From historical expedition diaries to whole genome sequencing: A case study of the likely extinct Red Sea torpedo ray

Torpedo rays (Torpedinidae, Torpediniformes) are small to moderately large batoids that produce an electric discharge. They are distributed worldwide in temperate and tropical seas and are, as a result of their bottom-dwelling behaviour, susceptible to trawl fishing and often end up as victims of bycatch. The distribution ranges of most recognized species seem to be restricted; however, their species-level systematics is not adequately resolved.

In the genus Torpedo, in which many species require revision, there are possibly several undescribed species, while numerous misidentifications add to the complexity of the issue. In the latest lists of living rays, 13 species are accepted in the genus Torpedo, including three of doubtful validity and several recently discovered undescribed species. Among the valid species is the critically endangered, possibly extinct, Torpedo suessii Steindachner, 1898, the Red Sea torpedo, of which only four specimens have been recorded in the literature until now, three of which still exist in the fish collection of the Natural History Museum of Vienna.

Museum collections are the most important archive of biodiversity on Earth, and are increasingly being used for various studies, including phylogenetics, population genomics, and biogeography. Nevertheless, molecular analysis of old museum material remains challenging because the genetic material has degraded, is fragmented, and of low quantity. In molecular taxonomy, the necessity of including type specimens as name-bearing specimens is increasingly recognized.

Here, the extended specimen approach was applied to re-describe the lectotype of T. suessii. The approach included research of historical information and whole genome sequencing, followed by genome assembly and phylogenetic analysis. K E Y W O R D S extended specimen approach, historical DNA, Torpedo, type material This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.