IDAE

Set to 2 different clues across 2 published puzzles, most often “Family name suffix in taxonomy” — The New York Times, Thursday, 25 December 2008.

4 letters

Every clue on record, most used first

Family name suffix in taxonomyonce
The New York Times — Thursday, 25 December 2008
Zoological name suffixonce
The New York Times — Friday, 26 April 1996