There has been quite a debate around tetraspis and speciosa. I personnaly think they are the same species.
I think Phal tetraspis is supposed to be named Phal speciosa now. I grow a few speciosa, and last time I spoke with my resource from Taiwan I was told that the proper name for Phal tetraspis C#1 is actually P speciosa var. christiana.
One thing is for sure, if they aren't the same, they re closely related!