“Lissarca miliaris” (Bivalvia: Philobryidae): a species able to cross the Antarctic Convergence or a species complex?

Abstract

The philobryid bivalve Lissarca miliaris (Philippi 1845) has been regarded as widespread in sub-Antarctic and Antarctic waters, being able to overcome the environmental discontinuity imposed by the Antarctic Convergence. This contribution searches to re-evaluate if such distributional range is true or an artifact, originated from a misunderstanding of the original concept of that species. For that, topotypic specimens of L. miliaris and additional material from the Scotia Arc islands, the Antarctic Peninsula and Kerguelen Island, historically assigned to that species are studied. Based on morphological, anatomical, biological and molecular characters, a pair of geminate species is recognized: L. miliaris occurring north of the Antarctic Convergence, in the sub-Antarctic waters of the Magellan Region, and L. bennetti Preston (1916) occurring south of the Antarctic Convergence, at the Scotia Arc islands and the Antarctic Peninsula. The latter is a name here revalidated after more than 70 years of disuse. Both L. miliaris and L. bennetti are fully redescribed and properly figured, and a neotype for the former is designated. The information reunited in this study reveals that the diversification of the genus Lissarca in sub-Antarctic and Antarctic waters is greater than previously thought.