Saprodinium

1. Saprodinium dentatum Lauterborn, 1901 (ref. ID; 1621) or 1908 (ref. ID; 4327) reported year? (ref. ID; 1219, 1618, 3690), (Lauterborn, 1901) Lauterborn, 1908 (ref. ID; 4610) reported author and year? (ref. ID; 4818)
   Syn; Discomorpha dentate Lauterborn, 1901 (ref. ID; 4610)
2. Saprodinium difficile (ref. ID; 7234)
3. Saprodinium halophilum Kahl (ref. ID; 3771) reported author and year? (ref. ID; 1621)
4. Saprodinium integrum Kahl, 1928 (ref. ID; 1335, 1621)
5. Saprodinium mimeticum Penard, 1922 (ref. ID; 1621)
   Syn; Saprodinium tortum Kahl, 1926 (ref. ID; 1621)
6. Saprodinium putrinum Lackey, 1925 (ref. ID; 1308, 1621, 4610) reported year? (ref. ID; 1618)
7. Saprodinium triangulum (ref. ID; 1621)

Saprodinium dentatum Lauterborn, 1901 (ref. ID; 1621) or 1908 (ref. ID; 4327) reported year? (ref. ID; 1219, 1618, 3690), (Lauterborn, 1901) Lauterborn, 1908 (ref. ID; 4610) reported author and year? (ref. ID; 4818)

