A new gastrotrich, Musellifer leasiae sp. nov. (Paucitubulatina: Muselliferidae), from Antarctica—the first Muselliferidae species description from the Southern Hemisphere

A new gastrotrich species, Musellifer leasiae sp. nov., is described from the west coast of the Antarctic Peninsula. The species is recognised by its considerable size, up to 415 m, and by its conspicuous three-lobed, keeled head scales. Besides the new species, the genus Musellifer accommodates five additional species known from the Mediterranean Sea, the Black Sea, the Central-West Atlantic, the Northeast Atlantic, and the Northeast Pacific, and from depths ranging from sublittoral to 5.485 m depth. A representative of Musellifer has previously been reported from Antarctica, but M. leasiae sp. nov. represents the first formally described Muselliferidae species from the Southern Hemisphere, and from the polar regions.