Specific status and species boundaries of several freshwater prawns in the Macrobrachium pilimanus species group remain ambiguous, despite the taxonomic re-description of type materials and additional specimens collected to expand the boundaries of some species. In this study, the “pilimanus” species group of Macrobrachium sensu Johnson (1958) was studied using specimens collected from montane streams of Thailand. Molecular phylogenetic analyses based on sequences of three molecular markers (COI, 16S and 18S rRNA) were performed. The phylogenetic results agreed with morphological identifications, and indicated the presence of at least nine putative taxa. Of these, six morphospecies were recognised as M. malayanum, M. forcipatum, M. dienbienphuense, M. hirsutimanus, M. eriocheirum, and M. sirindhorn. Furthermore, three morphologically and genetically distinct linages were detected, and are described herein as M. naiyanetri Siriwut sp. nov., M. palmopilosum Siriwut sp. nov. and M. puberimanus Siriwut sp. nov. The taxonomic comparison indicated wide morphological variation in several species and suggested additional diagnostic characters that are suitable for use in species diagnoses, such as the shape and orientation of fingers, the rostrum form, and the presence or absence of velvet pubescence hairs and tuberculated spinulation on each telopodite of the second pereiopods. The “pilimanus” species group was portrayed as non-monophyletic in both ML and BI analyses. The genetic structure of different geographical populations in Thailand was detected in some widespread species. The species delimitation based on the four delimitation methods (BIN, ABGD, PTP and GMYC) suggested high genetic diversity of the “pilimanus” species group and placed the candidate members much higher than in previous designations based on traditional morphology. This finding suggests that further investigation of morphological and genetic diversity of Southeast Asian freshwater prawns in the genus Macrobrachium is still required to provide a comprehensive species list to guide efforts in conservation and resource management.

中文翻译：

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淡水虾 Macrobrachium pilimanus 物种组的分子系统发育和物种界定，以及来自泰国的三个新物种的描述


尽管对模式材料进行了分类学重新描述并收集了额外的标本以扩大某些物种的边​​界，但毛虾沼虾物种组中几种淡水虾的具体状况和物种边界仍然不明确。在这项研究中，使用从泰国山地溪流采集的标本对 Macrobrachium sensu Johnson (1958) 的“pilimanus”物种组进行了研究。基于三个分子标记（COI、16S 和 18S rRNA）的序列进行了分子系统发育分析。系统发育结果与形态学鉴定一致，并表明存在至少九个假定的类群。其中，六个形态种被确认为 M. malayanum、M. forcipatum、M. dienbienphuense、M. hirsutimanus、M. eriocheirum 和 M. Sirindhorn。此外，检测到三个形态和遗传上不同的谱系，并在本文中描述为M. naiyanetri Siriwut sp。 11 月，M. palmopilosum Siriwut sp。十一月和 M. puberimanus Siriwut sp。十一月分类学比较表明几个物种存在广泛的形态变异，并提出了适用于物种诊断的附加诊断特征，例如手指的形状和方向、喙的形状以及是否存在天鹅绒状柔毛和结核状刺。第二步足的每个端肢。在 ML 和 BI 分析中，“pilimanus”物种组被描述为非单系群。在一些广泛分布的物种中检测到了泰国不同地理种群的遗传结构。 基于四种划界方法（BIN、ABGD、PTP和GMYC）的物种划界表明“pilimanus”物种组具有较高的遗传多样性，并且候选成员的排名远高于先前基于传统形态学的指定。这一发现表明，仍需要进一步调查东南亚淡水虾沼虾属的形态和遗传多样性，以提供全面的物种名录，以指导保护和资源管理工作。