Paramecium

Paramecium O.F. Muller, 1773 (ref. ID; 2014)

From Dr. Inaki

From Dr. Inaki

From Dr. Inaki

From Dr. Inaki

Class Oligohymenophora: Subclass Hymenostomata: Order Hymenostomatida (ref. ID; 2014)
Ciliophora: Hymenostomatida (ref. ID; 7599)

Synonym Paramaecium O.F. Muller (ref. ID; 1618)

[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)

[ref. ID; 7435]
The molecular diversity within the D2 domain of the 23S ribosomal RNA molecules of Paramecium. (ref. ID; 7435)

  1. Paramecium africanum (ref. ID; 4903)
  2. Paramecium ambiguum (ref. ID; 4903)
  3. Paramecium arcticum (ref. ID; 4903)

    Paramecium aurelia-complex (ref. ID; 4061, 4062, 4063, 4064, 4611, 5910, 7704)

    [ref. ID; 4061]
    Traditional means of distinguishing different species of the genus Paramecium have been by body and nuclear morphology. The discovery of mating-type characteristics by Sonneborn, however, led to the realization that what was though to be a single species (Paramecium aurelia) was, in fact, at lest 14 genetically isolated sibling species. Sonneborn hesitated to establish separate "named" species for many years because of a lack of objective criteria for establishing mating-type groups. This difficulty was overcome in the early 1970's when isoenzyme gel migration characteristics showed correlations with such groups (which Sonneborn had termed "syngens"); this allowed the establishment of formally named taxonomic species. (ref. ID; 4061)

    [ref. ID; 4063]
    Originally, the taxon "Paramecium aurelia" was used to lump together a number of organism that were morphologically similar but between which gene flow did not always occur. As more information became available, particularly through application of biochemical techniques, classification of this group of organisms achieved finer resolution. At first, the 14 subgroups were called "varieties" on the basis of specificity of the mating types, that is, the specific selectively of the breeding relations. Subsequently the 14 varieties were designated "biological species", or "syngens", but not given species status, on the grounds that mating type identification was difficult to learn and apply to new strains and that it was undesirable to base identification on living material that had to be maintained in the laboratory and could easily be lost or mixed up. When it became possible to freeze and store paramecia in liquid nitrogen efficiently, and the syngens could be identified by simple biochemical procedures (such as starch gel electrophoresis of enzymes), species status was at last given to the 14 syngens, now considered sibling species of an "aurelia complex". (ref. ID; 4063)

    1. Paramecium primaurelia (ref. ID; 4062, 4063, 4611) = Paramecium aurelia subspecies 1 (ref. ID; 3829)
    2. Paramecium tetraurelia (ref. ID; 4062, 4063, 4611) = Paramecium aurelia syngen 4 (ref. ID; 3737, 3811)
    3. Paramecium biaurelia (ref. ID; 3987, 4062, 4063, 4611)
    4. Paramecium decaurelia (ref. ID; 4063, 4611)
    5. Paramecium dodecaurelia (ref. ID; 4062, 4063, 4611)
    6. Paramecium octaurelia (ref. ID; 3987, 4062, 4063, 4611)
    7. Paramecium novaurelia (ref. ID; 4062, 4063, 4611)
    8. Paramecium pentaurelia (ref. ID; 4062, 4063, 4611)
    9. Paramecium quadecaurelia (ref. ID; 4063, 4611)
    10. Paramecium sonneborni (ref. ID; 4061)
    11. Paramecium septaurelia (ref. ID; 4062, 4063, 4611)
    12. Paramecium sexaurelia (ref. ID; 3987, 4062, 4063, 4611)
    13. Paramecium tredecaurelia (ref. ID; 3987, 4062, 4063, 4611)
    14. Paramecium triaurelia (ref. ID; 4062, 4063, 4611)
    15. Paramecium undecaurelia (ref. ID; 4062, 4611)

