Fine structural studies on the flagellate genus Bicoeca I. - Bicoeca maris with particular emphasis on the flagellar apparatus

The colorless flagellate B. maris was studied by light microscopy (largely confirming previous studies), and by EM of whole mounts and sections. Each cell is heterokont and attached by its smooth posterior flagellum to the bottom of a hyaline lorica, which in the EM is shown to consist of fibers, not arranged in any distinct pattern. This flagellum for some distance after its emergence from the cell remains closely appressed to the cell in a longitudinal groove. The front flagellum is free and bears tripartite hairs, also found in the endoplasmic reticulum and in the perinuclear space. The nucleus is lateral and associated with the flagellar basal bodies, with the single Golgi body, and with a membrane bound structure of unknown function and origin. The mitochondria contain tubular cristae. The very complicated flagellar apparatus which includes at least 5 microtubular and 5 cross-banded structures is described in detail. Part of it is connected directly with the so-called peristome,which appears to function in food uptake. The phylogeny of Bicoeca is discussed, based on the evidence obtained from this and 2 other recent studies.