A new marine gastrotrich species of the genus Tetranchyroderma (Macrodasyida: Thaumastodermatidae) from Korea

Abstract

Surveys of marine gastrotrichs on the coast of South Korea yielded a new species of the genus Tetranchyroderma, bearing five-pronged hooks as a cuticular armature. Tetranchyroderma hummoni sp. nov. is characterized by a dorsal armature adorned with pentancres, whose central tines are about twice as long as peripheral tines. The new species is also characterized by bearing three large and broad papillae per side along boundary row of pentancres on oral hood, a pair of rod-like cephalic tentacles, and a pair of modified pestle organs. Moreover, this new species is clearly distinguished from its congeners by the number of dorsal, dorsolateral and ventrolateral cirratum-type tubes (6&#8722 10, 13&#8722 19, and 9&#8722 14 per side, respectively), and by a pair of foot-like ventral adhesive tubes. The description of the new species belonging to the genus Tetranchyroderma is based on detailed illustrations and scanning electron microscopy. We also provide a short account on the variability within the species, including the morphological difference between juveniles and adults.ned with pentancres, whose central tines are about twice as long as peripheral tines. The new species is also characterized by bearing three large and broad papillae per side along boundary row of pentancres on oral hood, a pair of rod-like cephalic tentacles, and a pair of modified pestle organs. Moreover, this new species is clearly distinguished from its congeners by the number of dorsal, dorsolateral and ventrolateral cirratum-type tubes (6&#8722 10, 13&#8722 19, and 9&#8722 14 per side, respectively), and by a pair of foot-like ventral adhesive tubes. The description of the new species belonging to the genus Tetranchyroderma is based on detailed illustrations and scanning electron microscopy. We also provide a short account on the variability within the species, including the morphological difference between juveniles and adults.