Many of the large flowered clematis have been a mix of crossing different species up to the point that they are no longer a species. They are broadly referred to as Hybrid Clematis or sometimes known as Jackmanii Hybrids.
From Wikipedia: Clematis ‘Jackmanii’ is a Clematis cultivar which, when it was introduced in 1862, was the first of the modern large-flowered hybrid clematises of gardens. It is a climber with large violet-purple blooms, still among the most familiar climbers seen in gardens. It was produced from crosses made by the prominent nurseryman George Jackman (1837–1887), of Jackman & Sons, Woking, Surrey.