Taxonomic complexities, like environmental plasticity and homoplasy, make precise identification challenging in Calamus, the genus of spiny climbing palms of the subfamily Calamoideae (Arecaceae). In the present study, the species discriminatory power of twelve potential DNA barcode regions (rbcL, matK, psbA-trnH, rpoC, rpoB, psbK-psbI, atpF-atpH, psbZ-trnfM, ITS1, ITS2, PRK, and RPB2) were evaluated in 21 species of Calamus from the Western Ghats region of India, using distance, tree, and similarity based statistical methods. Except for the low copy nuclear region, RPB2, none of the tested plastid loci or nuclear loci ITS, either singly or in combinations, could discriminate all the species of Calamus due to low substitution rate of plastid regions and multiple copies of ITS respectively. The RPB2 locus showed highest species resolution with 96% accuracy in similarity based analysis, indicating its potential and efficiency as a barcode locus for the genus. The putative “Calamus gamblei complex” based on overlapping morphology was successfully resolved as six distinct, though closely related, species. The analysis also indicates that C. delessertianus is a morphological variant of C. dransfieldii. In spite of being a low copy nuclear gene region, RPB2 provided an efficient barcode to delineate Calamus species and has the potential to further extend its use as a prospective barcode to other Palm genera.

中文翻译：

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低拷贝核区域 RPB2 作为一种新的 DNA 条形码区域，用于藤属菖蒲（Arecaceae）中的物种鉴定。

分类学的复杂性，如环境可塑性和同质性，使得在菖蒲（菖蒲亚科（Arecaceae）的多刺攀缘棕榈属）中进行精确识别具有挑战性。在本研究中，十二个潜在的 DNA 条形码区域（rbc L、mat K、psb A- trn H、rpo C 、rpo B 、psb K- psb I 、atp F- atp H、psb Z- trnf M、ITS1、ITS2、PRK 和 RPB2) 在 21 种菖蒲中进行了评估来自印度西高止山脉地区，使用基于距离、树和相似性的统计方法。除了低拷贝核区 RPB2 外，由于质体区的低取代率和 ITS 的多拷贝，没有一个测试的质体基因座或核基因座 ITS，无论是单独还是组合，都不能区分所有的菖蒲物种。RPB2 基因座在基于相似性的分析中显示出最高的物种分辨率，准确率为 96%，表明其作为该属条形码基因座的潜力和效率。基于重叠形态的推定“菖蒲复合体”被成功解析为六个不同但密切相关的物种。分析还表明C. delessertianus是C. dransfieldii的形态变异。尽管是一个低拷贝的核基因区域，但 RPB2 提供了一种有效的条形码来描述菖蒲物种，并有可能将其作为预期条形码的用途进一步扩展到其他棕榈属。