Fig. 4

Sexually mature P. leidyi. a Sexual individual (DIC imaging). b Asexual individual from the same culture as a. c The same sexual individual as in a, imaged using darkfield, showing the gametes (appearing white, indicated by asterisks) within the body. d–e Sperm and oocytes, respectively, dissected from the worm. f Same image as a, but with sexual structures outlined and labeled. The marked structures were identified based on the anatomy of sexual naidids and other clitellates as described in [21, 65]. Scale bars 200 µm (a–c); 50 µm (d, e)