Marnus is a product of the Toyota Cheetah Academy. He made his #GuinnessPRO14 debut on the 8th September 2018 against Ospreys in Swansea.
He played his first game in the starting line-up on Saturday against Connacht in Galway.
Van der Merwe made his first starting appearance for the Toyota Cheetahs during against Connacht in Galway.
He was named in the squad to tour with the Cheetahs for their one-off match against the Glasgow Warriors