Description of a new species of Paraplehnia (Polycladida, Stylochoidea) from Japan, with inference on the phylogenetic position of Plehniidae

We describe a new species of polyclad flatworm, Paraplehniaseisuiae sp. nov. , from 298–310 m depths in the Sea of Kumano, West Pacific, Japan. Paraplehniaseisuiae sp. nov. is characterized by i) a developed muscular wall proximally occupying about one-third of the prostatic vesicle, ii) no common duct between the spermiducal bulbs and the prostatic vesicle, and iii) a genital pit between the male and female gonopores. We provide a partial...