in vivo; left side
Portrait (left side) of the odontostome ciliate, Pelodinium reniforme (Lauterborn,1908). The genus is monospecific. The cell outline is broadly reniform and laterally compressed. The right surface is slightly convex. The clear rigid pellicle bears inconspicuous longitudinal ribs. A small midline posterior indentation is bordered by 6 short blunt spines (3 each on the right and left surfaces). The cytostome and adoral zone of membranelles are located on the mid-portion of the ventral surface (not seen in this view). There is a prominent sharp tooth-like spine anterior to the cytostome. The frontal zone of kineties (5 single and 2 double rows) wraps from the left surface around the ventrum and onto the right surface to the midline. The somatic ciliature is reduced to 4 right and 3 left longitudinal kineties some of which extend at least ½ the body length. The ovoid macronucleus may be single or bipartite. There is a single posterior contractile vacuole near the cytostome. There are symbiotic methanogenic bacteria in the cytoplasm. Brownish refractile granules are clustered anteriorly. Collected from hypoxic sediment of standing freshwater near Boise, Idaho February 2004. DIC optics.
This image was taken by William Bourland. He now uses a Zeiss Axioskop 2 with Spot Insight and Spot Flex CCD cameras (Diagnostic Instruments). Image copyright: William Bourland, image used under license to MBL (micro*scope).
download as pdf file
From the collection
Freshwater and Terrestrial Microbes of Idaho (USA) and Elsewhere
|Description of Pelodinium reniforme: Ciliate, 40-50 x 30-45 microns. Shape ellipsoid to lens-shaped, laterally strongly flattened. Ventral side usually straight and with rib and projections. Dorsal side semicircular, smooth. Posterior end broadly rounded, with 2 roundish recesses, which are surrounded by 6 inconspicuous spines. Macronucleus usually two. Contractile vacuole below the adoral membranelle zone, i.e. ventral in the posterior end. Body rigidly. Pellicula shining and transparent, usually clearly serrated. On the left side three rows (1/2 to 2/3 body length). Rear range of the right side with three ciliary rows (1/3 body length). Cilia long. At the front end a "frontal ciliary band", which begins on the left side and pulls crosswise over the ventral surface up to the median of the right side; to the rear the furrows prominent from this band gather on the usually rounded off spine, which is set in by 2 typical ear-form recesses. Adoral membranelle zone in a pit in the centre of the ventral side, seen only with difficulty in living cells, consists of 12-15 membranes. What seem to be endosymbiotic bacteria occur in the cytoplasm. |