﻿AbstractThe taxonomy of the endemic whitefish of the lakes of the Reuss River system (Lucerne, Sarnen, Zug) and Lake Sempach, Switzerland, is reviewed and revised. Lake Lucerne harbours five species.Coregonusintermundiasp. nov.andC.suspensussp. nov., are described.CoregonusnobilisHaack, 1882,C.suidteriFatio, 1885, andC.zugensisNüsslin, 1882, are redescribed. Genetic studies have shown thatC.suidteriandC.zugensisare composed of several distinct species endemic to different lakes. The namesC.suidteriandC.zugensisare restricted to the species of lakes Sempach and Zug, respectively. The whitefish populations previously referred to asC.suidteriandC.zugensisfrom Lake Lucerne are described asC.litoralissp. nov.andC.muellerisp. nov., respectively. Furthermore, the whitefish from Lake Zug that were previously referred to asC.suidteriare described asC.supersumsp. nov. A holotype is designated forC.supersumthat was previously one of two syntypes ofC.zugensis. The other syntype is retained forC.zugensis.Coregonusobliterussp. nov.is described from Lake Zug, andC.obliterusandC.zugensisfrom Lake Zug are extinct. Finally, we describeC.sarnensissp. nov.from lakes Sarnen and Alpnach.Coregonussuidterifrom Lake Sempach shows strong signals of introgression from deliberately translocated non-native whitefish species, which questions if the extant population still carries a genetic legacy from the original species and thus may need to be considered extinct.Coregonussuspensusis genetically partially of allochthonous origin, closely related to the radiation of Lake Constance. It is therefore compared to all known and described species of Lake Constance:C.wartmanniBloch, 1784,C.macrophthalmusNüsslin, 1882,C.arenicolusKottelat,1997, andC.gutturosusGmelin, 1818.