The microanatomy ofHymenomonas lacunasp.nov. (Haptophyceae)

A new species ofHymenomonasStein,Hymenomonas lacunasp.nov. from San Juan Island, Washington, U.S.A. is described using light and electron microscope techniques. The cells normally occur in non-motile clumps growing on the sides of the culture vessel. Each cell has a body covering composed of a single layer of coccoliths of unusual construction and several layers of circular unmineralized rimless scales. Occasional small elliptical scales are sometimes found. The general cytology of the cells is discussed with special attention paid to the unusual pyrenoid and the role of the Golgi body in scale and coccolith production. The relationship of this species toH. roseolaStein is discussed.