Cryptic species in a colorful genus: integrative taxonomy of the bush robins (Aves, Muscicapidae, Tarsiger) suggests two overlooked species

Several cryptic avian species have been validated by recent
integrative taxonomic efforts in the Sino-Himalayan mountains, indicating
that avian diversity in this global biodiversity hotspot may be
underestimated. In the present study,we investigated species limits in the
genus Tarsiger, the bush robins, a group of montane forest
specialists with high species richness in the Sino-Himalayan region. Based
on comprehensive sampling of all 11 subspecies of the six currently
recognized species, we applied an integrative taxonomic approach by
combining multilocus, acoustic, plumage and morphometric analyses. Our
results reveal that the isolated north-central Chinese populations
of Tarsiger cyanurus, described as the
subspecies albocoeruleus but usually considered invalid,
is distinctive in genetics and vocalisation, but only marginally
differentiated in morphology. We also found the Taiwan endemic T.
indicus formosanus to be distinctive in genetics, song and
morphology from T. i. indicus and T.
i. yunnanensis of the Sino-Himalayan mountains.
Moreover, Bayesian species delimitation using BPP suggests that
both albocoeruleus and formosanus merit full species status. We propose their treatment as ‘Qilian Bluetail’ T. albocoeruleus and ‘Taiwan Bush Robin’ T. formosanus, respectively.

近期在中国-喜马拉雅山脉开展的整合分类学（integrative taxonomy）研究已证实若干隐秘鸟类物种的存在，表明该全球生物多样性热点区域的鸟类多样性可能被低估。本研究针对鸲属（Tarsiger，林鸲）的物种界定（species limits）展开调查，该属为山地森林特化种，在中国-喜马拉雅区域具有较高物种丰富度。基于对当前公认的6个物种全部11个亚种的全面采样，我们结合多位点（multilocus）、鸣声（acoustic）、羽色（plumage）及形态测量（morphometric）分析，采用整合分类学方法研究。结果显示，中国中北部的蓝眉林鸲（Tarsiger cyanurus）孤立种群——曾被描述为亚种albocoeruleus但通常被认为无效——在遗传和鸣声上具显著特征，但形态差异微小。我们还发现，台湾特有的台湾林鸲亚种（T. indicus formosanus）在遗传、鸣声及形态上与中国-喜马拉雅山脉的指名亚种（T. i. indicus）和云南亚种（T. i. yunnanensis）存在显著差异。此外，利用BPP进行的贝叶斯物种界定（Bayesian species delimitation）结果表明，albocoeruleus和formosanus均应被赋予完全物种地位（full species status）。我们建议将它们分别分类处理为‘祁连山蓝尾鸲’（T. albocoeruleus）和‘台湾林鸲’（T. formosanus）。