Out of curiosity, when, where and why did "salmo" become Oncorhynchus?   I grew up with Raiblow being Salmo Gairdnerii and now they are O. Mykiss ( my kiss, did Jimmy Houston name them).   Just one of them things consicering they still call Largemouth Bass, "troutlike fish with small fins"  "Micropterous Salmoides"

Well, I did a little looking and found out that Brownies and Atlantic Salmon are still "Salmo" so I am going to hazard a guess that it was decided that the Atlantic and Pacific species are different enough to warrant separation.  But then again, Cutts are still "Clarkii ", why did they change the species name of the Rainbow trout?  Since this is "Ask the Editors", maybe "ED " will step up.