Paramecium

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

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   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)
   • Taxonomic-nomenclatural consequences: Although Sonneborn's decision was laudable and offered neither surprise nor difficulty to co-workers in ciliate genetics, it is still having far-reaching effects on the thousands of other biologists around the world who, on occasion, work with or have to deal with species of Paramecium. The list of such persons includes teachers, all levels of students, textbook writers, review authors, and editors, as well as ecologists, evolutionary biologists, taxonomists, hydrobiologists, cytologists, cell physiologists, and biochemists. Since the essentially irreversible consequences of Sonneborn's action affect many biologists, though some may be quite unaware of this fact, what he actually did warrants further clarification and discussion.
     • Names of the new species involved. Currently, there are 14 "sibling species" comprising the Paramecium aurelia complex (shortenable to the "aurelia complex" when it is clear that these paramecia are the topic). These are valid taxonomic species, and their names were both wisely and ingeniously based on the numerical sequence used -with rare exception (see Sonneborn 1975)- in the older designations of variety and syngen. The new names follow; the authorship and date of each is the same, viz., "Sonneborn, 1975": Paramecium primaurelia, P. biaurelia, P. triaurelia, P. tetraurelia, P. pentaurelia, P. sexaurelia, P. septaurelia, P. octaurelia, P. novaurelia, P. decaurelia, P. undecaurelia, P. dodecaurelia, P. tredecaurelia, and P. quadecaurelia. These are the specific names for former syngnes numbers 1-14. Over the years, most intensively studied of these species in genetic research has been P. tetraurelia (i.e., old variety, later syngen 4). (ref. ID; 7704)
     • What happened to P. aurelia itself?. A major problem that confronted Sonneborn for some 30 years, as he contemplated separating the several species of "P. aurelia", was what to do with the original single taxonomic name. He was urged by many to retain it: certainly textbook writers and general biologists would have appreciated having that time-revered and so widely used a name preserved (it is found in titles of books, e.g., see Beale, 1954, and Jurand & Selman, 1969, as well as in hundreds of papers). But, in brief, the dilemma he faced was this: If one syngen (e.g., number 1 or number 4) was deliberately chosen to be the one-and only P. aurelia, then how or what could the remaining sibling species be named? The judicious idea of using the sequential-numerical latinized prefixes listed above would have to go, since a "hole" would be caused by removal of either 1 or 4. Furthermore, and this is supported by provisions of the Internationl Code of Zoological Nomenclature (see Corliss 1963) how can anyone known exactly which syngen O.F. Muller was looking at two centuries ago, when he used the specific epithet "aurelia" for this ciliate? So, Sonneborn (1975) declared "P. aurelia" to be an unusable specific name, not attachable with certainty to an organism identical with O.F. Muller's ciliate, thus truly a nomen dubium. In effect, then, P. aurelia, as a valid taxonomic name, has disappeared. Because of overlapping in morphological features, general descriptions of all 14 new species essentially fit the older characterizations of the single P. aurelia. For this reason, we urge that the term "P. aurelia complex" be used in the general literature of the future as the best single replacement of the original, now on-existent, species. Today, specialists can, and should when appropriate, go a step further and state their papers, when they know it to be true, that species P. primaurelia and P. tetraurelia (or whatever) of this complex were the specific organisms investigated in their particular study. (ref. ID; 7704)
   • Characteristics used to separate species: Before 1970, syngen (now species) separation depended almost entirely on breeding tests, demonstration of the failure to obtain gene flow between any two groups that would result in viable (and lasting) populations of offspring. Thus, proper identification depended on having standardized living cultures ("tester" stocks) available for the tests and on possessing the requisite technical knowledge to handle the organisms in a precise and controlled manner (Sonneborn 1950, 1970). College teachers and field ecologists were not usually expected to go to such trouble for their routine requirements in identification: "Paramecium aurelia" adequately met their needs. Now, the situation has changed. Presumptive identification of all species can be routinely carried out without recourse to standard living cultures, thankns principally to the availability of techniques for enzyme analyses (Adams and Allen 1975; Allen 1967; Allen and Gibson 1975). Newer morphological information, including recognition of specific endosymbionts, and data on zoogeographical distribution have also contributed characteristics usable by biologists in distinguishing unambiguously at least some of the species comprising the aurelia complex. Finally, purebred stocks (generally kept cryopreserved), serving as standard or reference strain material, are now conveniently available to anyone who may wish to fully match collections from the wild with pedigreed known material. (ref. ID; 7704)
