A very short, functionally constrained sequence diagnoses cone snails in several Conasprella clades

► A short (338 bp) nuclear conserved intron sequence (CIS) of the γ-glutamyl carboxylase gene defines a cone snail phylogeny. ► Counterintuitively, longer mtDNA sequences (12SrRNA and COI) are less phylogenetically informative than the CIS. ► Formerly considered cogeneric with Conus (Conidae), the conasprellans are clearly distinct from other Conus species. ► Repeated success with short intron 9 sequences indicates its utility for resolving neogastropod phylogenies in general.