The Schistura robertsi species complex is a group of freshwater fish inhabiting streams in southeast Myanmar as well as in western and southern Thailand. In southern Thailand, the distribution exceeds the biogeographically important ‘Surat Thani – Krabi line’. The complex is believed to include five described and one undescribed species, but monophyly and systematics of the group have never been studied explicitly. The present study aims to resolve the number of species within the Schistura robertsi group as well as their distribution areas and phylogenetic relations. We analysed mitochondrial and nuclear sequence data of 86 specimens from 47 localities and 18 morphological characters of 193 specimens. The phylogenetic analyses revealed the S. robertsi complex to be monophyletic and to be composed of ten major lineages. Six of them correspond to the known described or undescribed species, but another four newly identified clades reveal the existence of an overlooked diversity within the group. All genetic lineages are statistically highly supported and all are morphologically diagnosable, suggesting that they represent distinct species. The distribution areas of several clades overlap, the cases of direct co-occurrence show no sign of hybridisation.

该Schistura robertsi种复杂的是一组淡水鱼居住在缅甸东南部以及西部和南部泰国流。在泰国南部，分布范围超过了具有重要生物地理意义的“素叻他尼–甲米”系。据信该复合物包括五个已描述的物种和一个未描述的物种，但该类的单系和系统学尚未得到明确研究。本研究旨在解决Schistura robertsi组内的物种数量及其分布区域和系统发育关系。我们分析了47个地区的86个标本的线粒体和核序列数据，以及193个标本的18个形态特征。系统发育分析表明罗伯氏链球菌复合体是单一的，由十个主要谱系组成。其中六个对应于已知的已描述或未描述的物种，但另外四个新发现的进化枝则揭示了该群体中存在被忽视的多样性。统计上高度支持所有遗传谱系，并且在形态学上都可对其进行诊断，表明它们代表不同的物种。多个进化枝的分布区域重叠，直接共生的情况没有杂交迹象。