. griseiceps, breeding in central Sichuan forests; and Himalayan Forest Thrush, breeding in the eastern Himalayas and northwest Yunnan (at least), which is described herein as a new species. "Yunnan Thrush" requires further study.


Systematics, Morphology, Bioacoustics, Altitudinal distributions, Genetic distances, Undescribed taxa, Zoothera dixoni, Lectotypification, Holotype

Published in

Avian Research
2016, volume: 7, article number: UNSP 1

Authors' information

Chinese Academy of Sciences
Uppsala University
Swedish University of Agricultural Sciences, Swedish Species Information Centre
Olsson, Urban
University of Gothenburg

UKÄ Subject classification

Biological Systematics
Evolutionary Biology
Bioinformatics and Systems Biology

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