Prostoma bistriatum, Timofeev, 1911

Kajihara, Hiroshi, 2025, A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping?, Zootaxa 5646 (4), pp. 451-500 : 486

3. Prostoma bistriatum

(Annex Fig. 1C)

Description. Very small nemertean, approximately 6 mm long and 0.5 mm wide. Body white with yellowish tint. Two dark-brown stripes running dorsally, separated by wide area darker than rest of body, in middle of which narrow, shiny-white strip of glandular cells stretches. Dark-brown half-ring present behind posterior pair of eyes, from which aforementioned two dorsal stripes extend. Cephalic gland in form of white spot between eyes. At posterior end of body, white anal gland also present.

Locality. Two specimens, sublittoral silt at 16–18 m depth (Annex Fig. 2 , III, dredging number 44) .

Remarks. The original figure (рис. 3) shows two accessory stylet pouches, each containing two and three accessory stylets; now Tetrastemma bipeltatum ( Timofeev, 1911) .

Figures

FIGURE 2. Prostoma clepsinoides Dugès, 1828 from Lake Biwa, Japan. A, Entire specimen in living state, lost after photographed. B, C, Transverse sections through proboscis anterior chamber; white arrowheads pointing to proboscis nerves. D, Sagittal section through the opening of the oesophagus–rhynchodaeum complex; black arrowheads pointing to cilia on ventral wall of oesophagus; anterior to the left. E, Magnification of D, showing sparse cilia on ventral wall of oesophagus, indicated by black arrowheads. F, Magnification of D; black arrowhead pointing to longitudinal muscle fibre along rhynchodaeum.G, Sagittal section near rhynchodaeal opening; anterior to the right. B, D, E, F, ICHUM 6272; C, ICHUM 6277; G, ICHUM 6273.