Synonym

Descriptions

Remarks

• Frontal band: The so-called frontal band composed of the anterior ciliated segments of five somatic kineties (SK3-SK7) is especially conspicuous. Together with the two frontal kineties, which are the anterior ciliated segments of SK1 and SK2, the frontal band is the main locomotory organelles for the creeping of the cell on the substratum. The anterior part of the frontal band starts on the cell's left side, runs over the ventral ridge, and tapers off on the cell's right in a slight curve. The longitudinal axes of its parallel kineties are more or less perpendicular to the anterior-posterior axis of the cell. The frontal band kineties consist of ciliated dikinetids. The frontal band kineties (SK3-SK6) start at the same line on the cell's left side except for the most anterior one (SK7) that begins one dikinetid later. On the cell's right side, all frontal band kineties "end" in a staggered manner. Adjacent frontal band kineties differ in length by 4-7 dikinetids, the most anterior frontal band kinety is the longest, while the most posterior of the frontal band kineties is the shortest. As seen easily by comparing silver-stained specimens and scanning micrographs, SK3-SK7 continue with non-ciliated segments, either seen as lines of particularly dense silver deposits or as small pits in the pellicle. (ref. ID; 4327)
• Spine and spine kineties: Saprodinium dentatum is characterized by numerous spines. A single spine in the middle of the ventral ridge close to the oral apparatus called oral spine because of its location. The frontal spine, a single spine near the anterior cell pole (Kahl 1932) is the anterior continuation of the dorsal a ridge that ends posteriorly in the dorsocaudal spine. The anterior third of the dorsal ridge laterally flattens, has a thickness of less than 1 um, and is called the dorsal keel. There are three caudal spines (CS9, CS10, CS11) on the left side of the cell; CS11 is slim and located nearest to the ventral ridge. As discussed later, CS 11 is the only caudal spine without a clear-cut association to a somatic kinety. The other two caudal spines (CS9 and CS10) on the cell's left side bear caudal spine kineties made of 9 or 10 ciliated dikinetids. The right side of the cell shows four caudal spines (CS4-CS7). The one located ventralmost (CS4) is so small that it is often overlooked and can be considered a rudiment. Only the fourth spine on the right side (CS7), the one located dorsalmost, bears a short spine kinety consisting of three pairs of ciliated kinetosomes. This tiny ciliated kinety segment can be considered the posterior end of the fifth frontal band kinety (SK7). The spine kinety associated with CS7 is shifted out of the normal kinety plane. The other caudal spines on the cell's right side bear no spine kineties, but silver-stained preparations show a spatial relationship between the non-ciliated segments of the somatic kineties and the caudal spines. The dorsocaudal spine (CS8) bears a spine kinety on its right side that consists of about 12 dikinetids and is the posterior ciliated segment of the long somatic kinety SK8 running on the right side of the dorsal ridge. The ventrocaudal spine (VCS) lies posteriorly on the ventral ridge. The VCS flattens laterally and has a small process on its middle part. It is the only spine that has more than one spine kinety, namely two on its left side (CSK1 and CSK2) and one on its right side (CSK3). (ref. ID; 4327)
• Other somatic kineties: Below the frontal band on the ventral ridge are two adjacent kineties, called frontal kineties, that we regard as the anterior ciliated segments of the two SK1 and SK2. As mentioned above, their anterior parts are involved in a creeping locomotion. The anterior parts of the frontal kineties run parallel to the anterior part of the frontal band kineties, then they turn posterior for more than 90 degrees, and then run toward the ventrocaudal spine. The presumed posterior continuation of these two kineties are the two isolated ciliated spine kineties (CSK1, CSK2) on the left side of the ventrocaudal spine. These spine kineties are involved in a swimming-type locomotion. Between the second frontal kinety and the corresponding spine kinety is a short ciliated segment consisting of three pairs of kinetosomes seen both in silver-stained specimens and in SEM. In the latter micrograph, the tiny middle segment of SK2 is covered partly by the so-called preoral cilia (POC) that belong to the oral ciliature. Contrary to other somatic kineties, there are no barren kinetosomes in SK1 and SK2. Nevertheless, it is tempting to interpret the short ciliated middle segment as the remainder of a somatic kinety that was once continuous. At least in silver-stained preparations, SK10 is the dominating somatic kinety on the cell's left side. In reality this left somatic kinety is non-ciliated over most of its length, showing cortical pits in SEM similar to those seen for SK6. These pits are diagrammed also together with particularly long cilia of CSK10. The right dorsal kinety (SK8) and the left dorsal kinety (SK9) run on either side of the dorsal ridge. Somatic kinety no.8 has a long non-ciliated segment, its silver-stained kinetosomes are a ciliated posterior segment associated with the dorsocaudal spine (CS8). The non-ciliated segment of SK8 shows what will be called kinety torsion, a phenomenon often seen in ultrathin sections within the