Description of a new species of Bursatella Blainville, 1817 (Gastropoda, Aplysiida, Aplysiidae) from southern Australia

Currently, the sea hare genus Bursatella contains two species, the circumglobal B. leachii and the recently re-erected B. ocelligera which is restricted to the central Pacific. Among circumglobally-distributed aplysiid species there is often considerable intraspecific morphological variation. This diminishes the reliability of using only morphology for species delimitation. In these cases, the inclusion of molecular data as part of an integrated taxonomic approach is particularly useful. Although Australian Bursatella have a near circum-continental distribution, animals from the western and southern coasts exhibit a distinct morphology that warrants investigation as to whether or not they represent a separate taxon. Specimens of B. leachii and the putatively novel taxon were used in an integrated taxonomic study with delimitation based on a consensus protocol. Combined molecular and morphological data supported the presence of a separate species, Bursatella hirsuta n. sp., which is described herein. Although adult animals may be readily distinguished from other sea hares by their overall appearance, juveniles may be mistaken for unstriped forms of the small sea hare Stylocheilus striatus.