Protoctista?

[Fortuner]

In an encyclopedia I read the following: "Protozoa and algae belong to
the kingdom Protoctista." I would like to know:
- is this Protoctista the same as the protista?
- if the same, why the extra letters?
- if not the same, what's the difference?
Of course, it might just be a spelling mistake!

Thanks
--
Renaud Fortuner
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