    [ref. ID; 7704]
    The organism known for nearly 200 years as Paramecium aurelia was only one of several commonly recognized species of the genus. From the point of view of easily determined phenotypic characters (body size and shape, number of micronuclei, number of contractile vacuoles, presence or absence of symbitotic zoochlorellae), it was generally readily distingushiable from such other frequently encountered forms as P. caudaum, P. multimicronucleatum, and P. bursaria. Determination of these "morphological" species was possible by use of simple light microscopy, with almost any textbook as guide (e.g., Kudo 1966). The pre-1975 taxonomic history of Paramecium spp. is well documented in many places: the aging but author-itative accounts by Kalmus (1931) and Wichterman (1953) may be cited as well as the relatively recent chapter by Vivier (1974). Nearly 45 years ago, Sonneborn (1939), appreciating the abiding genetic differences he had discovered among various lines of P. aurelia, proposed labels that could be used of separate such different breeding populations. The term he suggested was "variety", and it was immediately adapted by ciliate geneticists and physiologists everywhere. Some 18 years later, keenly aware that he was dealing with "physiological" and/or "genetic", as opposed to the classical "morphological", species, Sonneborn (1957) introduced the word "syngen" to better describe what he and others had been calling varieties. Although general protozoologists were often reluctant to accept this term (excellent though it was) and some ecologists (e.g., Hairston 1958) chided the Bloomington school for not assigning at that time regular latinized names to these sibling or cryptic species, Sonneborn, with commendable caution, postponed such a significant taxonomic step (i.e., splitting up the long familiar P. aurelia into several separate species all with different names) until he felt certain that more relief than confusion would result from such an action. Then, in 1975 (though see also Sonneborn 1974), convinced that numerous characters (beyond only sexual compatibility ones) were finally available for distinguishing paramecium species and that living "reference specimens" of each were obtainable by anyone from a reliable long-term source, Sonneborn took the overdue step and published his already classic paper (Sonneborn 1975) on the "Paramecium aurelia complex of fourteen sibling species", in which he gave fully distinctive taxonomic names to each. In short, varieties of the old P. aurelia had become syngens that, in turn, now became taxonomically valid separate species. (ref. ID; 7704)

  4. Paramecium aurelia Ehrenberg, 1838 (ref. ID; 1335, 1622, 1629, 2245) or 1848 (ref. ID; 3116) reported year? (ref. ID; 1618)
    Syn; Paramecium aurelia Dujardin, 1841
  5. Paramecium aurelia Foissner et al., 1994 (ref. ID; 4488)
  6. Paramecium aurelia O.F. Muller, 1773 (ref. ID; 4611) or 1786 (ref. ID; 1622)
    See; Paramecium caudatum
  7. Paramecium aurelium Ehrenberg (ref. ID; 5624)
  8. Paramecium biaurelia (ref. ID; 3813, 3987, 4063, 4850)
    See; Paramecium aurelia-complex
  9. Paramecium bursaria (ref. ID; 191, 3292, 4903)
  10. Paramecium bursaria Ehrenberg (ref. ID; 1219, 1618) or (Ehrenberg, 1831) Focke, 1836 (ref. ID; 4611), (Ehrenberg) Focker, 1836 (ref. ID; 1335, 1622, 1629, 2245), (Ehrenberg) Focker, 1843 (ref. ID; 3116)
    Syn; Loxodes bursaria Ehrenberg, 1831 (ref. ID; 4611)
  11. Paramecium bursaria Fock, 1836 (ref. ID; 7399)
  12. Paramecium bursaria Focke (ref. ID; 3698)
  13. Paramecium calkinsi Woodruff, 1921 (ref. ID; 1335, 1622, 4611, 7399) reported year? (ref. ID; 1618) reported author and year? (ref. ID; 4903)
  14. Paramecium caudatum Ehrenberg, 1833 (ref. ID; 4488, 4611) or 1838 (ref. ID; 1219, 1622, 1629, 2245, 3116) reported year? (ref. ID; 1618, 3342, 3698, 5462) reported author and year? (ref. ID; 191, 3292, 4064, 4903)
    Syn; Paramecium aurelia O.F. Muller, 1786 (ref. ID; 1622)
  15. Paramecium chilodonides (ref. ID; 1622, 4903)
  16. Paramecium chlorelligerum (ref. ID; 1620, 4903)
  17. Paramecium chrysalis O.F. Muller, 1786
    See; Pleuronema crassum (ref. ID; 3116)
  18. Paramecium colpoda Ehrenberg, 1831
    See; Colpidium colpoda (ref. ID; 3116)
  19. Paramecium compressum Ehrenberg, 1830 (ref. ID; 4730)
  20. Paramecium compressum Ehrenberg, 1838
    See; Plagiotoma lumbrici (ref. ID; 4730)
  21. Parameiucm cucllio Quenn., 1867 (ref. ID; 3116)
    See; Plagiopyla nasuta (ref. ID; 3116)
  22. Paramecium decaurelia (ref. ID; 4063)
    See; Paramecium aurelia-complex
  23. Paramecium dodecaurelia (ref. ID; 4063)
    See; Paramecium aurelia-complex
  24. Paramecium dragescoi (ref. ID; 4903)
  25. Paramecium duboscqui Chatton & Brachon, 1933 (ref. ID; 7399 redescribed paper) reported author and year? (ref. ID; 4830, 4903)
  26. Paramecium ficarium Kahl, 1928 (ref. ID; 1622, 4903)
  27. Paramecium glaucum Claparede & Lachmann, 1858 (ref. ID; 1622)
  28. Paramecium griseolum Perty, 1852(?)
    See; Cryptochilum griseolum (ref. ID; 1622)
  29. Paramecium jankowskii (ref. ID; 4903)
  30. Paramecium jenningsi Diller & Earl, 1958 (ref. ID; 1618, 4903) reported author and year? (ref. ID; 3813, 4064)
  31. Paramecium marinum Kent, 1881 (ref. ID; 1622)
    Syn; Helicostoma oblongum Cohn, 1866 (ref. ID; 1622)

