Image search confirms the "Tortoise" part; I couldn't find evidence that 'Plum Petite' exists. Though I suppose now I'm providing evidence that it exists, for anybody else who's searching Google, even though I'm not sure about it myself. Tricky how that works.
According to the tag, Masd. Tortoise is M. uniflora (solid pinkish-purple) x M. angulata (dull red-brown, variously spotted or solid depending on the specimen).