Phylogenetic analysis of museum specimens of houting Coregonus oxyrinchus shows the need for a revision of its extinct status

R. Kroes, Y. Winkel, J. A. J. Breeuwer, E. E. van Loon, S. P. Loader, J. S. Maclaine, P. F. M. Verdonschot, H. G. van der Geest

According to the IUCN Red List the anadromous houting Coregonus oxyrinchus is categorized as 'extinct'. However, this extinct status might be incorrect because taxonomic difference between C. oxyrinchus and the closely related C. lavaretus is based on a disputable morphological comparison. Also, phylogenetic studies on mtDNA only focused on recent obtained coregonids. We are the first to perform a mtDNA analysis on both historic and recent specimens, including the syntype specimen which was used for species description by Linnaeus originally. Two primer pairs for mitochondrial CytB and ND3 were used to extract sequences for phylogenetic analysis. Sequences from 14 out of 21 C. oxyrinchus museum specimens were successfully obtained and compared with sequences from recent obtained C. lavaretus. The sequences were combined with GenBank data from a previous phylogenetic study on houting to create a phylogenetic tree and two minimum spanning haplotype networks. Results show that C. oxyrinchus and C. lavaretus form a clade with limited genetic variation. Low bootstrap values also show weak support for geographical patterns in distribution of mitochondrial haplotypes. Statistical analysis of the haplotype networks also shows that historic and recent specimens are similar species. Our results suggest that C. oxyrinchus is a junior synonym of C. lavaretus. A definitive taxonomic revision could not be made because only CytB sequencing was successful for the syntype specimen. We discuss taxonomic consequences and the species-specific focus in nature conservation. We propose a shift in nature conservation to a more functional approach based on traits rather than species.