    Paramecium multimicronucleatum-complex

  32. Paramecium multimicronucleatum Powers & Mitchell, 1910 (ref. ID; 1335, 1622) reported year? (ref. ID; 1618) reported author and year? (ref. ID; 191, 3292, 3990, 4903)
  33. Paramecium nephridiatum V. Gelei, 1925 (ref. ID; 1622, 4903, 7486)
  34. Paramecium nigrum Burger, 1908
    See; Frontonia atra Ehrenberg, 1833 (ref. ID; 1622)
  35. Paramecium novaurelia (ref. ID; 4063, 4850)
    See; Paramecium aurelia-complex
  36. Paramecium octaurelia (ref. ID; 3813, 3899, 3987, 4063)
    See; Paramecium aurelia-complex (ref. ID; 3987, 4063)
  37. Paramecium pentaurelia (ref. ID; 4063)
    See; Paramecium aurelia-complex
  38. Paramecium polycaryum Woodruff, 1923 (ref. ID; 1335, 1622) reported year? (ref. ID; 1618) , Woodruff & Spencer, 1923 (ref. ID; 7399) reported author and year? (ref. ID; 191, 4903)
  39. Paramecium porculus (ref. ID; 4903)
  40. Paramecium primaurelia (ref. ID; 3813, 3829, 4063, 4760, 4850)
    See; Paramecium aurelia subspecies 1 (ref. ID; 3829, 4063)
  41. Parameicum pseudoputrinum Baumeister (ref. ID; 1219) reported author and year? (ref. ID; 4903)
  42. Paramecium putrinum Claparede & Lachmann, 1858 (ref. ID; 1622, 1629) or 1859 (ref. ID; 4611) reported year? (ref. ID; 1219, 1618) reported author and year? (ref. ID; 4903, 7599)
  43. Paramecium pyriforme Gourret & Roeser, 1886 (ref. ID; 1622)
  44. Paramecium quadecaurelia (ref. ID; 4063)
    See; Paramecium aurelia-complex
  45. Paramecium septaurelia (ref. ID; 3813, 4063)
    See; Paramecium aurelia-complex
  46. Paramecium sexaurelia (ref. ID; 3987, 4063)
    See; Paramecium aurelia-complex (ref. ID; 3987)
  47. Paramecium sonneborni Aufderheide, Daggett & Nerad, 1983 (ref. ID; 4061 original paper)
    See; Paramecium aurelia-complex
  48. Paramecium tetraurelia Sonneborn, 1975 (ref. ID; 4207) reported author and year? (ref. ID; 191, 3636, 3647, 3654, 3737, 3811, 3813, 3899, 4063, 4850, 6551, 7715, 7734, 7756)
    See; Paramecium aurelia syngen 4 (ref. ID; 3737, 3811)
  49. Paramecium traunsteineri (ref. ID; 1622)
  50. Paramecium tredecaurelia (ref. ID; 3987, 4063)
    See; Paramecium aurelia-complex (ref. ID; 3987)
  51. Paramecium triaurelia (ref. ID; 3813, 4063, 4850)
    See; Paramecium aurelia-complex (ref. ID; 4063)
  52. Paramecium trichium Stokes, 1885 (ref. ID; 1335, 1622, 2245, 7399) reported year? (ref. ID; 1219, 1618, 3342, 3698) reported author and year? (ref. ID; 191, 646, 7447)
  53. Paramecium undecaurelia (ref. ID; 4062)
    See; Paramecium aurelia-complex
  54. Paramecium woodruffi Wenrich, 1928 (ref. ID; 1335, 1618, 1622, 4611, 7399) reported author and year? (ref. ID; 4903)

