What is the difference between kingdoms protistae and protoctistae?

Question

I understand that both kingdoms represent primitive eukaryotic organisms, and both contain both unicellular and multicellular organisms.

What are the points that distinguish one kingdom from the other?

Answer 1

First, just a correction: it's "Protista" and "Protoctista", not "Protistae" and "Protoctistae".

They mean the same thing. Those are just different names proposed by different taxonomists for describing the same group of organisms.

• Protoctista (or Primigenum) was proposed by John Hogg in 1860.
• Protista was proposed by Ernst Haeckel in 1866.

However, as it is common in taxonomy and nomenclature in general, things sometimes get a bit more complicated: some biologists, like Lynn Margulis, don't treat those two terms as synonyms. Particularly, I don't use her nomenclature.

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Source:

• Jstor.org. (2017). Protozoa, Protista, Protoctista: What's in a Name? on JSTOR. [online] Available at: http://www.jstor.org/stable/4331095 [Accessed 12 Sep. 2017].