flattened anterior part of the dorsal ridge. Sites of kinety torsion, which also may be found in other somatic kineties. The structural basis for this phenomenon will be discussed later. Somatic kinety no.9 has a very long ciliated segment consisting of some 80 ciliated dikinetids. Compared with the sparse ciliation of SK8, it is reasonable to call SK9 the dorsal kinety in the literal sense of the word. Its cilia arise from the right slope of the dorsal ridge. Corresponding kinetosomes are spaced closely. The ciliated segment of SK9 reaches beyond the middle of the dorsal side. In silver-stained preparations, the non-ciliated segment of SK9 (the non-ciliated status known from SEM) stretches about 1.4 times when further compared with other non-ciliated kineties. As we discuss later, this kinety stretching is considered a form of kinety-instability, which my have its cause in the peculiar fine structure of the non-ciliated segments. Somatic kinety no.9 ends with a ciliated segment on CS9. Finally, we described for the first time anther short kinety on the cell's left side. As already mentioned, this kinety is called inverse kinety (IK) because its three dikinetids show an inverse orientation with respect to the anterior-posterior axis of the cell. Its six kinetosomes do not appear clearly in silver-stained preparations. They usually show up as one oval spot, which is not easily identified as a short kinety. Six cilia are easily counted. The IK is the only kinety which shows no clear association with a caudal spine. While the IK obviously lies close to the oral spine, the third spine on the left side (CS11) is not associated with a somatic kinety, a feature that will be discussed later. A particularly prominent fibrillar network connects this kinety to the frontal kineties. A few single or paired non-ciliated kinetosomes, not associated with parasomal sacs, were found in this sections just above the fibrillar network. In the ciliated segment of this kinety, each pair of kinetosomes is associated with a ribbon of about eight microtubules. These microtubules, positioned tangentially with respect to their kinetosomes, are regarded as transverse microtubules belonging to the anterior kinetosome of the somatic dikinetids of an inverse kinety, whose kinety axis now points with its anterior toward the posterior pole of the cell. These rare parasomal sacs in the ciliated segment of the inverse kinety, but postciliary microtubules seem to be lacking. (We note that the parasomal sacs shift to the kinety's right side. When seen from the cell's outside, an inverse kinety has its right side on the right side of a micrograph, which has been mounted with the anterior pole of the cell pointing toward the upper end of the plate.) (ref. ID; 4327)
• Ciliated segments of the somatic ciliature: The ciliated segments of the somatic kineties SK1-SK10 of S. dentatum consist of dikinetids. The posterior kinetosome of each dikinetid is associated with a radially arranged ribbon of about five postciliary macrotubules. The anterior kinetosomes shows a tangentially arranged ribbon of about eight transversal microtubules. Each dikinetid is associated with a typical parasomal sac which often shows endocytotic activity. In some details the dikinetid pattern of S. dentatum is similar to the heterotrich-karyorelictid dikinetid pattern (Lynn 1981) that lacks the parasomal sac. The ciliated dikinetids within the somatic kineties are connected by an electron-dense fibrillar intrakinetal network. Similar interkinetal networks also exists in the area where the frontal kineties lie close to the frontal band kineties, and within the frontal band itself. Depending on the position of dikinetids within a frontal band kinety, the distance between two of them is different; it is much greater on the right side than on the ventral ridge. The angle between the dikinetid pair axis and the axis of the kinety gradually changes; the angle is about 45 degrees in the posterior of a frontal band kinety located on the right side of the cell and only about 5 degrees on the ventral ridge. In contrast the other ciliated segments, namely the spine kineties, the dorsal kinety and the frontal kineties have the same angle of about 90 degrees included between the dikinetid axis and kinety axis. (ref. ID; 4327)
• Non-ciliated segments of the somatic ciliature: The non-ciliated segments of SK3-SK10 require a more detailed description primarily based on ultrastructural observations. In these segments obvious of an instability of kinetosome arrangement are seen in thin sections. For example, the longitudinal axis of the kinetosomes can be turned for >90 degrees around the axis of the kinety. Occasionally cross-sections of kinetosomes with inverse orientation of the nine triplets were seen, in all probability the result of kinety-torsion of 180 degrees. All non-ciliated segments of kineties show kinetosomes arranged in pairs. Important exceptions are explained later. Kinetosomes in the non-ciliated segments definitively lack the microtubular and fibrillar systems normally associated with somatic kinetosomes. The fibrillar network, which is below the ciliated segments of the somatic kineties is also lacking. Few microtubules run left of the proximal end of the kinetosomes in an orientation parallel to the longitudinal axis of the kinety. Neither the distance between the kinetosomes nor the angle between a pair axis and the kinety axis