Notes on Microturbellaria from freshwater habitats in the Netherlands

INTRODUCTION Freshwater microturbellaria of the Netherlands were studied already by De Man (1874). Since then this subject has not received much attention and much faunistic research remains to be done on this large and interesting group. The present paper deals with material from distribution mains for drinking water in the South and the West of the Netherlands and from a canal in the city of Leiden. A new species of Microdalyellia is described. MATERIAL AND METHODS The material was taken from the following samples: Sample no. 150. Leiden, Zoeterwoudse Singel (canal), near Koepoortsbrug. Between vegetation (Glyceria); decaying vegetable debris, mainly Glyceria and Aesculus leaves; 10-15 cm deep; temperature above 50 C (there was no ice in the second half of January). 20 January 1965. Leg. J. van der Land. Sample no. 151. Same locality. 0-10 cm deep (waterlevel had fallen); temperature 4.5-5·5° C (no ice). 12 February 1965. Sample no. 152. Same locality. 0-10 cm deep; temperature 30 C (whole canal covered with ice). 3 March 1965. Sample no. 155. Same locality. 10-15 cm deep; temperature abt. 17o C; material strongly decomposing. 10 May 1965. Sample no. 159. Zundert (province of Noord-Brabant) ; distribution mains for drinking water. Detritus sieved with plankton net from water taken from fire hydrant. 1 December 1964. Sample received from Waterleidingmaatschappij West Noord-Brabant. Sample no. 161. Hillegom (province of Zuid-Holland). Same biotope. 14 January 1965. Leg. J. C. van der Vlugt.