Paramecium aurelia Ehrenberg, 1838 (ref. ID; 1335, 1622, 1629, 2245) or 1848 (ref. ID; 3116) reported year? (ref. ID; 1618)

Synonym

Paramecium aurelia Dujardin, 1841

Descriptions

Two small vesicular micronuclei, a massive macronucleus; two contractile vacuoles on aboral surface; posterior end more rounded that P. caudatum; in fresh water. (ref. ID; 1618)

Measurements

120-180 um long. (ref. ID; 1618)

Paramecium bursaria Ehrenberg (ref. ID; 1219, 1618) or (Ehrenberg, 1831) Focke, 1836 (ref. ID; 4611), (Ehrenberg) Focker, 1836 (ref. ID; 1335, 1622, 1629, 2245), (Ehrenberg) Focker, 1843 (ref. ID; 3116) reported author and year? (ref. ID; 3292)

Synonym

Loxodes bursaria Ehrenberg, 1831 (ref. ID; 4611)

Descriptions

Foot-shaped, more or less flattened; uniform ciliation except for a group of long caudal cilia; green with symbiotic zoochlorellae; a long broad vestibulum leads to the buccal cavity, the buccal ciliary apparatus is characterized by 2 "peniculi"; 1 compact micronucleus; 2 contractile vacuoles; numerous prominent trichocysts. (ref. ID; 1219)
Foot-shaped, somewhat compressed; green with zoochlorellae as symbionts; a compact micronucleus; a macronucleus; two contractile vacuoles; in fresh water. (ref. ID; 1618)

Measurements

Length 180-300 um. (ref. ID; 1219)
About 100-150 by 50-60 um. (ref. ID; 1618)

Paramecium calkinsi Woodruff, 1921 (ref. ID; 1335, 1622, 4611, 7399) reported year? (ref. ID; 1618)

Descriptions

Foot-shaped; posterior end broadly rounded; two vesicular micronuclei; two contractile vacuoles; in fresh, brackish and salt water. (ref. ID; 1618)

Measurements

100-150 by 50 um. (ref. ID; 1618)

Paramecium caudatum Ehrenberg, 1833 (ref. ID; 4488, 4611) or 1838 (ref. ID; 1219, 1622, 1629, 2245, 3116) reported year? (ref. ID; 1618, 3342, 3698, 5462) reported author and year? (ref. ID; 3292, 4064)

Synonym

Paramecium aurelia O.F. Muller, 1786 (ref. ID; 1622)

Descriptions

Cigar-shaped, posterior end bluntly pointed and with a group of long cilia, ciliation otherwise uniform; vestibulum long and slightly oblique; buccal cavity with one endoral membrane and 2 peniculi; 1 ellipsoid macronucleus and 1 compact micronucleus; 2 contractile vacuoles, each with radial canals, near the aboral surface, numerous trichocysts, which may discharge explosively, all over the body. (ref. ID; 1219)
With a compact micronucleus, a massive macronucleus; two contractile vacuoles on aboral surface; posterior end bluntly pointed; in fresh water. The most widely distributed species. (ref. ID; 1618)

Measurements

Length 90-150 um. (ref. ID; 1219)
180-300 um long. (ref. ID; 1618)
180-260x40-50 um. (ref. ID; 3342)

Paramecium duboscqui Chatton & Brachon, 1933 (ref. ID; 7399 redescribed paper) reported author and year? (ref. ID; 4830, 4903)

Descriptions

[ref. ID; 7399]
The body shape with its rounded posterior end and broad anterior part is of the "bursaria type" (Wichterman 1986). The oral groove is broad and oblique, and the anterior-right part of the body extends and twists to the ventral side, so that the whole body is kidney-shaped in lateral view when the animal is moderately starved. The body surface is uniformly ciliated except for the three or four long caudal cilia at the posterior end. The body length of 30 randomly chosen, fixed specimens ranged from 80 to 150 um. (ref. ID; 7399)

