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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Uronema

Uronema Dujardin, 1841 (ref. ID; 2014)

From Dr. Inaki

From Dr. Inaki

Class Oligohymenophora: Subclass Hymenostomata: Order Scuticociliatida (ref. ID; 2014)
Class Oligohymenophora de Puytorac et al., 1974: Order Scuticociliatida Small, 1967 (ref. ID; 4893)
Subclass Scuticociliatia (ref. ID; 7213)

[ref. ID; 2014]
Small (about 30 um long), elongate ovoid ciliate with a slight anterior constriction that often disappears on silver preparations. Somewhat laterally flattened. Inconspicuous oral aperture located equatorially to slightly anteriorly. A small undulating membrane and 3 small internal membranelles. Somatic ciliation in 15-16 kineties and there is a caudal cilium. Anterior pole unciliated. Kinetosomes usually paired and gathered into the anterior right corner of a rectangular argentophilic network except in one species. Single contractile vacuole in posterior body half. Trichocysts present. Macronucleus in anterior body half but not apical. A large number of species have been described and there is much disagreement on which are valid.
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)
  1. Uronema acutum V. Buddenbrock, 1920 (ref. ID; 1622, 4524)
  2. Uronema castellonensis Fernandez-Leborans & Zaldumbide, 1984 (ref. ID; 4679 original paper)
  3. Uronema digitiformis Cuenot, 1891
    See; Philasterides digitiformis (ref. ID; 1622)
  4. Uronema elegans Maupas, 1883 (ref. ID; 1622, 2085, 4524) reported author and year? (ref. ID; 7213)
  5. Uronema filificum Kahl, 1931 (ref. ID; 645, 1622, 2085, 4523, 4524) reported year? (ref. ID; 3846)
  6. Uronema granulatum Lepsi, 1926 (ref. ID; 1622)
  7. Uronema marina (Kahl) (ref. ID; 1308) or Dujardin (ref. ID; 2117, 5624)
  8. Uronema marina Moebius, 1888
    See; Cohnilembus pusillus Quennerstedt, 1869 (ref. ID; 1622)
  9. Uronema marinum Dujardin, 1841 (ref. ID; 1622, 1896, 2085, 2245, 2316, 3119, 3593, 4524, 4893) reported year? (ref. ID; 1219, 1618, 3771) reported author and year? (ref. ID; 191, 4611, 7536)
    Syn; Loxocephalus putrinus Kahl, 1926 (ref. ID; 1621)
  10. Uronema microcrepis Penard, 1922
    See; Dexiotrichides centralis (ref. ID; 1622)
  11. Uronema nigricans (O.F. Muller, 1786) (ref. ID; 4524), (O.F. Muller, 1786) Florentin, 1901 (ref. ID; 645, 4488, 4611) or Florentin, 1901 (ref. ID; 1629, 2085) reported author and year? (ref. ID; 191, 3954)
    Syn; Cyclidium nigricans O.F. Muller, 1786 (ref. ID; 4611); Uronema parduczi Foissner, 1971 (ref. ID; 4611)
  12. Uronema parduczi Foissner, 1971 (ref. ID; 2085, 4524) reported author and year? (ref. ID; 191)
    See; Uronema nigricans (ref. ID; 4611)
  13. Uronema pluricaudatum (Norland, 1937) (ref. ID; 1308, 1335, 1618, 2085)
  14. Uronema rabaudi Cepede (ref. ID; 1622)
  15. Uronema schewiakoffi V. Buddenbrock, 1920
    Syn; Uronema marina Schewiakoff, 1889 (ref. ID; 1622)
  16. Uronema sociale Penard, 1922
    See; Platynematum sociale (ref. ID; 4611)

Uronema castellonensis Fernandez-Leborans & Zaldumbide, 1984 (ref. ID; 4679 original paper)

Diagnosis

Marine ciliata. Oval-shaped body of 28.2-37.8x18-25.8 um. Thirteen somatic kineties. Oval macronucleus, in the front half of the ciliate with 13.2-14.4x9.6-12.6 um. Spherical micronucleus. The oral area, with a length of 10.2-12.6 um is made up a paroral formation (PF) and three membranelles (M1, M2 and M3). The PF is composed of 2 rows of kinetosomes; M1 has only one row of kinetosomes, M2 has 3 rows and M3 also has 3 rows. A fibril system is located above the oral area. (ref. ID; 4679)

