language and dna

From: Mate Kapovic
Message: 48360
Date: 2007-04-23

I read somewhere that they discovered a language in which there were 23 (or something like that) different names for 23 different species of butterflies (?) which were identical on first sight but proved different by DNA analysis. The problem is I forgot the exact details.
Does anybody have a reference and/or details about this case (or something similar)?
 
Mate