Remarks

Chatton and Brachon (1933) reported that they collected their strain from a sewer in Banyuls-sur-Mer in January and April in 1933. The collecting seasons and the habitats of the two strains are so similar that the phenomenon cannot be considered as accidental. The temperature of sewer water in winter and early spring in France should be at its lowest for the year. It thus seems clear that the French strain of P. duboscqui must also be adapted to lower temperatures. At least two species of Paramecium of the bursalia group, Paramecium polycaryum and Paramecium woodruffi, are rarely found, although P. polycaryum is worldwide in distribution. Paramecium duboscqui may not be a rare species at all. Its absence from collections may reflect the fact that fewer collections of protozoa are made in the wintertime. Paramecium duboscqui clearly belongs to the bursaria group based on its nearly body-shape, i.e. the truncated anterior end, the rounded posterior end, the dorso-ventral flattening, the terminal cytoproct, and the pattern of stomatogenesis (Shi 1980). Its characteristics led the authors to the conclusion that Woodruff (1921) is fully correct in his classification of the species of Paramecium into "aurelia" and "bursaria" groups. They are really two natural groups formed in the long proccess of phylogeny in Paramecium. The twist of the anterior body of P. duboscqui and its reniform outline in lateral view are unique among the species of the bursaria group. Swimming in a right spiral is a characteristic shared only by P. calkinsi. In its contractile vacuole structure, P. duboscqui resembles P. trichium, which also has vesicle-fed contractile vacuoles. These are the only species of Paramecium that lack collecting canals. Paramecium trichium also has an unusual nucleolar structure, not like that of P. duboscqui, but nucleoli "pocketed" in the surface of the macronucleus. This species is the smallest in the genus, but some strains are large enough to overlap with P. duboscqui size range. It has a subcylindrical body, a single micronucleus, and a complex mating system. The morphological and breeding differences between these two species are significant enough to separated them. The right spiral swimming of P. calkinsi is a characteristic shared by P. duboscqui, but P. calkinsi has a buccal overture below the center of the body, compared to P. duboscqui buccal overture at or above the midline. It is euryhaline and can be found in freshwater ponds as well as marine tide pools. The breeding system of P. duboscqui, one syngen and two mating types, is like those of P. polycaryum and P. woodruffi, but more collections and breeding studies of these three species may well turn up other syngens as it did in P. calkinsi. It seems unlikely, however, that the breeding systems in these species will ever approach the complexity of the breeding systems of P. bursaria and P. trichium with their many syngens and multiple mating types. (ref. ID; 7399)

Temperature restrictions

Many collections from Majia Ditch were made year round for 14 years. Winter in Harbin is from November to March, and the water temperature in the shallow water at the edge of the ditch drops below 10 degrees C. Paramecium duboscqui was collected only at these temperatures. It was collected frequently during winter, but when water temperature rose to 15 degrees C, it disappeared. Where it summers is unknown, and even in winter, it did not appear in collections from other sites. (ref. ID; 7399)

Type locality

Collected from running water in Majia Ditch, Harbin, China, the overall length of which is more than 30 km. Industrially polluted water and domestic sewage drain into its upper reaches, and it empties into the Songhua Riber in Harbin city proper. (ref. ID; 7399)

Type materials

The slides of the type-specimens and the living strains are preserved in the Laboratory of Protozoology in Harbin Normal University. (ref. ID; 7399)

Paramecium jenningsi Diller & Earl, 1958 (ref. ID; 1618) reported author and year? (ref. ID; 3813, 4064)

Descriptions

Resembles P. aurelia in general morphology; two micronuclei larger than those of P. aurelia; macronuclear anlagen with long persisting chromatinic centers. (ref. ID; 1618)

Measurements

115-218 um long. (ref. ID; 1618)

Paramecium multimicronucleatum< Powers & Mitchell, 1910 (ref. ID; 1335, 1622) reported year? (ref. ID; 1618) reported author and year? (ref. ID; 3292, 3990)

Descriptions

3-7 contractile vacuoles; four or more vesicular micronuclei; a single macronucleus; in fresh water. (ref. ID; 1618)
The somatic kinetosomes, single or double, appear as small dark granules; issuing from them is a kinetodesmal (Kd) fiber that runs anteriorly and to the right of the kinety, overlapping with more anteriorly located fibers to form a single kinetosomes are more closely spaced and the kinetodesmata are thicker by virtue of being formed by a larger number of overlapping Kd fibers. (ref. ID; 3990)

