hellbender vs hellbender salamander

hellbender

noun
  • A giant salamander (genus Cryptobranchus) of North America that inhabits large, swiftly flowing streams with rocky bottoms. 

  • A reckless, headstrong person. 

hellbender salamander

How often have the words hellbender and hellbender salamander occurred in a corpus of books? (source: Google Ngram Viewer )