While visiting the Herbarium of the Botany Department of the National Museum of the Federal University of Rio de Janeiro (code, R), we located the types of 219 bryophyte names, most of which were published by Karl Müller (cited as Müller Hallensis), whose holotypes were lost during the bombing of the Berlin Herbarium in 1943. A total of 181 names (82%) are possible candidates for lectotypification and most likely not to be found elsewhere. We also found the complete collection of Müller's "Bryologia Serrae Itatiaiae", made by Ernst Ule.