     • Isozyme patterns. Under standardizedd conditions, the isozymes of an enzyme for a given organism may present a consistent distribution pattern (a zymogram) if the enzyme is electrophoresed through a starch gel. Since the expression of isozymes is a phenotypic expression of the genotype of an organism, enzymes can be studied geneticists like any other expressed heritable trait. Beginning in the late 1960's and continuing into the '70's, S.L. Allen and other investigated enzymes of paramecia now assigned to the aurelia complex (Admas and Allen 1975; Allen et al. 1971, Allen et al. 1973; Allen and Gibson 1971, 1975; Byrne and Cronkite 1971; Tait 1970, 1978). One result of many of these studies was the demonstration that esterase zymograms could be used to recognize differences among all of the species except two, P. primaurelia and P. pentaurelia. More recently, using the same approach as Allen and her colleagues for 172 bacterized strains of the aurelia complex, it has been shown to be possible to distinguish all species (including P. primaurelia and P. pentaurelia) on the basis of esterase zymograms. (ref. ID; 7704)
     • Morphological features. Unfortunately, considering the great need of field ecologists and hydrobiologist for "quick-and-easy" cytological approaches to species identifications, the anatomical attributes of most of the species of the aurelia complex general do not provide data instantly usable in their certain taxonomic separation. In breif, nearly all of these 14 recently erected Paramecium species reveal features -after appliciation of some method of silver impregnation, for example- that neatly key them out to be simply members of the old Paramecium aurelia! This is of no help at all, of course. And as experienced field person can generally distinguish between species of the aurelia complex and other species of the genus using living material alone, without need of fixing, staining, etc. Nevertheless, careful analyses of light-microscopically visible morphological characters by multivariant biometrical methods have proven useful in some cases (e.g., see Gates and Berger 1976; Gates et al. 1975; Powelson et al. 1975). Morphogenetic features have yet to be explored in depth in the serice of taxonomy for the aurelia complex species, but their value in the higher-level systematics and phylogeny of ciliates is well established (Corliss 1968, 1979). Life cycle features, even cell size (in some cases), may be helpful to an extent; but a thorough knowledge of one's culture (this alone requires laboratory, not field, observations), employment of standard conditions, etc. would be required before the data could be used comparatively with a high degree of reliability. Ultrastructural information, so important in comparative ciliatology at higher taxonomic levels, is of practically no value at the subgeneric levels, for Paramecium or any other forms, because of its relative evolutionary conservativeness. (ref. ID; 7704)
     • Ecological and biogeographical characteristics. There is inferential evidence (Sonneborn 1975) that certain of the 14 sibling species of the aurelia complex are limited to, or have preference for, restricted areas of the world (to give a negative example, strains of neither P. novaurelia nor P. quadecaurelia have been found to date in the United States). Yet few regions of the globe have been extensively sampled, so apparent distributional differences may not turn out to be true. On the other hand, the old belief that protist species, in general, are ubiquitous and thus have cosmopolitan ditributions is quite possibly not the case. However, our present knowledge is still too limited to draw a conclusion, one way or the other. "Morphological" species often appear to be found in very widely separated places; but, as in the case of Paramecium itself, such forms may sometimes be shown to be quite different genetically. Microhabitat. Differences have been little studied from a comparative point of view. Physiological adaptations in relation to species variability have also seldom been investigated in members of the aurelia complex. (ref. ID; 7704)
       Other features of possible use. A variety of other physiological and "life cycle" or behavioral characters, raging from fission rate to temperature tolerance, might profitably be explored for use in separation of species of the aurelia complex. To date, such data are scarce and are generally considered unworthy of pursuit, since electrophoretic techniques are so reliable and relatively simple to carry out under standard laboratory conditions. Karyotypic and other (DNA, chromosome number etc.) nuclear characters, though little studied in extenso, seem to show as much or more variation within one of these species as between them. Mating reaction, mating type inheritance, etc., are, in the broadest sense, part of the "breeding relations" or genetics of these organisms and thus are