Plain Maskray - Taxonomy and Phylogeny

Taxonomy and Phylogeny

The first scientific description of the plain maskray was authored by Commonwealth Scientific and Industrial Research Organisation (CSIRO) researcher Peter Last in a 1987 issue of Memoirs of the National Museum of Victoria. The specific name annotatus comes from the Latin an ("not") and notatus ("marked"), and refers to the ray's coloration. The holotype is a male 21.2 cm (8.3 in) across, caught off Western Australia; several paratypes were also designated. Last tentatively placed the species in the genus Dasyatis, noting that it belonged to the "maskray" species group that also included the bluespotted stingray (then Dasyatis kuhlii). In 2008, Last and William White elevated the kuhlii group to the rank of full genus as Neotrygon, on the basis of morphological and molecular phylogenetic evidence.

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.