Crossword clue: the black rattlesnake (crotalus, or caudisona, tergemina), found in the mississippi valley.
1 answer found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).
Possible answers
pygmy rattlesnake found in moist areas from the Great Lakes to Mexico; feeds on mice and small amphibians