How many protoctista species are there?

Protoctista, a diverse group within the domain Eukarya, includes a wide range of organisms such as algae, protozoa, and slime molds. Estimates suggest there are approximately 100,000 species of protoctists, but the exact number is difficult to determine due to ongoing discoveries and classifications. Many species remain undescribed, particularly in less-explored ecosystems. Thus, the total number of protoctista species could be significantly higher than current estimates.