Belostoma is the most diverse genus of Belostomatidae, comprising 74 species. The small Belostoma species are challenging to identify mainly due to the presence of cryptic species. As DNA barcoding has been a crucial tool to solve the taxonomic impediment associated with many taxa, we compared species delimitations obtained by morphological and molecular approaches, in order to help to disentangle the taxonomy of Belostoma. We sampled 192 specimens of Belostoma across the Rio Grande do Sul Brazilian Coastal Plain. Specimens were first identified with the use of morphological markers and then characterized for two mitochondrial markers: cytochrome C oxidase subunit I (COI) and 16S rRNA genes, generating 181 and 164 sequences, respectively. These were complemented with Belostoma sequences downloaded from NCBI/BOLD (101 for COI & 13 for 16S). Thus, matrixes including 282, 177 and 299 sequences for COI, 16S and the concatenated data set, respectively, were analysed through phylogenetic, phylogeographic and distance approaches. The initial morphological evaluation allowed the identification of 14 male genitalia morphotypes, whose sequences were added to a preliminary matrix containing ​NCBI/BOLD sequences of five other described species, allowing us to recover 10 clades in the molecular analyses. Patterns of reciprocal monophyly were confirmed for only six of the studied species: Belostoma angustum, Belostoma cummingsi, Belostoma dentatum, Belostoma noualhieri, Belostoma orbiculatum and Belostoma ribeiroi. Belostoma candidulum, Belostoma horvathi and Belostoma sanctulum appeared intermingled in a single clade. The grouping of these with the other five distinct (male genital) morphotypes reveals a clade with high levels of morphological polymorphism or phenotypic plasticity.

中文翻译：

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借助 DNA 条形码方法解开 Belostoma Latreille（半翅目：Belostomatidae）的分类

Belostoma是Belostomatidae中最多样化的属，包括 74 个物种。主要由于隐匿物种的存在，小型Belostoma物种难以识别。由于 DNA 条形码已成为解决与许多分类群相关的分类障碍的重要工具，我们比较了通过形态学和分子方法获得的物种界限，以帮助解开Belostoma的分类学。我们采集了 192 个Belostoma标本横跨南里奥格兰德巴西沿海平原。首先使用形态学标记对标本进行鉴定，然后对两种线粒体标记进行表征：细胞色素 C 氧化酶亚基 I (COI) 和 16S rRNA 基因，分别产生 181 和 164 个序列。这些与Belostoma 相辅相成从 NCBI/BOLD 下载的序列（COI 为 101，16S 为 13）。因此，通过系统发育、系统地理学和距离方法分析了分别包括 COI、16S 和串联数据集的 282、177 和 299 序列的矩阵。最初的形态学评估允许鉴定 14 种男性生殖器形态型，其序列被添加到包含 NCBI/BOLD 序列的其他五个描述物种的初步矩阵中，使我们能够在分子分析中恢复 10 个进化枝。仅在六个研究物种中证实了相互单系的模式：Belostoma angustum、Belostoma cummingsi、Belostoma dentatum、Belostoma noualhieri、Belostoma orbiculatum和B elostoma ribeiroi。Belostoma candidulum、Belostoma horvathi和Belostoma sanctulum出现在单个进化枝中。这些与其他五种不同（男性生殖器）形态类型的分组揭示了具有高水平形态多态性或表型可塑性的进化枝。