Measurements

The largest species, 200-330 um long. (ref. ID; 1618)

Paramecium nephridiatum V. Gelei, 1925 (ref. ID; 1622, 4903, 7486)

Descriptions

The cell shape with its rounded posterior end, and broad anterior part is of the "bursaria" type (Wichterman 1986) or "woodruffi" type according to Jankowski (1969). The oral opening is situated a little anterior to the middle of the cell. The cell surface is uniformly ciliated except for several long caudal cilia located close to the posterior end of the dorsal side, but not on the top. The abundant subpellicular trichocysts are distributed uniformly. Specimens were about 145x47 um long in vivo but shrank 10% after the silver nitrate impregnation. In silver-impregnated specimens, there were ~38 rows of ventral kineties and ~35 dorsal kineties. The preoral suture is distinct, but the postoral suture is very obscure. The cytoproct is situated in the posterior third. The vestibular zone is conspicuous and is terminated by the distinctive shape of the buccal opening. Two peniculi and open quadrulus are located on the dorsal and left wall of the buccal cavity. The endoral membrane is situated along the entire right edge of the buccal opening but its dikinetids are not recognizable in all specimens. It has 15 dikinetids on the average. The buccal cavity size various around 30 um. On the dorsal side of the body the contractile vacuole pores are very distinctive both on impregnated specimens as well as in living cells. Usually, both contractile vacuoles have more than one pore each, typically two or three. However, we have found two stocks (WCh-1 and WS-12) where one of the contractile vacuoles quite often (up to 50%) had only one pore. Both contractile vacuoles usually have 8-14 collecting canals, ten on average. Numerous crystals were very often found in the cytoplasm, but their quantity and location varied, probably depending on the culture conditions. During cell division, the anterior daughter cell (proter) more closely resembled the maternal cell than the opisthe which, at first, looks highly similar to some other peniculines. The nuclear apparatus is located in the anterior part of the cell. One slightly ellipsoid or ovoid macronucleus, ~30x36 um in living cell and ~17x23 um in stained cells, on average, resides just anterior to the equator of the cell. In Feulgen-stained cells the macronucleus has a very intense colour. The three to four spherical micronuclei of the "endosomal" type (Fokin 1997), ~3 um in diam. (on average) are distributed irregularly along the anterior part of cell. Endocytobiotic bacteria are often found in the cytoplasm (Fokin 1989) and can also be found in the perinuclear space and in the macronucleus (Fokin 1989; Fokin and Sabaneyeva 1997). The species is characterized by a binary mating type system. Using more than 20 stocks from different localities, two unambiguous mating types have been detected. The old macronucleus fragments before the separation of the conjugants. The new macronuclear anlagen are four in number. Selfing in stock cultures takes place on rare occasions. (ref. ID; 7486)

Swimming behavior

During swimming this species spirals on its long axis in both directions (Fokin 1987). We could no find any simple triggers (food, time) for changing this swimming direction. Typically, "left spiral swimmers" and "right spiral swimmers" were present at the same time in the culture. During the several years of investigation of this trait there was some preference of the cells from the same stocks to spiral in the left direction. (ref. ID; 7486)

Remarks

Gelei (1925) described a new species of Paramecium, Paramecium nephridiatum, based on the material which he had found in his laboratory aquarium. This population was in fact a mixture of the new species and Paramecium caudatum (Gelei 1938). This was the reason why some features of the new ciliate were similar to P. caudatum so that no one recognized this new species in nature, though reference to P. nephridiatum was made by Kahl (1931) and Kalmus (1931). Gelei (1938) redescribed the species from a native population (Tisza River, Szeged, Hungary) using a "clean culture". For unknown reasons, this new description did not attract the attention of protozoologists and in all subsequent reviews, P. nephridiatum was considered a nonvalid species (Vivier 1974; Wichterman 1953, 1986) even when the article of Gelei (1938) was listed in the references. Only once was P. nephridiatum mentioned in a short abstract as a species living in Florida, USA (Bovee 1983), although characters of the species were not listed in this publication. Since 1983, one of us (S. F) has repeatedly collected a species of Paramecium with multiple contactile vacuole pores, which is a distinctive trait of P. nephridiatum, although it was considered for a time as a feature of Paramecium woodruffi (Agamaliev 1983; Fokin 1986), Jankowski (pers. commun.). (ref. ID; 7486)

