[ref. ID; 2014]
Medium- to large sized ciliate (120-300 um long), ovoid, elongate, foot- or cigar-shaped. The anterior end may be rounded or obliquely truncated and the posterior rounded or conical. The shape is rather asymmetrical due to the presence of an oblique depression, the oral groove, running from the apex of the cell to about the middle of the body on the ventral surface. The oral aperture is located at the posterior end of the oral groove. While the oral groove is prominent and easily seen the aperture is rarely visible without staining the cell with silver. Inside the buccal cavity there is a comparatively small undulating membrane on the right and 2 membranelles called peniculi lying alongside each other. Membranelle M3 comprise four rows of kinetosomes which diverge centrally to form a structure known as a quadrulus. Somatic ciliation is complete and uniform with 1, 2 or 3 hexagonal units. There are both pre- and post-oral sutures and trichocysts present. 1 to many (commonly 2) contractile vacuoles present which may be served by radiating canals. Cytoproct on the ventral surface located sub-orally. Macronucleus ovoid to reniform in shape, usually centrally located with variable number of micronuclei close by. Locomotion characteristically vigorous and spiralling anticlockwise.
Wenrich (1928). The species of Paramecium are still in a state of flux. The classical species P. aurelia has recently been subdivided into 14 sibling species by Sonneborn (1975) and Gates, Powelson and Berger (1974) and Gates and Berger (1976) have discussed the morphological separation of these species. Vivier (1974) also reviews the classically named species.
Quote; Colin R. Curds, Michael A. Gates and David McL. Roberts "British and other freshwater ciliated protozoa Part II Ciliophora: Oligohymenophora and Polyhymenophora" Cambridge University Press, 1983 (ref. ID; 2014)
Paramecium primaurelia (ref. ID; 4062, 4063, 4611) = Paramecium aurelia subspecies 1 (ref. ID; 3829)
Paramecium tetraurelia (ref. ID; 4062, 4063, 4611) = Paramecium aurelia syngen 4 (ref. ID; 3737, 3811)
Paramecium biaurelia (ref. ID; 3987, 4062, 4063, 4611)
Paramecium decaurelia (ref. ID; 4063, 4611)
Paramecium dodecaurelia (ref. ID; 4062, 4063, 4611)
Paramecium octaurelia (ref. ID; 3987, 4062, 4063, 4611)
Paramecium novaurelia (ref. ID; 4062, 4063, 4611)
Paramecium pentaurelia (ref. ID; 4062, 4063, 4611)
Paramecium quadecaurelia (ref. ID; 4063, 4611)
Paramecium sonneborni (ref. ID; 4061)
Paramecium septaurelia (ref. ID; 4062, 4063, 4611)
Paramecium sexaurelia (ref. ID; 3987, 4062, 4063, 4611)
Paramecium tredecaurelia (ref. ID; 3987, 4062, 4063, 4611)
Paramecium triaurelia (ref. ID; 4062, 4063, 4611)
Paramecium undecaurelia (ref. ID; 4062, 4611)