Data from: Barcoding snakeheads (Teleostei, Channidae) revisited: discovering greater species diversity and resolving perpetuated taxonomic confusions

Snakehead fishes of the family Channidae are predatory freshwater teleosts from Africa and Asia comprising 38 valid species. Snakeheads are important food fishes (aquaculture, live food trade) and have been introduced widely with several species becoming highly invasive. A channid barcode library was recently assembled by Serrao and co-workers to better detect and identify potential and established invasive snakehead species outside their native range. Comparing our own recent phylogenetic results of this taxonomically confusing group with those previously reported revealed several inconsistencies that prompted us to expand and improve on previous studies. By generating 343 novel snakehead coxI sequences and combining them with an additional 434 coxI sequences from GenBank we highlight several problems with previous efforts towards the assembly of a snakehead reference barcode library. We found that 16.3% of the channid coxI sequences deposited in GenBank are based on misidentifications. With the inclusion of our own data we were, however, able to solve these cases of perpetuated taxonomic confusion. Different species delimitation approaches we employed (BIN, GMYC, and PTP) were congruent in suggesting a potentially much higher species diversity within snakeheads than currently recognized. In total, 90 BINs were recovered and within a total of 15 currently recognized species multiple BINs were identified. This higher species diversity is mostly due to either the incorporation of undescribed, narrow range, endemics from the Eastern Himalaya biodiversity hotspot or the incorporation of several widespread species characterized by deep genetic splits between geographically well-defined lineages. In the latter case, over-lumping in the past has deflated the actual species numbers. Further integrative approaches are clearly needed for providing a better taxonomic understanding of snakehead diversity, new species descriptions and taxonomic revisions of the group.

鳢科（Channidae）的鳢类（Snakehead fishes）是分布于非洲与亚洲的掠食性淡水真骨鱼类，目前共包含38个有效物种。鳢类是重要的食用鱼类，涉及水产养殖与活体贸易领域，且被广泛引种至全球多地，其中多个物种已成为极具入侵性的类群。塞拉奥（Serrao）及其合作者近期构建了一套鳢科条形码数据库，以更好地检测和识别其原生分布范围之外的潜在入侵及已定植的入侵鳢类物种。将本团队近期针对这一分类学疑难类群的系统发育研究结果与已有文献报道进行比对后，我们发现多处不一致之处，这促使我们对既往研究进行拓展与优化。本研究新生成343条鳢类细胞色素氧化酶亚基I（cytochrome c oxidase subunit I，简称coxI）基因序列，并将其与GenBank数据库中额外获取的434条coxI序列进行整合，由此揭示了既往构建鳢类参考条形码文库工作中存在的若干问题。我们发现，GenBank中提交的鳢科coxI序列有16.3%是基于错误鉴定的样本得到的。然而，纳入本研究的数据后，我们得以解决这些长期存在的分类学混淆问题。本研究采用的多种物种界定方法（BIN、GMYC、PTP）均一致表明，鳢类的物种多样性可能远高于当前已认知的水平。最终共检索得到90个条形码索引号（Barcode Index Number，简称BIN），且在当前已确认的15个物种中，均鉴定出多个BIN。这种更高的物种多样性主要源于两类情况：一是纳入了东喜马拉雅生物多样性热点区域中尚未被正式描述、分布范围狭窄的特有物种；二是纳入了多个广布物种，这些物种在地理上界限分明的支系间存在深度遗传分化。在后一种情况中，既往研究中的过度归并行为实际上压低了真实的物种数量。显然，未来亟需采用更为综合的研究方法，以实现对鳢类物种多样性的更深入认知、新物种的描述以及该类群的分类学修订。