Light and electron microscopy of whole mounts prepared from water samples collected in July and August 1977 at thirteen stations in thee vicinity of Godhavn (Disko Bugt, West Greenland), has led to the enumeration of approximately 100 nanoplanktonic taxa. A full account is given of field and laboratory methods. The most conspicuous algal class was the Prymnesiophyceae with more than 38 species. Among the heterotrophic organisms listed the Choanoflagellida was the most important single group, comprising 28 species. Two new choanoflagellate taxa are described on the basis of West Greeenland material: Conion groenlandicum gen. et sp. nov. and Diaphanoeca undulata sp.nov.
In order to facilitate immediate comparison of closely related taxa Diaphanoeca sphaerica sp.nov. is described on the basis of Danish material.
Thirteen of the loricate choanoflagellate species listed are new recordings for West Greenland. A summary of previous findings of the choanoflagellate species encountered in the Disko Bugt samples show that three species (Conion groenlandicum, Pleurasiga caudata and Parvicorbicula serratula) are so far known from arctic and subarctic localities only. A pronounced vertical distribution pattern of choanoflagellate species was observed at one station southeast of Godhavn. Three distinct species associations occurred in this particular water column (0-300m).