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However , intermediate depths of divergence in the ambystomatid species tree remain unresolved , potentially highlighting a region of rapid species radiation or a hard polytomy , and which limits our ability to comment on previous morphologically - based taxonomic groups .
 None
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities:  
Answer:
 None