Meseres
Meseres Schewiakoff, 1892 (ref. ID; 2014)
Class Polyhymenophora: Subclass Spirotricha: Order Oligotrichida: Suborder Oligotrichina (ref. ID; 2014)
Family Halteriidae Claparede & Lachmann, 1853 (ref. ID; 4356)
[ref. ID; 2014]
Body contractile, pyriform or trumpet-shaped, swimming broad end forward. At times the elongate species could be mistaken for a small Stentor except that in Meseres the peristomial field is not ciliated. Conspicuous open AZM winding around the apical pole of the body which is completely ciliated by many (20-40) longitudinal kineties. Single contractile vacuole laterally placed without serving canals. Macronucleus spherical, centrally located.
Most easily confused with Stentor.
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; 3389]
Considerably large size (40-130 um). The body is variable in shape, obovoid to "heart" shaped, but one species shows an elongated form. The peristomial field is flat with no ciliation where apical membranelles are encircled. Somatic cilia are present forming longitudinal rows. All species found in freshwater. (ref. ID; 3389)
- Meseres cordiformis Schewiakoff, 1892 (ref. ID; 3388, 3389) or 1893 (ref. ID; 1621) reported year? (ref. ID; 4356)
- Meseres corlissi Petz & Foissner, 1992 (ref. ID; 4356 original paper) reported author and year? (ref. ID; 191)
- Meseres oblongus (Kellicott, 1885) n. comb. (ref. ID; 4356)
- Meseres stentor Schewiakoff, 1892 (ref. ID; 3389) or 1893 (ref. ID; 1621) reported year? (ref. ID; 4356)
Meseres cordiformis Schewiakoff, 1892 (ref. ID; 3388, 3389) or 1893 (ref. ID; 1621) reported year? (ref. ID; 4356)
Descriptions
The body is variable in shape. When it stretches, it has an obovoid form with a small peristomial field. During contraction, the body is a "heart" shape with a depressed peristomial field and archedly projected lateral sides. The circlet of apical membranelles is open. The somatic surface has longitudinal furrows along which fine, short cilia arise, producing rows. The endoplasm contains granules. The macronucleus is ovoid and situated in the central area with an associated micronucleus. A contractile vacuole is present at the left side, just posterior from AZM. A freshwater species. (ref. ID; 3389)
Measurements
Size, 40-72 um. (ref. ID; 3389)
Meseres corlissi Petz & Foissner, 1992 (ref. ID; 4356 original paper) reported author and year? (ref. ID; 191)
Diagnosis
In vivo about 70-90x60 um, acontractile. Eight slightly shortened somatic kineties in equatorial portion; cilia long, not fused to "bristles". Sixteen anterior and 15 ventral adoral membranelles on average. (ref. ID; 4356)
Descriptions
Broad-ellipsoid, widest close below anterior adoral membranelles (anterior polykinetids), rarely slightly tapering posteriorly. Transverse section circular. Macronucleus ovoid to slightly reniform, approximately in mid-body left of cytostome, contains small and large, globular to band-like nucleoli. Single, spherical micronucleus in indentation of macronucleus. Contractile vacuole ventro-laterally left of oral cavity in anterior body half; temporary excretory pore between 2nd and 3rd somatic kinety. Cytopyge near posterior end, disproving the assumption that it is entirely absent in oligotrichs (Corliss 1979). Cortex thin, flexible, with plate-like layer of, probably, numerous mitochondria (2-3x1-2 um). Cytoplasm usually packed with food vacuoles containing green algae (4-7 um in diameter), some greasy shining globules (1-3 um in diameter) and irregularly shaped crystals (ca. 1 um). These inclusions render cells almost black at low magnification. Some individuals with vacuolized cytoplasm. Movement gyrating and jumping, never rests. Somatic kineties slightly spiralling composed of rather closely spaced cilia, take clockwise turn when viewed from anterior to posterior pole. Close to each ciliated basal body is a smaller, non-ciliated granule from which (as from the ciliated basal body) a long, lateral fiber originates, indicating that the somatic kineties are very likely composed of dikinetids (so designated in the further description). Fibers, like those found in Halteria (Grim, 1974), sometimes extend more than half the distance to adjacent kineties but, apparently, are not connected. The non-ciliated basal bodies are sometimes recognizable as very small knobs in the SEM. Cilia about 16x0.5 um, remarkable both in structure (uniformly thick; cp. more needle-like cilia in Halteria) and physiology (rather stiff, do not beat like normal cilia). One to two dikinetids with one cilium each (ca. 15 um long) in small fold close to lower right margin of oral opening; they possibly possess a long, anteriorly extending fiber. Anterior adoral membranelles distinctly separate from ventral membranelles, conspicuous, surround anterior end of cell; cilia about 35 um long, fused proximally, frayed distally. Each anterior membranelle composed of three equally long ciliary rows (about 12-14 um); first membranelle to right of oral cavity slightly shortened (average=10.7 um). Ventral adoral membranelles consist of four rows of basal bodies each: two equally long, one shorter and one very short row; cilia about 10 um long. Ventral and anterior membranelles each connected by system of fibers. Paroral membrane on inner right side of oral cavity, extends to center of peristomial surface. Cytopharynx lined by few, short fibers. (ref. ID; 4356)