valuable for purposes of species identification. However, their utilization comparatively, as menthioned above, requires living cultures of multiple strains testable under controlled conditions, a situation that rarely obtains for a general biologist. The use of intracellular symbionts (which we elect to call "xenosomes", using the name first applied by Soldo and Godoy, 1973, to similar bodies in certain marine scuticociliates), themselves now precisely indentifiable (Preer et al. 1974; Soldo 1974), remains an intriguing possibility for separation of members of the aurelia complex. But some stocks appear to carry no xenosomes; others need to be studied more intensively for their possible endosymbionts; and still others overlap in the kinds of microorganisms they carry. (ref. ID; 7704)
   • Availability of strains (stocks): There are two major culture collections that maintain a variety of protozoan and algal species, the American Type Culture Collection (Rockville, Maryland) and the Culture Centre of Alage and Protozoa (Cambridge, England). The primary mission of both of these organization is to carefully maintain and make publicly available standardized or reference strains of these protists. Both collections maintain strains, also known as stocks, of species of the aurelia complex. The ATCC maintains all of its paramecium stocks as cryopreserved preparations, to insure long-term availability without change. A major portion of Sonneborn's collection was acquired by ATCC during the late 1970's, including "tester" stocks for all of the species. These are over 175 stocks at the ATCC now, an in the near future there will be more than 200 available. The number of paramecium strains maintained by the CCAP is not as extensive as at the ATCC, but there are some available there that are not obtainable from the ATCC. (ref. ID; 7704)
   • Proposed preactical solutions: There are some practical considerations to be kept in mind in the designation of organisms belonging to the aurelia complex. It is of paramount importance that appropriate levels of identification be used if later comparison of data is to be possible. (ref. ID; 7704)
     • For field biologists. The workers who are most likely to be faced with a practical problem of identification are field biologists. It is not possible (or at least with rare exception) to identify individual species of the aurelia complex solely on the basis of morphology. Although, as noted above, it is possible to make presumptive identifications using esterase zymograms, it is generally unlikely that most field biologists would be in a position to undertaken such an effort. However, it is now incorrect to use the specific disignation "Paramecium aurelia O.F.M, 1773" in their lists, tables, charts, etc. If the ecologist, limnologist, hydrobiolgist, plankton sampler (or whoever) is unable to do a detailed identification, then designation of the ciliate as "Paramecium sp." or as a "member of the P. aurelia complex" (perhaps using both with the second as a footnote to the first) is appropriate and ought to be employed. Such long-time authoritative field guides and textbooks as Kahl (1931) and Kudo (1966: and earlier editions), and now Bick (1972), Curds (1969), Dragesco (1970), Jahn et al. (1979) and others, are simply of no help in identification of these newly established (Sonneborn 1975) cryptic species of Paramecium. (ref. ID; 7704)
     • For laboratory experimentalists. There is no excuse, in the case of laboratory workers, not to accurately identify the organism used in their researches. Without such presice identification of strains studied, the resulting data are almost usefuless. Reference stocks, the equivalent of reagent-grade chemicals (to which such careful attention is routinely paid), are readily available, as mentioned above. If a strain other than a reference stock is used, it is possible, in almost any modern laboratory, properly identify that organism to species-level, preferably by the enzyme analyses described earlier. (ref. ID 7704)
     • For writers, teachers, and editors. The continued use of a legally discarded taxonomic name (in this case, Paramecium aurelia) by textbook writers, college professors and other teachers, and editors of journals is a disservice to science. Such carelessness perpetuates misinformation, and hence false biological information is continuously being presented as true to the entire scientific community. Such neglect of facts, wherther inavertent or otherwise, ignores important conclusions reached, often, only after years of research by competent investigators. Editors, the last to see a manuscript before it appears in print, bear a major responsibility with respect to the accuracy of a taxonomic name, the source of an experimental organism, and the precise strain or stock designations employed by an author. (ref. ID; 7704)
