Why several when one can unite them all? Integrative taxonomic revision of Indo-Pacific freshwater pipefish (Nerophinae)

The family Syngnathidae (seahorses, sea dragons and pipefishes) is a fascinating group. Species are mostly distributed in marine coastal waters, but about 30 species inhabit Indo-Pacific tropical island rivers. There are currently six freshwater genera of Nerophinae (trunk-brooders): Belonichthys, Coelonotus, Doryichthys, Lophocampus, Microphis and Oostethus. Unlike other Syngnathidae, freshwater pipefish have been little studied; the taxonomy of Nerophinae is unclear and only based on morphomeristic data. The purpose of our study is to undertake a revision of this group based on an integrative taxonomy approach. By combining molecular data from four mitochondrial markers (5415 bp), morphomeristic data with a character mapping study and ecological data, we now recognize a single genus as valid, Microphis, as opposed to the six previously accepted. Our results also reveal one new candidate species, Microphis nicoleae sp. nov., and the resurrection of two others: Microphis torrentius and Microphis vaillantii. This study shows the relevance of integrative taxonomy for higher taxa delineation, using data integration by congruence.

Automated summary

The family Syngnathidae is intriguing, with most species found in marine coastal waters, but about 30 species inhabit rivers on Indo-Pacific tropical islands. Freshwater pipefish within the family have been under-studied, and the taxonomy of Nerophinae is still uncertain. This study demonstrates the importance of integrative taxonomy in redefining higher taxa, using a combination of molecular, morphological, and ecological data.