Authors: H. Visser & H.H. Veldhuijzen van Zanten
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Scientific name:

Nemertea

Vernacular name:

Snoerwormen, Ribbon Worms; Proboscis Worms, Nemertiens, Schnurwürmer, Nemertini


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family Gordiidae - Haarwormen (Gordiidae)
family Gordiidae - Gordian Knot Worms (Gordiidae)
family Gordiidae - Saitenwürmer (Gordiidae)
class Trematoda - Flukes
class Trematoda - Trématodes
class Trematoda - Saugwürmer

(Ribbon or Proboscis Worms)

Under natural conditions only one family, Tetrastemmatidae, of freshwater nemerteans is found in Europe. A representative belonging to the family Lineidae was taken from tropical aquaria in Düsseldorf, Germany.

Description
Family Tetrastemmatidae
(but05f1, descriptive picture) Predominantly marine family with only one genus, Prostoma , which is exclusively freshwater in habitat. Members of this genus are difficult to distinguish using external features only. These highly contractile worms may reach a length of 10-20(-40) mm, while the cylindrical body has a diametre of 1-4 mm. Mouth and proboscis pore are usually united into a common aperture, which is situated in front of the brain. The small cerebral organs, characteristically for Prostoma , possess glandular caps. The head usually with six eyes with a maximum of eight; juveniles with four eyes, and one (ground water) species (P. puteale , from France, Germany and Switzerland) is eyeless. The epidermis is ciliated and contains numerous mucus-secreting glands. The body wall musculature consists of an outer circular and an inner longitudinal layer. The rhynchocoel, containing the proboscis, is nearly as long as the body. The proboscis is armed with a single main stylet, with several others in reserve. The gut usually with shallow, unbranched lateral diverticula.
Prostoma is hermaphroditic, the ovotestes are in two lateral rows, alternating with the intestinal diverticula. Adults usually are reddish-brown to orange, juveniles usually paler to whitish.
Family Lineidae
Mouth and proboscis pore separate; mouth ventral, a good millimetre behind front of head; proboscis not armed. Head with horizontal cephalic slits, eyes and frontal organ absent, cephalic glands well developed. Up to 120 mm long; strikingly red with white dots.

Ecology
Family Tetrastemmatidae
These ribbon worms are rarely encountered, but locally abundant in ponds, shallow margins of lakes, or slow flowing rivers. They hunt for small annelid worms and other invertebrates, moving about through sediments, debris, masses of filamentous algae or on aquatic plants.
Family Lineidae
The worm lives inside a tube, constructed of grains of sand kitted together, in amongst the rootsystem of a plant.

Taxonomy
Family Tetrastemmatidae
Genus: Prostoma Dugès, 1828.
Gerlach (in Illies, 1978a) lists 5 species of limited distribution, but notes that distribution data are doubtful since worms attributed to this genus were reported from a larger area.
The most widely distributed "European" species P. graecensis was also found in North America, Africa, Australia, and New Zealand; P. eilhardi from Amsterdam has also been found on several sites in South America and Africa (Gibson and Moore, 1976).
Family Lineidae
Genus: Apatronemertes Wilfert and Gibson, 1974.
Species: A. albimaculosa Wilfert and Gibson, 1974.

Distribution
Family Tetrastemmatidae
The genus Prostoma was reported from most of continental Europe, including Great Britain and Ireland.
Family Lineidae
This species was found clinging to the roots of a single shipment of the aquarium-plant Vallisneria torta , delivered to a pet-shop in Düsseldorf. Wilfert and Gibson (1974) were unable to trace the presumably subtropical or tropical origin of this worm.

(after Pennak, 1953; Wilfert and Gibson, 1974; Gibson, 1982; Schwank and Bartsch, 1990; De Pauw and Vannevel, 1991; Fitter and Manuel, 1995)

phylum Nemertea
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