   • Concluding remarks on the P. aurelia problem: There is no longer a species in the genus Paramecium named P. aurelia. Ciliates that appear to be the "old" species known by that name are probably assignable to the aurelia complex of sibling species. Appropriate breeding test and/or electrophoretic studies of their enzyme systems must be carried out to determine whether or not unknown strains or new isolates belong to one of the 14 cryptic or sibling (syngenic) species recognized by Sonneborn (1975) or represent a new species in this aurelia complex. Authenticated stocks are available as cryopreserved material, and it is advisable to use only such strains in experimental laboratory work if the resulting reseach data are to be meaningful. The population of "Paramecium aurelia" found in field work can be labeled only as "Paramecium sp." unless/until proper methods of precise identification have been carried out on them. An attractive possible alternative, using a "supraspecies" name (in effect, as a substitute for the words "a member of the aurelia complex"), is discussed in our Addendum. (ref. ID; 7704)
   • Addendum: We are greatful to the Redacteur for permitting us to append a short section here concerning an excellent point brought to our attention by one of the reviewers of our manuscript, discussion of which however, would be difficult to incorporate directly to the pages of any preceeding sections. In effect, an alernative practical solution has been suggested for the problem of what name to use in identification of some sibling (jumelle) or syngenic species when sophisticated breeding or molecular techniques are not avaiable to the investgator (e.g., a field ecologist). The very recently proposed taxonomic-nomenclatural category of "supraspecies" -well described by its originators Genermont and Lamotte (1980), who acknowledge their indebtedness to nomenclaturist G. Bernardi- nicely links together taxonomically any group of species difficult to separate, one from the other, morphologically or ecologically. The term is not to be confused with the restrictive, little used, quite different category of "superspecies" (see Mayr 1969). Thus, instead of listing a population of organisms as "Paramecium sp." or "Tetrahymena sp.", indicating total ignorance of the precise (sibling) specific name to use and seemingly leaving only the genus as the first level of their identification, one could write: "Paramecium suprasp. aurelia" or "Tetrahymena suprasp. pyriformis". Usage of such terminology would clearly provide the reader with a "morphological type", as it were, but at an infrageneric (even infrasubgeneric) level. When/if the specific name is known, the new category could still be employed: for example, a biochemist might be working with Tetrahymena (suprasp. pyriformis) thermophila. In a way, the supraspecific category would replace the longer expressions "pyriformis complex" or "member of the pyriformis complex", the non-taxonomic notations recommended in a preceding section of this paper to field biologists, to be used as footnotes (in lists, tables, etc.) to the name Tetrahymena sp. One of the advantages of the idea is that it releases the term "complex" for informal usage at a still lower group level. Recall that Williams and Buhse (1983) have suggested that among the micronucleated members of the "T. pyriformis complex" one can recognize three well defined groups: the T. americanis complex, the T. borealis complex, and the T. thermophila complex. There appear to be very few disadvantages to this proposed practical solution, that is, using the supraspecies concept described above. Yet one, naturally, is that its very newness will, at first, make it unfamiliar and therefore possibly a little confusing to many readers. Also, the closeness of the spelling of the two words "supraspecies" and "superspecies" is unfortunate. From a taxonomic-nomenclatural point of view, however, we endorse with enthusiasm its future consideration by protologists. With respect to its usage with the two groups of ciliate sibling species under discussion in the present paper, only new serious problem arises. I is caused by the necessity (see Genermont and Lamotte 1980) of having a "nominate" species within each supraspecies; or, to put it another way, the Latin name of the supraspecies must be identical to the name of one (presumably the oldest) species included in the group. This causes no trouble in the case of Tetrahymena. T. (suprasp. pyriformis) pyriformis works very well. But for Paramecium, as discussed on earlier pages, there is no longer any taxonomic species P. aurelia and thus, legalistically, there can, at the moment, be no P. (suprasp. aurelia) aurelia! In their paper, our good French colleagues suggest rejection of Sonneborn's first binomen, P. primaurelia, replacing it with "P. aurelia", which would then allow a taxonomic-nomenclatural treatment parallel to that given for Tetrahymena above. But the matter cannot be handled so simply. Further discussion of this particular knotty and complex problem, however, is beyond the scope of the present paper. Its final proper resolution would involve, at the least, a carefully prepared lengthly pertition to the Intenational Commission on Zoological Nomenclature for future formal consideration by the commissioners. Unfortunately, at the present time, this restrict our giving complete support to the otherwsie attactive "alternative practical solution" discribed in this Addendum. (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

