In a 2012 phylogenetic analysis based on mitochondrial and nuclear DNA , the plain maskray and the Ningaloo maskray ( N. ningalooensis ) were found to be the most basal members of Neotrygon . The divergence of the N. annotata lineage was estimated to have occurred ~ 54 Ma . Furthermore , the individuals sequenced in the study sorted into two genetically distinct clades , suggesting that N. annotata is a cryptic species complex . The two putative species were estimated to have diverged ~ 4 @.@ 9 Ma ; the precipitating event was likely the splitting of the ancestral population by coastline changes .