Stenostomum leucops (Dugès, 1828) O. Schmidt, 1848

(Fig. 5 F–G, 7 I –J)

Localities. Loc. 1, 6, 10, 11, 16, 17, 18, 29, 31, 32, 33.

Known distribution. Cosmopolitan (in Noreña et al. 2005)

Material. Several individuals studied alive.

Description and remarks. Specimens were identified mainly based on the shape of the refractile organs (fig. 7J). A few specimens, which were collected in October had developed reproductive organs (cf. Luther 1960). In these specimens the male genital pore, which is situated dorsally at approximately 1/5, could be observed. A simple testis, is present next to the pharynx. A few specimens also contained eggs situated in between the intestine and the body wall. These sexually-mature specimens are approximately 1–2 mm, whereas the length of specimens collected in May to September ranges between 0.4 and 1 mm.