    • Paramecium multimicronucleatum syngen 1 (ref. ID; 3813, 4064)
    • Paramecium multimicronucleatum syngen 2 (ref. ID; 3813, 4064)
    • Paramecium multimicronucleatum syngen 3 (ref. ID; 3813, 4064)
    • Paramecium multimicronucleatum syngen 4 (ref. ID; 3813, 4064)
    • Paramecium multimicronucleatum syngen 5 (ref. ID; 3813, 4064)

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

Descriptions

Measurements

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

Descriptions

Measurements

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

Descriptions

Measurements

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

Descriptions

Measurements

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

Descriptions

• Argentophilic structures: In silver-impregnated specimens, the pellicular pattern forms hexagons over most of the body surface. Rhomboids are restricted to the left side of the preoral suture, and quadrilaterals are restricted to both sides of the postoral suture and the right side of the preoral suture. The preoral suture, an argyrophilic line, forms a bow-shaped curve to the organisms left. The cytoproct occupies the posterior half of the postoral suture. Two contractile vacuole pores, one for each contractile vacuole, are visible on the dorsal surface. (ref. ID; 7399)
• Buccal apparatus: The vestibulum is shallow and ends in the middle or a little above the middle of the body at the buccal overture. The endoral membrane lies along the entire right edge of the buccal overture, but from its origin to its middle, the endoral dikinetids are zig-zag or single file. From the middle to the end, the kinetosomes of the dikinetids are side by side. The anarchic field is clearly visible at the right of the posterior end of the endoral membrane. Two peniculi lie on the left wall of the buccal cavity; each contains four rows of kinetosomes. The posterior end of the dorsal peniculus does not turn to the ventral and right side although that of the quadrules does. (ref. ID; 7399)
• Stomatogenesis: During cell fission, as in other species of Paramecium, the buccal pouch for the future opisthe originates from the anarchic field and the inner portion of the right wall of the vestibulum. Three nascent membranelles extend out of the vestibulum and lie on the somatic pellicle at the right of the postoral suture. After the new buccal cavity separates from the old, the two buccal apparatuses are juxtaposed. This stomatogenesis strongly resembles that of P. bursaria (Shi 1980). (ref. ID; 7399)
• Nuclear morphology: One ellipsoid macronucleus is present just above the center of the cell. In protargol-stained interphase cells, the nucleoli in the macronucleus often aggregates into a coarse network. This network is identified as nucleolar because it stains as nucleoli do in other ciliate species not as microtubules or other supporting structures do. The number of micronuclei range from zero to six, but two micronuclei are usual. Of 1,000 cells from 10 stocks examined, 685 (68%) had two micronuclei. Micronuclei in interphase are vesicular and shaped like long spindles (ca. 5.1 um x 1.2 um in hematoxylin preparations and ca. 10.2 um x 3.2 um in protargol preparations. (ref. ID; 7399)
• Mating types: By mixing evey two combinations among 46 stocks collected from the same place, only two mating types have so far been detected. They are designated as syngen 1 in this species. This is the first report of conjugation in this species. Whether there were other mating types and syngens in collections from other locations remain to be studied. (ref. ID; 7399)
• Trichocysts: The subpellicular trichocysts are perpendicular to the surface and appear more conspicuous than in other species. In protargol preparations, the main body of the trichocyst is rather thick, and its width is nearly equal to one half of its length. The length of the tip is about two-fifths that of the main body. (ref. ID; 7399)
• Contractile vacuoles: Both contractile vacuoles are vesicle-fed. Immediately after systole the vesicles expand. At diastole, fibrils supporting the walls of the contractile vacuole are visible in the living ciliate. Probably these correspond to the tracts of microtubules that spiral around the wall of the contractile vacuole in other species of Paramecium. (ref. ID; 7399)
• Swimming behavior: In contrast to all other species of Paramecium except P. calkinsi, this ciliate characteristically spirals to the right on its long axis (clockwise) when swimming. There are two spiraling modes in swimming, and extremely narrow spiral at greatest speeds and a long spiral at average speeds. These figures indicate that the forward progress of P. duboscqui when it is swimming fastest may be slower than its forward progress when it is swimming at slower speeds. (ref. ID; 7399)

Remarks

Temperature restrictions

Type locality

Type materials

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

Descriptions

Measurements

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

Descriptions

Measurements

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

Descriptions

Swimming behavior

Remarks

Occurrence and ecology

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

Measurements

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

Measurements

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

See

Descriptions