4 4Università degli Studi Milano Bicocca, Dipartimento di Biotecnologie e Bioscienze, ZooPlantLab, Università di Milano Bicocca, Piazza della Scienza 2, 20126 Milano, Italy
5 5Muséum National d'Histoire Naturelle, USM 307, Ecologie et Gestion de la Biodiversité, et UMR 7205 CNRS, Origine, Structure et Evolution de la Biodiversité, 61 rue Buffon, CP 52 75231, Paris cedex 05, France
A new species of the nematode taxon Diplogastridae is described on morphology and additional molecular data. The new species cannot be grouped in any of the currently accepted diplogastrid genera. Therefore, we introduce the new genus Cutidiplogaster n. gen. along with the description of our new species Cutidiplogaster manati n. gen., n. sp. Cutidiplogaster manati n. gen., n. sp. was isolated from skin lesions of manatees, Trichechus manatus manatus, kept in Okinawa Churaumi Aquarium, Japan. The specimens were found anchored with their extraordinarily long tails to the small, thick epidermal bumps within thread algae that form part of the epizoic community on the manatee skin. Cutidiplogaster manati n. gen., n. sp. is characterised by the tube-shaped and finely annulated postdental part of the stegostom that makes it distinct from all other Diplogastridae so far known, and the coiled long tail that makes it unique in comparison with all known diplogastrids. On the basis of detail in stoma morphology in C. manati n. gen., n. sp., we discuss implications in homologising diplogastrid mouthparts and their evolution.