Abstract

The morphology and infraciliature of three newly recorded Aspidisca species in Korea, two collected from the eastern coast and one collected from Jeju Island, were investigated in vivo and after protargol impregnation. The three species are as follows: A. dentata Kahl, 1928, A. hexeris Quennerstedt, 1869, and A. polystyla Stein, 1859. The three species are characterized by having a “polystyla-arrangement” of frontoventral cirri: 1) A. dentata is characterized by having a broadly rotund body shape, a distinct peristomial spur, and a dorsal thorn; 2) A. hexeris is characterized by a broadly oval body shape, four projections along the left margin of body, and the single peristomial spur; and 3) A. polystyla has the broadly rotund body shape, transverse cirri each split into several parts (especially in vivo), and lacking of the peristomial spur. Among them, A. dentata and A. polystyla are poorly known and lack morphological description based on silver staining. In the present study, we provide a brief diagnosis, remarks, and photomicrographs.