 The species was first described scientifically under the name Ixocomus sibiricus by American mycologist Rolf Singer in 1938 , based on material that was collected under Pinus <unk> var. sibirica in the Altai Mountains of central Asia . In 1945 , he transferred it to Suillus . Alexander H. Smith called the species Boletus sibiricus in 1949 , but this is today considered a synonym . Singer named the subspecies S. sibiricus subsp. helveticus in 1951 , based on material collected by Jules Favre from Switzerland in 1945 . Roy Watling later considered this a nomen nudum — not published with an adequate description , and therefore failing to qualify as a formal scientific name . 
