Step 1: Understanding the Concept
The pie chart shows the share of different groups in the total species diversity.
Step 2: Check the statements
Animal diversity has the largest sector, so it is the highest. The eubacteria sector is the smallest. The fungi sector is wider than the protists sector.
Step 3: Plants and animals
The plant sector is only a small fraction of the animal sector, so plant diversity is not equal to animal diversity.
Step 4: Conclusion
Statement C is the incorrect one.
Final Answer:
The incorrect statement is that plant species diversity equals animal species diversity.
\[ \boxed{\text{(C) }\text{Plant species diversity is equal to animal species diversity.}} \]