sperm bristles present
Macrostomum appendiculatum Fig 7-8.jpg

Macrostomum virginianum Fig 2-4.jpg

The stilette is curved and obliquely truncated on its convex side. This conical tube is bent at a right angle near its proximal end. p. 27
Macrostomum bulbostylum Fig 32-35.jpg

Macrostomum appendiculatum Fig 1-5.jpg

Macrostomum glochistylum Fig 13-19.jpg

The small reniform eyes are not embedded in the tissues of the ganglia. The penis-stilette is a long, curved funnel which extends from a widened proximal base to end in a slightly bent obliquely truncated terminus. The stilette termination is distinctly provided with a thin lip which projects slightly beyond the opening proper. p. 195 The sperm cell in this form is a spindler-shaped structure which is much shorter than usual for Macrostomum. Chromatin granules are present in the anterior region of the cell, while posteriorly directed setae are absent. p. 196
Macrostomum phillipsi Fig 13-16.jpg

Macrostomum lewisi Fig 1-4.jpg

The sperm cell is a thin filament with a small knobbed head containing granules. Setae are lacking in this cell. It is this present author's opinion that Okugawa has depicted an immature sperm cell. p. 205
Macrostomum reynoldsi Fig 21-25.jpg

Macrostomum ruebushi var shenandoahensis Fig 27-30.jpg

Macrostomum ruebushi var truncatum Fig 31-34.jpg

The penis-stilette is a funnel with a crenate base which is slightly obliquely truncated. The curved and pointed termination has a small distal lip. The opening is terminal. p. 45