Descriptions

The specimens of this species have a more or less oval shape, with a round posterior end and a pointed anterior end. The organism is from 28.2-37.8 um long and from 18-25.8 um wide. There are 13 somatic kineties that reach the rear pole of the ciliate where they end forming a circle in the center of which the kinetosome of the organism's caudal cilia is located. The macronucleus, oval-shaped, is located in the front half of the ciliate, just above the equator and is from 13.2-14.4x3.6-12.6 um in size. The spherical micronucleus is generally located beside the macronucleus above its front surface and measures 4.2 um in diameter. The oral area is located on the left side of the ventral surface of the ciliate over its equator. The kinetosomes of the somatic kineties each have a thick kinetodesmal fiber. These fibers are arranged according to the law of desmodexy and measure from 0.9 to 1.2 um. Parasomal sacs have been frequently seen to accompany the somatic kinetosomes. (ref. ID; 4679)
  • Oral ciliature: There are 2 groups of principal structures: the paroral formation (PF) and the adoral zone of membranelles (AZM). The paroral formation is located on the right side and part of the posterior zone of the oral area; the ciliature of this structure is located on a thick fibrous formation that is strongly contrasted in the preparations. This fibrous formation (FF) has a sickle-like appearance and shows two thick projections toward the interior of the oral area, one at the front end of the straight part and the other at the rear end of the same straight part. In addition, the FF is extended towards the interior of the oral area by means of this extensions: two are located at the front end, in parallel, and more or less straight, pointing towards the left front side of the ciliate; one, curved, extends from the rear end of the curved part of the FF; the last two extensions tend to close the circle of the curved part of the FF. A paroral formation (PF) is located over the FF, composed of 2 rows of kinetosomes (stichodyad). This paroral formation is 10.8 um in length. The anterior end of the paroral formation is 9.6-10.8 um from the front pole, and the rear end of the paroral formation is 17.4- 21.6 um from the front pole. The adoral zone of membranelles (AZM) is located at the left side of the oral area of the ciliate. It is composed of 3 membranelles: M1, M2 and M3, the furthest of which (M1) is lined up before the PF. The other membranelles (M2, M3) are more or less lined up with the PF. The length of the oral area from the anterior end of M1 until the base of the paroral formation is from 10.2-12.6 um. The M1 membranelle is the furthest to the front, and is located at 4.8 um of the anterior pole of the ciliate and is made up of a single row of six kinetosomes. This row is from 2.1-2.4 um in length. Membranelle M2 is located in such a way that its middle is more or less in front of the anterior end of the PF; it is composed of three rows of six kinetosomes each and is of 2.4-2.7 um in length and from 1.2-1.8 um in width. Membranelle M3 is the furthest to the rear and is located in front of the posterior segment of the straight part of the paroal formation, just above the level of the thick projection of the rear end of the FF; this membranelle is made up of three rows of three kinetosomes each and is of 1.5-2.1 um in length and of 1.2-1.8 um in width. The scutica of the ciliate is located under the PF of the ciliate, at a distance of 1.2-1.5 um from the posterior curved part of the paroral formation; it is made up of three to four kinetosomes. (ref. ID; 4679)

    Comments

    U. castellonensis is the species that is most similar to Uronema nigricans (Thompson and Evans 1968) with respect to size (U. nigricans measures from 21-29x11-14 um, U. castellonensis measures from 28-37x18-25 um). U. nigricans has 12 somatic kineties and U. castellonensis has 13. The macronucleus of U. castellonensis is considerably larger than the macronucleus of U. nigricans (13-14x9-12 um in U. castellonensis, 8.5x6.5 um in U. nigricans). The undulating (paroral formation) is shorter in U. nigricans (6.9 um) than in U. castellonensis (10.8 um). The U. nigricans described by Wilbert and Kahan (1981) has 11 somatic kineties. There are also differences with respect to the size and composition of the membranelles. M1 only has a single row of 5 kinetosomes, 2.2 um in length, in U. nigricans of Wilbert and Kahan (1981) and measures 1.6 um in length in U. nigricans of Thompson and Evans (1968); the M1 in our species has 6 kinetosomes and measures from 2.1 to 2.4 um in length. The M2 measures 1.6x1.1 um in U. nigricans of Thompson and Evans and has a length of 1.9 um in U. nigricans of Wilbert and Kahan; in U. castellonensis, M2 is from 2.4-2.7x1.2-1.8 um in size and has 3 rows of six kinetosomes each. M3 of U. nigricans of Thompson and Evans is 3x1.3 um in size, M3 of U. nigricans of Wilbert and Kahan is 1.4 um in length; M3 of U. castellonensis is from 1.5x 1.2-1.8 um in size and has three kinetosomes each. Other differences may be noted in the composition of the somatic and buccal infraciliature (kinetodesmal fiber, structure of the paroral formation) and in connection with the fibril systems (Evans and Corliss 1964; Thompson 1964, 1968, 1966; Small 1967; Corliss 1979). (ref. ID; 4679)

    Uronema elegans Maupas, 1883 (ref. ID; 1622, 2085, 4524) reported author and year? (ref. ID; 7213)

    Descriptions

    Analysis of the internal transcribed spacer 2 (ITS2) region. (ref. ID; 7213)

    Uronema filificum Kahl, 1931 (ref. ID; 645, 1622, 2085, 4523, 4524) reported year? (ref. ID; 3846)

    See

    Uronemella filificum (ref. ID; 4523)

