In the foothill zone - Sabanejewia balcanica (Karaman 1922), in the lowland zone - Sabanejewia bulgarica (Drensky 1928): myth or reality?

The status of golden loaches (genus Sabanejewia) in the region of Central Europe and Balkans is still ambiguous. The greatest controversy is caused by species Sabanejewia balcanica and S. bulgarica, whose distinguishing features are often difficult to prove and their occurrence in some river sections is often mentioned as sympatric. Previous phylogenetic studies aimed at the resolving of their taxonomic status did not include samples from their type localities and so led to a lack of their true distribution in this region. Therefore, the main aim of this study was to identify the taxonomic status of golden loaches populations in this area on the model territory of Slovakia. For this purpose, we used a novelty approach (morphological, molecular and microhabitat) and we also included the missing samples from the type localities of both species. Based on mtDNA all the Slovakian samples reflected haplotype richness revealed on the type locality of S. bulgarica, although the genetic distances from other representatives of the genus Sabanejewia occurring are not significant. Within the morphology, we have revealed a great measure of variability in studied populations, which is largely caused by different habitat conditions and thus representing a phenotypic plasticity of these fish.

Methods
Table_S1 Detail list of all studied taxa, their haplotype classification to sampling sites, haplotype frequencies and GenBank accession numbers.

Table_S2 Summary of genetic diversity indices and results of neutrality tests in the cyt b dataset

Table_S3 Support values of the nodes according to two delimitation methods and three phylogenetic analyses

中欧与巴尔干地区的金色鳅属（Sabanejewia）鱼类的生存现状仍不明确。其中争议最大的是巴尔干金色鳅（Sabanejewia balcanica）与保加利亚金色鳅（S. bulgarica），二者的鉴别特征往往难以界定，且部分河段中二者被多次报道同域分布。此前旨在厘清其分类地位的系统发育研究，均未纳入这两个物种的模式产地样本，因此导致该区域内它们的真实分布情况至今不明。因此本研究以斯洛伐克为典型研究区域，旨在明确该区域内金色鳅种群的分类地位。本研究采用形态学、分子生物学与微生境分析相结合的创新研究方法，同时补充了两个物种模式产地的缺失样本。基于线粒体DNA（mtDNA）的分析结果显示，所有斯洛伐克样本均呈现出与保加利亚金色鳅模式产地一致的单倍型丰富度，尽管该属其他类群间的遗传距离并未达到显著水平。在形态学维度，本研究发现所调研的种群存在显著的形态变异，该变异主要由不同的生境条件所导致，反映了这些鱼类的表型可塑性。

方法
表S1 所有研究类群的详细列表、其采样位点的单倍型分类、单倍型频率及GenBank登录号。
表S2 细胞色素b（cyt b）数据集的遗传多样性指数汇总与中性检验结果。
表S3 基于两种物种界定方法与三种系统发育分析得到的节点支持值。