Fig. 9

Micrographs of reproductive structures of field-collected Macrostomum pellitum. Brackets denote accessions of deposited specimens, with MTP LS 2600 being the HOLOTYPE. a Ripe testis (MTP LS 2737). b Shell glands surrounding the vagina (MTP LS 2600). c The stylet with the parts of the vesicula granulorum extending into its base (MTP LS 2600). d Female antrum with the ciliated first chamber in the lower right and the thickened second chamber in the upper left. The second chamber is filled with sperm, and the connection between the chambers is indicated (arrow, MTP LS 2600). e Ripe ovary (MTP LS 2737). f Female antrum, showing an empty first chamber (left) and the second chamber (right) filled with sperm, sperm feelers of several sperm are embedded in the antrum wall (arrow, MTP LS 2617). g Composite image of a sperm, showing the short sperm bristles and the terminal brush (MTP LS 2740). h An egg during the first mitosis (note the two nuclei, arrow) in the antrum, surrounded by sperm (open arrow, MTP LS 2733). i Overview of the male system with stylet, vesicula granulorum, and both seminal vesicles (MTP LS 2600). Scale bars indicate 20 μm