In 1850, Helen Fitch (later Helen Fitch Parker) tried to publish a description of a new species of snail by having her future Brother-in-Law present it as a paper before the American Association for the Advancement of Science. Louis Agassiz may or may not have figured it out, but he did publicly criticize Samuel Parker for not comparing the new species against all known species.
So how would you avoid the same criticism in the description of a new species of butterfly? Would you say: “I compared this butterfly against all the other butterflies I could identify?” Or would you be a little more subtle when you described your next new species 20 years later?
So they published the list in April, then they referred to the list in the description.
The complete description can be found here.