Wednesday, January 27, 2016

A new thrush: Zoothera salimalii

New bird species are rarely discovered nowadays. In the last 15 years, approximately five new species have been discovered annually on average, mainly in South America. 

A new species from north-eastern India and adjacent parts of China was first discovered when it was realised that what was considered a single species, the Plain-backed Thrush Zoothera mollissima, was in fact two different species. What first caught the attention of the scientists was the fact thrushes in the coniferous and mixed forest had a rather musical song. This was in contrast to individuals found on bare rocky ground above the treeline in the same area, as they had a much harsher, scratchier, more unmusical song. The Himalayan Forest Thrush (Zoothera salimalii) is locally common. It has just been overlooked until now because of its close similarity in appearance to the Alpine Thrush.

The new species was named after Dr S├ílim Ali, in honor of his contributions to the development of Indian ornithology and conservation.

For the experts: 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 in the 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 probably true 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 breeding range 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 of them 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 available name unambiguously pertains to the Himalayan Forest Thrush.

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