I recently realized that a number of Rosularia were moved to the Prometheum genus, like P. chrysanthum, P. muratdaghense, and P. serpentinica. Apparently Prometheum differs from Rosularia in "the absence of a well-developed caudex, the cymose instead of paniculate inflorescence, the usually less connate petals and the lack of ciliae along the leaf margins" (Illustrated Handbook of Succulent Plants: Crassulaceae by Eggli, 2012).
Does anyone know when this change happened? And do you find it's been adopted by gardeners and nurseries, or are people holding on to the old Rosularia name?