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

[Display omitted] ► A short (338bp) 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. The traditional taxonomy of ca. 700 cone snails assigns all species to a single genus, Conus Linnaeus 1758. However, an increasing body of evidence suggests that some belong to a phylogenetically distinct clade that is sometimes referred to as Conasprella. Previous work (Kraus et al., 2011) showed that a short (259bp) conserved intronic sequence (CIS) of the γ-glutamyl carboxylase gene (intron 9) can be used to delineate deep phylogenetic relationships among some groups of Conus. The work described here uses intron 9 (338bp) to resolve problematic relationships among the conasprellans and to distinguish them from Conus proper. Synapomorphic mutations at just 39 sites can resolve several groups within Conasprella because the informative region of intron 9 is so well conserved that the phylogenetic signal is not obscured by homoplasies at conflicting sites. Intron 9 also unambiguously distinguishes Conasprella as a whole from Conus because the conserved regions that are so well conserved within each group are not alignable and clearly not homologous between them. This pattern suggests that expression of the γ-glutamyl carboxylase gene may have undergone a functionally significant change in Conus or Conasprella shortly after they diverged.