are constant, but changes in a wide range. Between two neighboring pairs of kinetosomes is a voluminous parasomal sac. There is another important feature for the interpretation of the kinetosome pairs. Non-ciliated segments of the somatic kineties always begin and end with a single kinetosome. Careful analysis of such a transition from a ciliated to a non-ciliated kinety segment shows the following details: the ciliated segment consists of proper dikinetids (with a parasomal sac in the crater-like depression surrounding the two cilia), followed by a single kinetosome at the beginning of the non-ciliated segment, then a voluminous parasomal sac, two kinetosomes which seem to be a pair, a parasomal sac again, and so on. According to our interpretation, in non-ciliated segments it is not the two closely adjacent kinetosomes which belong to a dikinetid, but those kinetosomes which are separated by the voluminous sac. (ref. ID; 4327)
• Oral apparatus: The oral apparatus of S. dentatum consists of the oral cavity, oral ciliature, and the cytostome-cytopharynx complex. First we give a survey of these two components before dealing with some special aspects. The oral cavity of S. dentatum is a complex tripartite structure. The larger posterior part (the outer oral cavity) contains eight parallel adoral membranelles and an additional group of preoral cilia, and the second smaller part (the inner oral cavity) that is subdivided into a small sickle-shaped part and a larger part containing a single membranelle. The oral ciliature of S. dentatum consists of 9 or 10 adoral membranelles previously mentioned in connection with the oral cavities. Even by light microscopy each membranelle is clearly seen composed of three longitudinal rows of cilia. Eight adoral membranelles are located in the outer oral cavity and a ninth adoral membranelle (AM9) is found in the inner oral cavity. In addition, there is another small group of nine cilia, called preoral cilia (POC) by Kahl (1932), that may or may not disturb the numeration of membranelles. The peculiar location of the POC shifted toward the frontal ridge and arising from a more elevated position compared with the other members of the adoral zone of membranelles (AZM). It must be emphasized that Saprodinium, at least in fully differentiated trophic state, has no paroral ciliature. No matter which technique was applied, there is not the slightest trace of a paroral ciliature, e.g. no barren kinetosomes, no ribbed wall. The complex shape of the outer and inner oral cavities and the connections between these cavities, as well as the position of the cytostome-cytopharynx complex require further comments. Visible only by electron microscopy, the inner oral cavity is divided by a curtain-like septum into an anteriorly positioned chamber with a sickle-shaped cross-section in lateral view, and a second wider chamber with the cytostome located at the dorsal wall. The septum separating the two chambers of the inner oral cavity does not reach the bottom of the cavity, but leaves a slit-like opening between the two chambers. The function of the sickle-shaped chamber is not known. The inner oral cavity and the outer oral cavity seem to have two connections (CN1 and CN2). Connection CN2 is a winding tube below the epiplasm of the left side of the cell, distal to the plane of membranelles. Connection CN1 is short. The cytostome is located in the dorsal wall of the middle chamber and is continuous with a long thin tube-like cytopharynx (oriented toward the middle of the dorsal ridge of the cell). Thus, the cytopharynx is perpendicular to the anterior-posterior axis of the cell. Cells fixed in osmium vapor show the cytopharynx identified by its tube-like shape and the unusual orientation to other cell structures. Starting with a larger diameter, over most of its length the cytopharynx is only 0.2 um in diameter; it measures 10 um in length. It is surrounded by an inner sheet of parallel microtubules and several cytopharyngeal lamella likewise made up of microtubules. We assume that some of these microtubules are identical to those originating from kinetosomes of the adoral membranelles. We agree that these microtubules arising from the anterior edge of AM9 are postciliary ones. Finally, it should be noted that the cytostome is located anterior to the AZM. Fibrillar bundles at three ill-defined levels link the kinetosomes of a membranelles to one another and to the kinetosomes of adjacent membranelles. At the upper levels, the fibrillar bundles attach to an electron-dense ring, which encloses each kinetosome; at the middle and lower levels, the fibrillar bundles attach directly to the kinetosomes. Except for the few supposed postciliary microtubules in front AM9 of still questionable identity, no other microtubules are associated with the kinetosomes of the fully differentiated adoral membranelle. Anterior to the tube-like segment of the cytopharynx there are many irregular membranous vesicles with electron-dense content of unknown chemical nature. They could be lysosomes or hydrogenosomes; the latter often are found in anaerobic ciliates that harbor methanogenic bacteria (Van Bruggen et al. 1984). Furthermore, large food vacuoles contain the remains of membranes and bacteria. (ref. ID; 4327)

Examined material

Measurements

Saprodinium putrinum Lackey, 1925 (ref. ID; 1308, 1621, 4610) reported year? (ref. ID; 1618)

Descriptions

Measurements