A new Tetranchyroderma (Gastrotricha, Thaumastodermatidae) with triancres from the Mediterranean Sea.

As part of a project dealing with the meiofauna diversity of three Italian Marine Protected Areas (MPA), a new species of gastrotrich is described. Tetranchyrodermn aapton n. sp. is characterized by the cuticular armature made up of triancres whose shape approaches those of T.tribulosumcrathercthanctheancresof T. adeleaeorT.gausancrum the only other congeners exhibiting a triancrous covering. The new species is from the MPA Capo Caccia-Isola Piana (Northwestern Sardinia, Italy) where it was found in organogenous sediment collected at 20 m water depth,together with 17 other gastrotrich species, most of which appear undescribed. The results call for widening thesurvey to deeper sediments, usually neglected in gastrotrich faunistic surveys.