Morphogenesis: Numbering of kineties follows (Deroux 1974). Row one is nearest to the cytostomial region and counting continues clockwise around the cell when ciliate is viewed from posterior. The oral primordium originates apokinetally slightly below mid-body between the 1st and the 2nd somatic kinety, i.e. in a ventro-lateral position. Very early stages show only a few basal bodies which soon develop to a falciform, posteriorly narrowed anarchic field. The adoral membranelles begin to differentiate at the anterior end and on the right side of the anlage, respectively. During this process a short row of single granules develops as an anlage for a somatic kinety between the posterior ends of parental kineties 2 & 3. Resorption of the non-ciliated granules starts at the aboral ends of somatic kineties 1 & 2. In the next stage, the anterior and ventral membranelles can be distinguished. Right of these, the paroral membrane forms without apparent contact with the adoral membranelles, indicating a likely de novo origin. The resorption of the non-ciliated basal bodies (granules) is now recognizable in all somatic kineties and proceeds anteriad. Except between kineties 8 & 1 and 1 & 2, two somatic anlagen originate de novo between each of two parental rows. Between kineties 8 & 1 only one row of basal bodies is formed which later becomes the opisthe's kinety 1. The anlage for the proter's kinety 1 develops left of the anterior end of the parental kinety 1 which is very close to the posterior rim of the oral cavity. Thus, three somatic anlagen are recognizable between kineties 1 & 2. Subsequently, the somatic granule (another kinetosome?) appears very close to each basal body; these granules are sometimes visible in the SEM as very small knobs, as in H. grandinella. The granules from the parental kineties and from the dikinetids near the oral cavity are by now entirely absent, leaving ciliated monokinetids which are apparently resorbed during the very last stages of cytokinesis. Next, the ventral adoral membranelles of the opisthe rotate clockwise about 90-100 degrees and invaginate; the anterior membranelles spread to enclose the apparently fully differentiated peristomial surface in an incomplete circle. A very prominent spiral of adoral membranelles is now visible on the posterior ventral side of the cell. During this rotation, the anlage left of the ventral membranelles moves onto the ventral side and becomes the opisthe's kinety 2; the anlage between parental kineties 8 & 1 rotates about 90 degrees and becomes somatic kinety 1. The basal bodies near the opisthe's oral cavity develop de novo. Apparently, the parental oral ciliature (anterior and ventral membranelles, paroral membrane) is not renewed. The micronucleus has divided and the distinctly elongated macronucleus is filled with chromatin filaments. A macronuclear replication band was only rarely found in early and late divisional stages. Such nuclei occasionally contain one large, elongated nucleolus. We did not find very late dividers. (ref. ID; 4356)
Generic position and comparison with related species
Schewiakoff (1893) diagnosed Meseres as follows (translated from German): "As regards the oral organization, Meseres is a typical Oligotricha and is mot similar to Halteria or Strombidium. However, it differs markedly from these genera by its complete somatic ciliature which, although sparse, has not entirely vanished." Our species matches this diagnosis perfectly. Meseres differs from the genera Halteria Dujardin, 1841 and Pelagohalteria Foissner et al., 1988 by its much more complete, non-polymerized somatic ciliature. The somatic kineties of Halteria are very short and most of the ciliature fused to so-called "bristles" (Fernandez-Leborans 1983; Grain 1972; Grim 1974; Tamar 1974). Pelagohalteria possesses fused cilia like Halteria and an additional horizonal row close below each "bristle complex" (Foissner 1988). The few cilia to the right of the oral opening in H. grandinella and M. corlissi confirm their close relationship. Meseres cordiformis Schewiakoff and M. stentor Schewiakoff differ from M. corlissi by having a higher number of somatic kineties (usually 16 or more), shorter somatic cilia, and a pronounced contractility (about 40% of body length (Schewiakoff 1892, 1893)). Another species, Strombidium oblongum (syn. Halteria oblonga (Kahl 1932), shares the peculiar somatic ciliature with M. corlissi (Kahl 1932; Kellicott 1885). Although a detailed study of its infraciliature is lacking, the data indicate that it should be transferred to Meseres: M. oblongus (Kellicott, 1885) n. comb. This species is distinctly smaller (25-45 um) and has 6-7 somatic kineties with "soft" (flexible) and widely spaced cilia. Trailing cilia, as long as the body, are at its posterior end. Like M. corlissi, it is acontractile. Meseres oblongus is associated with the algae Chaetophora (Kahl 1932; Kellicott 1885; Penard 1922). Mirabdullajev illustrates Metastrombidium nigrum as having long somatic kineties. In the description, however, he states that it has "no somatic ciliature". Thus, it cannot be definitely assigned to Meseres. (ref. ID; 4356)
Etymology
We dedicate this new species to Professor John O. Corliss as a small token of appreciation for his friendship and encouraging discussion over many years. (ref. ID; 4356)
Type location
Dried mud from an astatic meadow-pond between the so-called Henkerhaus and the Peterweiher, City of Salzburg Austria, 47 degrees 47'N, 13 degrees 02'E. (ref. ID; 4356)
Type specimens
A holotype and a paratype of M. corlissi as two slides of protargol impregnated cells have been deposited in the collection of microscope slides of the Oberosterreichisches Landesmuseum in Linz, Austria. Accession numbers: 3, 4/1991. (ref. ID; 4356)
Meseres stentor Schewiakoff, 1892 (ref. ID; 3389) or 1893 (ref. ID; 1621) reported year? (ref. ID; 4356)
Descriptions
The body is elongated and widened in the middle. The posterior area is narrowed and slightly pointed at its extremity. The peristomial field is flat with no ciliation. Somatic cilia are fine and short and form longitudinal rows. The macronucleus is ellipsoid and a contractile vacuole is situated at the left side of the anterior area. A freshwater. (ref. ID; 3389)
Measurements
Size, 130 um. (ref. ID; 3389)