The P. Curtus (aka black blood) has at least 3, maybe 4 distinct color phases. They go by so many nick names, and other common names...
The first that most people think of when they hear black blood is the Black Head. ( Aka, Dark Head).
The second is the Chrome heads (aka, light head).
Third is the Yellow/ Orange heads (although they may be light heads, but are so starkly different I can't see how they are one in the same)
Then the Caramel Albino morph, which has been reproduced by Tracy Barker of VPI.
Don't know if you have browsed, but we have a dark and light head p. curtus, I think it's pretty apparent that the light heads show more pattern.