Kentrophoros (Ciliophora, Karyorelictea) has Oral Vestiges: a Reinvestigation of K. fistulosus (FaurÉ-Fremiet, 1950) Using Protargol Impregnation

Abstract

Summary The morphology, infraciliature, and epibiontic bacteria community of Kentrophoros fistulosus ( FraurE-Fremiet , 1950) were studied in live cells, in protargol impregnated specimens, and with the scanning electron microscope. Kentrophoros fistulosus is involuted tube-like, except for the body ends; the right side bears many longitudinal ciliary rows, the involuted left side is sparsely ciliated and covered with few, thin spirilla and countless rod-shaped sulphur bacteria which are phagocytised through the cell surface. Thus, Kentrophoros has been considered to be secondarily mouthless. The infraciliature consists of dikinetids throughout. The anterior dikinetids of the right side are specialized, i.e. more closely spaced and have both basal bodies ciliated, oblique axes, and nematodesmata-like fibres forming a basket-like structure. These specializations are considered to be vestiges of an oral infraciliature. The posterior end also has specialized dikinetids which give rise to a tuft of caudal cilia whose basal bodies are associated with conspicuous fibres extending into the tail. The left side seemingly has two ciliary rows extending along the cell margins. However, detailed analysis showed that these rows are very likely a single kinety curving around the cell. The bacterial lawn is embedded in a thick layer of mucus, produced by the ciliate to keep the symbiotic kitchen garden in place. The data emphasize the loxodid relationship of Kenfrophoros , earlier proposed by Kahl and Raikov , and suggest synonymizing K. longissimus ( Dragesco ) and K. tubiformis ( Raikov & Kovaleva ) with K. fistulosus ( FaurE-Fremiet . Improved diagnoses are provided for the family Kentrophoridae Jankowski and the genus Kentrophoros Sauerbrey . The nomenclature of Kentrophoros is revised, i.e. correct names, dates, and authorships are given for all species described.