NEMACHEILUS PEZIDION 2022

Endemic To Laos

This species of loach was frst collected in 1999 in the Xe Kong watershed in Attapeu province in southern Laos. It was originally identifed as Nemacheilus longistriatus, but in 2022 it was confrmed as a new species. It is distinguished from the nearly 800 other fshes in the stone loach family (Nemacheilidae) by its unique colour pattern consisting of a black stripe along its side and 11–15 narrow saddles across its back.

Swiss ichthyologist Maurice Kottelat frst came across the species while researching a book on the fshes of Laos. Sampling expeditions in various habitats across the country yielded around 60 new species – but with so many others discovered, this one slipped through the net.

“At frst the fsh was identifed as N. longistriatus but it looked somewhat diferent, and I put it aside to look at it in detail later,” said Kottelat. “It was only recently, when preparing a new edition of my book, that I looked at it in more detail and confrmed it is a distinct species.”

To date, the species has only been recorded in the lower part of the Xe Pian watershed. It is likely to have been afected by the collapse, in 2018, of a major dam on the Xe Pian river, which caused catastrophic fooding. “All the sites where we collected the species seem to have been impacted,” said Kottelat. “As far as I know, nobody has checked which of the native fauna of Xe Pian is still present.”

Kottelat, M. (2022). Nemacheilus pezidion, a new species of loach from southern Laos (Teleostei: Nemacheilidae). Zootaxa 5129(1): 92-104. doi. org/10.11646/zootaxa.5129.1.5