Previous studies have indicated the occurrence of nine species of Palaemon in Brazil. However, the extensive variability in their diagnostic characters and the geographic distribution of some species raises doubts about the validity of some taxa, potentially indicating the occurrence of species not yet reported from Brazil or even not described. To solve taxonomic issues with Palaemon species in Brazil, we carried out a multigene analysis by using partial fragments of 16S and COI mitochondrial genes and the nuclear H3. Phylogenetic relationships were inferred by maximum likelihood and Bayesian inference. The external morphology corresponding to the terminal clades obtained in the molecular phylogram was analysed to identify diagnostic characters that allow the recognition of the groups and the correct taxa assignment. The combined analysis of molecular and morphological data confirms the existence of nine species of Palaemon in Brazil, five from the “Palaemon” lineage (P. mercedae and four Palaemon stensu stricto—P. argentinus, P. octaviae—first record in Brazil, P. northropi and P. paivai) and four of the “Alaocaris” lineage (P. carteri, P. ivonicus, P. pandaliformis and P. yuna). The possibility of further cryptic speciation is also pointed out. In addition to confirming the validity of the nine species, the results indicate the need for taxonomic adjustments and corresponding changes in the geographic distribution of Palaemon species occurring in Brazil.

中文翻译：

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巴西Palaemon（十足目，Palaemonidae）物种分类地位的分子和形态学方法

先前的研究表明巴西有九种Palaemon。然而，它们的诊断特征和某些物种的地理分布的广泛可变性引起了对某些分类群的有效性的怀疑，这可能表明巴西尚未报告甚至未描述的物种的出现。为了解决巴西Palaemon物种的分类问题，我们通过使用16S和COI线粒体基因的部分片段以及核H3进行了多基因分析。通过最大似然和贝叶斯推理推断系统发育关系。分析与分子系统图中获得的末端进化枝相对应的外部形态，以识别允许识别组和正确分类群分配的诊断特征。分子和形态学数据的综合分析证实了巴西存在 9 种帕拉蒙，其中 5 种来自“帕拉蒙”谱系（P. mercedae 和四种严格的 Palaemon stensu-P. argentinus、P. Octaviae—巴西首次记录，P . northropi 和 P. paivai）和四个“Alaocaris”谱系（P. carteri、P. ivonicus、P. pandaliformis 和 P. yuna）。还指出了进一步神秘物种形成的可能性。除了确认这九个物种的有效性外，结果还表明需要进行分类调整，并相应地改变发生在巴西的 Palaemon 物种的地理分布。Octavie——巴西第一记录，P. northropi 和 P. paivai）和四个“Alaocaris”谱系（P. carteri、P. ivonicus、P. pandaliformis 和 P. yuna）。还指出了进一步神秘物种形成的可能性。除了确认这九个物种的有效性外，结果还表明需要进行分类调整，并相应地改变发生在巴西的 Palaemon 物种的地理分布。Octavie——巴西第一记录，P. northropi 和 P. paivai）和四个“Alaocaris”谱系（P. carteri、P. ivonicus、P. pandaliformis 和 P. yuna）。还指出了进一步神秘物种形成的可能性。除了确认这九个物种的有效性外，结果还表明需要进行分类调整，并相应地改变发生在巴西的 Palaemon 物种的地理分布。