Tubifex nerthus Michaelsen 1908

Worldwide the number of records are few and it appears to be a phantom species. There are no known records from The Netherlands and only one historical record from a pond in Belgium (Tétry 1940). For some reason Verdonschot (2007) reported it from The Netherlands, but we were unable to trace this record. Recorded by Michaelsen (1908, 1909), and Ude (1929) from Rügen, Northern Germany, Krieg (2006) reported it from from the Elbe estuary and Schöll & Balzer (1998) from the upper reaches of the Elbe. This latter Elbe material unfortunately got lost (pers. comm. F. Schöll, 2011). Hagen (1951) reported it from Schleswig-Holstein in Aalbeek (between Hemmelsdorfer See and the Baltic Sea), river Trave near the Teerhof Isle and in the Kieler Förde near Stein. Furthermore, it has been reported from Turkey (Balik et al. 2001, Yildiz & Balik 2005), North America (Kathman & Brinkhurst 1998, Stimpson et al. 1982), Britain (Silverburn, Isle of Man; Brinkhurst 1971), Finland (Laakso 1969), Sweden (as Tubifex insignis (Eisen); Michaelsen 1908), (former eastern) Germany, Denmark, Czech Republic (Ploucnice) (Hrabe 1981), and Israel (Martinez-Ansemil & Giani 1987). The report on the presence in Italy, seems to be a mistake (pers. comm. of G.Bonomi to B.Sambugar).

This species has been described by Michaelsen (1908) from Rügen (Mecklenburg-Vorpommern, Germany) from poorly preserved specimens. Michaelsen (1908) had material that was poorly preserved and dirty, and was not able to give a good description of the distal end of the dorsal chaeta. His drawings have subsequently been copied by Ude (1929), Chekanovskaya (1962) and Wilcke (1967). A British specimen was drawn by Brinkhurst (1971) and subsequently copied by Brinkhurst & Jamieson (1971). Finally the specimen described and figured in Hrabe (1981) are mostly original drawings except for the penial chaetae, which are copied from Michaelsen (1908). Hrabe (1981) described material from the Czech republic (Ploucnice) which is different from the original account (Michaelsen 1908), from the British (Brinkhurst 1971), and the North American material (Kathman & Brinkhurst 1998). As this description does not fit the original account, it is likely that this specimen concerns (an aberrant specimen of) another species. Brinkhurst & Baker (1979) suggest that the peculiar penial chaetae in European material are merely chaetae with the tip broken off. Wilcke (1967) probably made a mistake when reporting on a modified penial chaetae in X.