Re-description and phylogenetic relationships of †Protosyngnathus sumatrensis (Teleostei: Syngnathoidei), a freshwater pipefish from the Eocene of Sumatra, Indonesia

Abstract

†Protosyngnathus sumatrensis is known from six specimens from Eocene lacustrine deposits of the Sangkarawang Formation of Sumatra, Indonesia. The fish was named almost 150 years ago, but has never been well described or figured. Probably because of this, it has not been included in phylogenies of extant pipefishes and seahorses (Syngnathiformes). A detailed description is provided, along with a new phylogenetic analysis of morphological characters that allows the Eocene fish to be confidently placed with the extant families Syngnathidae (pipefishes and seahorses) and Solenostomidae (ghost seahorses) along with the Paleocene marine fossil †Eekaulostomus cuevasae from Mexico. The vast majority of these fishes are marine inhabitants, with a few syngnathids entering brackish or freshwater habitats. †Protosyngnathus documents the occurrence of syngnathiform fishes in a lacustrine environment, indicating that this lineage invaded and became adapted to the freshwater environment early in the evolution of this group.

Keywords:

• Eocene
• Indonesia
• Gasterosteiformes
• Protosyngnathidae
• Syngnathifomes

Acknowledgements

My thanks to Manuel Röthel, Ronald Winkler and Markus Wilmsen, Senckenberg Naturhistorische Sammlungen Dresden, Museum für Mineralogie und Geologie, and Emma Bernard, Natural History Museum, London, for access to material in their care and help during my visits and for providing photographs of the material. Thanks also to the editor (Z. Johanson) and reviewers (K. Cantalice and an anonymous reviewer) for their helpful comments, which improved the manuscript. The photographs used in this paper were taken by the author except for the one in Figure 2, which was provided by E. Bernard and used with her permission. Funding for this research was provided by a Natural Sciences and Engineering Research Council of Canada Discovery Grant [327448] to the author.

Supplemental material

Supplemental material for this article can be accessed here: http://dx.doi.org/10.1080/14772019.2022.2113832.

Associate Editor: Erin Maxwell