    Descriptions

    Length ca. 30 um; ovoid, broadened at the front, mouth in a depression behind the middle, distinct frontal plate. Nuclear apparatus comprises a macronucleus and a micronucleus in the anterior region. Cilia long, ca. 10 um, in 18 kineties. Kineties 1 to 17 polar, kinety 18 ends next to membranelles 1. Caudal cilium almost as long as the body. Contractile vacuole terminal. The animals attach themselves to detritus by the caudal cilium and produce a thread of mucus several times the length of the body, on which they hang and rotate. When detached U. filificum does not adopt a resting posture. The ration of the body is evidently made possible by a special arrangement of the cilia. In most of the kineties the kinetosomes are paired anteriorly and single toward the back. Kineties 16, 17 and 18 differs from this pattern, having paired kinetosomes throughout their length. In fact, the kinetosomes are closer together near the caudal end than at the front, and the caudal cilia are more sturdy than those on the rest of the body. The tuft of cilia so formed is indubitably significant in locomotion. The silverline system has the structure typical of Uronema. The posterior circular fibril is open. The excretory pore is at the end of the 2nd kinety. The basal-body complex opens into the posterior circular fibril between meridians 11 and 12. Membranelle 1 consists of a row of 6 kinetosomes, and lies 3 um away from the anterior pole. (ref. ID; 645)

    Comments

    The most confused species Uronema filificum was first transferred into a new genus Uronemita by Jankowski (1980) as the type species without giving any diagnostic description, and then was transferred into the genus Urocyclon by Small and Lynn (1985) without description or definition. Song and Wilbert erected Uronemella on base of generic characteristic: thigmotactic uronematid with pear-shaped body and subequatorially positioned cytostome; dominant apical plate; Uronema-like oral apparatus. The type species Uronemella filificum and other two related species, U. binucleata (Song, 1993) Song and Wilbert and U. cymruensis (Perez-Uz and Hope, 1997) Song and Wilbert were accomodated in the genus. (ref. ID; 4523)

    Uronema marinum Dujardin, 1841 (ref. ID; 1622, 1896, 2085, 2245, 2316, 3119, 3593, 4524, 4893) reported year? (ref. ID; 1219, 1618, 3771) reported author and year? (ref. ID; 191, 4611, 7536)

    Synonym

    Loxocephalus putrinus Kahl, 1926 (ref. ID; 1621)

    Descriptions

    Body long, ovoid; anterior pole without cilia and somewhat asymmetrically curved; cilia are arranged in about 15 longitudinal rows; the rather short triangular buccal cavity is situated anteriorly and bears 1 small external undulating membrane and 3 adoral membranelles in its depth; the total length of the buccal cavity is about 1/6 of the body length; the spherical macronucleus is located in the region of the mouth, a single micronucleus lies close to it; contractile vacuole at the posterior end of the cell. U. marinum forms resting cysts in starved cultures; conjugation is by fusion of the anterior ends of the body. Sometimes polymorphic. (ref. ID; 1219)
    In salt water among algae. (ref. ID; 1618)
    Caudal cilium equal in length to the body which was oval and measured 40 um. (ref. ID; 2316)

    Measurements

    Length 30-50 um. (ref. ID; 1219, 1618)

    Uronema nigricans (O.F. Muller, 1786) (ref. ID; 4524), (O.F. Muller, 1786) Florentin, 1901 (ref. ID; 645, 4488, 4611) or Florentin, 1901 (ref. ID; 1629, 2085) reported author and year? (ref. ID; 191, 3954)

    Synonym

    Cyclidium nigricans O.F. Muller, 1786 (ref. ID; 4611); Uronema parduczi Foissner, 1971 (ref. ID; 4611)

    Descriptions

    Body a long oval; length/width 20 um to 12 um. An elongated caudal cilium. Contractile vacuole terminal. Swims about without pause. The buccal infraciliature can be described as follows: Length of undulating membrane 6.6 um; distance from base of undulating membrane to anterior end 13.2 um; length of M1 2.2 um (beginning 3.3 um behind the anterior end), of M2 1.9 um, and of M3 1.4 um. In contrast to membranelles 2 and 3, M1 consists of only one row of 5 kinetosomes. This is a diagnostic feature of the genus Uronema. Number of kineties 11, each with 26 to 32 kinetosomes paired anteriorly and single posteriorly. The silver line system consists of meridional and commissural lines. The meridional silverlines open into a closed circular fibril at the anterior pole and, with the exception of kinety 11, into an open circular fibril at the hind end. Kinety 11 passes cross the caudal pole and joins the posterior circular fibril between kineties 6 and 7. The meridional silverlines are connected by two commissural silverlines in the anterior half of the animal. Two other commissural lines join kinety 11 with the silverline system of the peristome. (ref. ID; 645)

    Uronema pluricaudatum (Norland, 1937) (ref. ID; 1308, 1335, 1618, 2085)

    Descriptions

    Body appears to be twisted in dorsal view, due to a spiral depression that runs obliquely down toward cytostome; with about 8 caudal cilia; in salt water. (ref. ID; 1618)