They forgot M (monadine)
http://www.icfpcontest.org/Endo.pdf
Endo is an alien life form, belonging to the species of the Fuun. Endo needs your help! Earth’s environmental conditions can be harsh for a life form not properly adapted. Endo had the bad luck of being dropped on Earth by an Interstellar Garbage Collector. Both the life form and its faithful space ship Arrow were severely hurt in the crash, and even worse, after leaving the damaged space craft Endo was hit by a cargo container that was also dropped by the Garbage Collector.
…
Fuun DNA can be represented as a finite sequence consisting of four bases, denoted by the four letters I (infinine), C (continuine), F (functorine), and P (polymorphine).
The puns, they just won’t stop.