Description of a new species of Patiriella from New Zealand, and review of Patiriella regularis (Echinodermata, Asteroidea) based on morphological and molecular data

Molecular and morphological analyses of Patiriella regularis revealed two distinct forms that co-occur widely around New Zealand. Morphotypes are easily diagnosed by plate arrangement along ray crests. Early last century Mortensen (1925) recorded two varieties that he considered distinct from P. regularis. Variety "a" corresponds to a form that is not P. regularis and variety "b" corresponds to juvenile forms of P. regularis. Mitochondrial DNA data are congruent with morphology, and indicate that the forms are genetically highly distinct from each other (21.1-23.0% sequence divergence) and from other representatives of Patiriella (17.6-24.5%). Despite their sympatry and morphological similarity, phylogenetic analysis suggests that the two forms represent a paraphyletic assemblage. We therefore describe a new littoral species from New Zealand: Patiriella mortenseni sp. nov. (Mortensen's variety "a"). Our morphological revision also encompasses similar asterinids recorded from the region: Asterina novaezelandiae, Patiriella oliveri, and Patiriella mimica (junior synonym of P. regularis).