Hi Kurt,
I don't know what the longest molluscan name is, but Phasianotrochus
irisodontes and Pseudostomatella decolorata each have 26 letters, just to
give folks something to shoot for.
Now, if you included echinoderms, the green sea urchin of our Atlantic coast
- Strongylocentrotus droehbachiensis - would win for sure at 33 letters.
That's practically an abbreviation though, compared to the crustacean name
just given by Tom!
Paul M.