Well don't I just feel embarrassed...
I obviously knew there were tons of species of worms, but I didn't know there were so many species of the nightcrawler earthworm...
I got this trivia from a National Geographic article I read a couple years ago, so my memory was apparently a little foggy.
Anyway, the point the article was trying to make was that the pilgrims introduced the common night crawler to hardwood forests of New England and the Upper Midwest that had no native earth worms. Certain species of plants relied on plant debris that littered the floor with no earthworms to break it down...and then they came along and blah blah blah...
Here's the link to the article if anyone is interested:
America, Found and Lost - National Geographic - May 2007
Thanks for the info, Ramon!!!