Occurrence and ecology

A number of stocks of P. nephridiatum were isolated from the sea shores of northern Europe: the North, Baltic, White, and Barents Sea coasts. It was detected during sampling in Woods Hole, MA, USA, Atlantic Ocean and on Sakhalin Island, Sea of Okhotsk. The salinity of these samples varied from 1.5-32 0/00. The species was also found in a fresh-water body in Jerusalem Zoo, Israel. Samples were taken mainly during the summer, from mid-April (Wood Hole) to November (North Sea coast). Sampling of the same wild population of P. nephridiatum (Sredny Island, White Sea, Russia) has been repeated every year since 1990 to observe long-time changes in the population, as well as the euryhaline ability of the species. This population, as well as the euryhaline abiliy of the species. This population was present at salinities from 4-35 0/00 and in the temperature range from 10-25 degrees C. Very often the populations of P. nephridiatum occurred at the lower limit of oxgen concentrations. They were mainly feeding on bacteria. In the same samples these other ciliates were usually found: Prorodon sp., Frontonia marina, Metopus sp., P. calkinsi, P. woodruffi, and sometimes P. duboscqui. (ref. ID; 7486)

Paramecium polycaryum Woodruff, 1923 (ref. ID; 1335, 1622) reported year? (ref. ID; 1618), Woodruff & Spencer, 1923 (ref. ID; 7399) reported author and year? (ref. ID; 191, 4903)

Descriptions

Form similar to P. bursaria; two contractile vacuoles; 3-8 vesicular micronuclei; in fresh water. (ref. ID; 1618)

Measurements

70-110 um long. (ref. ID; 1618)

Paramecium putrinum Claparede & Lachmann, 1858 (ref. ID; 1622, 1629) or 1859 (ref. ID; 4611) reported year? (ref. ID; 1219, 1618) reported author and year? (ref. ID; 4903, 7599)

Descriptions

Similar to P. bursaria but without zoochlorellae; macronucleus elongated, kidney-shaped; 1 micronucleus; only 1 contractile vacuole; no trichocysts (Lepsi, 1926; Kahl, 1930) Records of P. putrinum are scanty, and it is in fact doubtful whether the species is valid. This problem is of some saprobiological interest since Liebmann (1962) classified P. putrinum as a polysaprobic indicator organism. On the other hand, Sramek-Husek (1954) failed to find any specimens of P. putrinum during his saprobiological studies in Czehoslovakia; all representatives of the genus Paramecium that he found in the more heavily polluted zones were referable to P. trichium. Therefore, Sramek-Husek submitted that the polysaprobic "P. putrinum" of earlier authors is really P. trichium Stokes. P. putrinum sensu Liebmann has 2 contractile vacuoles, both shown with radial canals; P. putrinum sensu Liebmann was recorded from the sludge of polluted reservoirs, dammed rivers, lakes etc., in the upper zone of trickling filters, sewage drains, and in floating tufts of Sphaerotilus. Taxonomic studies of "P. putrinum" and P. trichium are thus urgently required. (ref. ID; 1219)
Similar to P. bursaria, but a single contractile vacuole and an elongated macronucleus; no zoochlorellae; in fresh water. (ref. ID; 1618)
The ultrastructural study of postoral microtubules. (ref. ID; 7599)

Measurements

About 130 um long (ref. ID; 1219)
80-150 um long. (ref. ID; 1618)

Paramecium sonneborni Aufderheide, Daggett & Nerad, 1983 (ref. ID; 4061 original paper)

