Prostoma mixtum, Timofeeva, 1912

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

4. Prostoma mixtum

(Annex Fig. 1D)

Description. Body length from 10 to 25 mm, width up to 0.7 mm. Body slightly thickened in middle, rounded. Head slightly separated from remaining body. Body colour yellowish, with pink or brown tint. Dark brown cephalic patch present behind anterior pair eyes, often covering the latter; bright white spot (sometimes divided into two) of cephalic gland present in front of cephalic patch. Behind cephalic patch, transversely accumulated glands of white strip present, from which white glandular strip extends posteriorly, stretching across entire dorsum of animal, reaching anal gland.

Locality. Sublittoral silt at 16–18 m depth (Annex Fig. 2 , II, III, IV, V). Darse, muddy silt, 5 m deep (Annex Fig. 2 , VI).

Remarks. The original figure (рис. 4) shows two accessory stylet pouches, each containing two to four accessory stylets; now Tetrastemma mixtum ( 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.