Surveys of marine gastrotrichs on the coast of South Korea yielded a new species of the genus Tetranchyroderma , bearing 5-pronged hooks as a cuticular armature. Tetranchyroderma hummoni 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 3 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 (6−10, 13−19, and 9−14 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.

Two species of parasitic copepods are described from the common cloacal cavity of the algal-bearing (photosymbiotic) compound ascidian, Didemnum molle (Herdman), occurring in Okinawa, Japan. They are a new form of Lichomolgidae (Poecilostomatoida), Lobomolgus okinawaensis new genus, new species, and a new species of Notodelphyidae (Cyclopoida), Doroixys capillosus . The new genus Lobomolgus is unique among the lichomolgid genera in having in the female a pair of long, dorsolateral processes on each of the last two somites of the metasome. It is also characteristic in having in the female a highly reduced endopod (a small lobe tipped with one seta) on leg 4 and bearing an armature of III, 5 (not II,I,5) on the last exopodal segment of leg 4. Doroixys capillosus , new species, can be distinguished from its congeners by the possession of: 1) a 6-segmented antennule, 2) a mandibular endopod with 5 setae, 3) a maxilliped tipped with 6 setae, 4) a 2-segmented endopod on leg 3, and 5) a cephalosome with rounded posterolateral corners (due to the lack of processes).