While the 1888 Commission Rifle was not a Mauser product, I think there is a very strong likelihood that the cartridge itself was developed by Mauser.
At the time Mauserwerk was probably the most active and significant cartridge development entity on the planet.
Based on other development work going on at Mauser at the time, such as with the rifle that would become the Belgian 1889 Mauser, it would appear that Mauserwerk was working with the concept of rimless cartridges at least as early as 1886, possibly even earlier.
It's also possible that the concept sprang up elsewhere in Europe, perhaps at the hands of Col. Rubin's work with what would become the 7.5x55 Swiss.
Or, it's also possible that, with the development of smokeless powder finally solving the chamber fouling problem, that it was one of those ideas whose time had come and it sprang up independently in several places all at once.
But I put my money on Mauserwerk.
"The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza
Baby Jesus cries when the fat redneck doesn't have military-grade firepower.