Pteridomonas (ter-rid-owe-moan-ass) a colourless pedinellid (stramenopile) flagellate. Like other pedinellids, it has a single apical flagellum surrounded by a wreath of fine arms, and usually attached to the substrate by a fine stalk. The stalk is contractile and may also release from the substrate. The flagellum beats with an undulating beat pattern. Phase contrast.