See

Paramecium aurelia-complex

Descriptions

[ref. ID; 4061]
  • Body morphology: The shape of the cell body from a cloned population of organisms grown at maximum rate at 27 degrees C is typical for that of the P. aurelia complex with the exception that the posterior end of most cells is pointed, bearing a superficial resemblance to Paramecium caudatum. Two contractile vacuole are present. (ref. ID; 4061)
  • Nuclear morphology: One macronucleus is present, ca. 70 um long, showing the prolate spheroid shape characteristic of all species of Paramecium. In interphase cells, the macronucleus is ventral and anterior to the oral apparatus, as is also usual with paramecia. Two vesicular micronuclei are consistently present. Many micronuclei show a concentric arrangement of the chromatin, while others have chromatin dispersed in a coarse reticulum. Twenty micronuclei examined in 12 living cells, using phase-contrast optics, have a mean diameter of 4.9 um (+/-0.18 SE), with a range of 3.5-6.7 um. (ref. ID; 4061)
  • Sexual behavior: Both conjugation and autogamy have been observed, and two macronuclear anlagen are seen after fertilization. Two mating types have been identified. Mating-type determination appears to be karyonidal, although cytoplasmic determination has not been completely ruled out. Mating-reactive cells of this organism will not react with mating-reactive cells of any of the other 14 species assignable to the aurelia complex. These is no apparent diurnal cycle. (ref. ID; 4061)
  • Further remarks: The life expectancy of clones of our new species is relatively long compared to other species in the aurelia complex. Clones are viable for at least 250 generations. No endosymbionts have been detected in the species. (ref. ID; 4061)

    Etymology

    The new species has been named Paramecium sonneborni n. sp. in honor of the late Dr. Tracy M. Sonneborn of Indiana University. (ref. ID; 4061)

    Type locality

    College Station, Texas (Lat. 30 degrees 37'55''N, Long. 96 degrees 18'15''W). (ref. ID; 4061)

    Type-specimens

    Holotype and paratype slides (Nos. USNM31926 and 31927) have been deposited in the Ciliate Type Slide Collection, Smithsonian Institution, Washington, D.C. Paratype specimens remain in the collection of the senior author. (ref. ID; 4061)

    Type culture

    Paramecium sonneborni stock TAMU:0580:1 ATCC 30995) (ref. ID; 4061)

    Measurements

    Maximum body length of 26 fixed, silver-impregnated specimens ranged from 130 to 186 um, with a mean length of 154.4 um (+/-2.9 SE). Maximum body width of the 26 cells ranged from 39 to 64 um, with a mean width of 50.3 um (+/-1.3 SE). (ref. ID; 4061)

    Paramecium tetraurelia Sonneborn, 1975 (ref. ID; 4207) reported author and year? (ref. ID; 191, 3636, 3647, 3654, 3737, 3811, 3813, 3899, 4063, 4850, 6551, 7715, 7734, 7756)

    See

    Paramecium aurelia syngen 4 (ref. ID; 3737, 3811)

    Descriptions

    Parallel study of stomatogenic and micronuclear activities in sexual reproduction. (ref. ID; 7715)

    Paramecium trichium Stokes, 1885 (ref. ID; 1335, 1622, 2245, 7399) reported year? (ref. ID; 1219, 1618, 3342, 3698) reported author and year? (ref. ID; 191, 646, 7447)

    Descriptions

    Body shape highly variable, more or less ellipsoid, somewhat flattened; ciliation uniform except for a group of long caudal cilia; vestibulum and buccal equipment similar to those of P. bursaria; 1 macronucleus; 1 compact micronucleus; 2 contractile vacuole, each with a convoluted outlet; unlike other members of its genus, P. trichium has a contractile vacuole without radial canals but with tributary vacuoles; numerous trichocysts all over the body; posterior part of the body more or less filled with dark granules. According to Sramek-Husek (1954), P. pseudoputrinum Baumeister is referable to P. trichium. (ref. ID; 1219)
    Oblong, somewhat compressed; a compact micronucleus; two contractile vacuoles deeply situated, each with a convoluted outlet; in fresh water. (ref. ID; 1618)

    [ref. ID; 7447]

    Examined material

    Clone 4B-1 (mating type IV) of the ciliate Paramecium trichium. This clone, which was esatblihsed in January 1991, is one of the F1 progeny of a crossbetween stocks OM4(IV) and MMB(III), which were kinely provided by Dr. Toshikazu Kosaka, Hirosima University. The clone 4B-1 was sexually mature and did not show any sign of senility during the course of this work. (ref. ID; 7447)

    Measurements

    Length 50-120 um. (ref. ID; 1219)
    50-105 (80-90) um long. (ref. ID; 1618)
    80-110x45-60 um. (ref. ID; 3342)

    Paramecium woodruffi Wenrich, 1928 (ref. ID; 1335, 1618, 1622, 4611, 7399) reported author and year? (ref. ID; 4903)

    Descriptions

    Similar to P. polycaryum; two contractile vacuoles; 3-4 vesicular micronuclei; brackish water. (ref. ID; 1618)

    Measurements

    150-210 um long. (ref. ID; 1618)