Vannella Bovee, 1965 (ref. ID; 2093, 4882)
Family Vannellidae (Bovee, 1970) Page, 1987 (ref. ID; 4882)

[ref. ID; 2093]
Locomotive form flattened, with flabellate, spatulate, occasionally oval outline; fan-like hyaline veil occupying anterior quarter to half and usually extending around sides of granular mass; no pseudopodia during locomotion; no uroidal filaments. Floating form of most but not all species with rounded central mass and several slender, hyaline pseudopodia tapering to narrow tip. Surface always covered with delicate flexible structures (glycostyles) consisting of central tubule and five radial wings, approximately 95 to 120 nm in height above plasma membrane and 40 to 65 nm in diameter at base. Uninucleate. Nuclear division with nuclear membrane often but not always persisting in part or in whole through metaphase. No cysts known. Marine and freshwater. (ref. ID; 2093)

Vannella caledonica Page, 1979 (ref. ID; 1883, 2093 original paper)
Description; Marine species. (ref. ID; 2093)
[Light-microscopy]: In locomotion the amoebae are commonly flagellate, i.e., flattened with a triangular outline and a deep, arc-like anterior hyaline zone (veil), the anterior edge of which is often but not always wavy. The posterior end sometimes tapers to a narrow tip. The hyaline zone may divide temporarily as the amoeba pushes forward simultaneously on both sides at an angle to its previous line of advance. At times the tapered posterior end is drawn up into the main mass. Flow of the granuloplasm is easily observed. The hyaline zone, measured at the midpoint, occupies from 0.3 to 0.5 of the length of the amoeba. The locomotive rates of 10 amoebae of strain 212 at 23 degrees were 23 to 30 um per minute, or 1.3 to 2.0 times the lengths. Those of 213 at 28 degrees were 22 to 47 um per minute, or 1.6 to 2.3 times the length. The floating forms produced never put out any radiate pseudopodia. This observation was made in repeated examinations of many cells of strain 212 and at least two examinations of many cells of strain 213. The nucleus has the structure most common in small and medium-sized amoebae, with a central nucleolus. It is, as usual, somewhat deformable during cytoplasmic flow. In nuclear division, the nucleolus disappears during prophase. In early metaphase, the nuclear membrane is still present, with a slight deposit sometimes seen on its inner surface. In at least one metaphase figure, with the chromosome (individually not distinguishable) in a well-formed ring, no nuclear membrane was seen. However, one early anaphase had a suggestion of remnants of membrane along either side of the spindle, though no nuclear membrane at all was left in another anaphase little if may more advanced. There seems to be some variation in the time of disappearance of the nuclear membrane, as reported by Page (1968) for Vannella mira. No centriole-like body was seen. Amoebae of this species are well rounded up by late metaphase, sometimes with a thin, flattened hyaline edge. (ref. ID; 2093)
[Electron-microscopy]: External to the plasma membrane is an amorphous basal layer about 8 nm thick, in which are embedded the bases of glycostyles identical in structure and very close in size to those of the freshwater species. Each consists of five flat wings radially arranged around a central tubule, with which they fuse. At a narrow neck in the distal half of each glycostyle, the wings are reduced to thickenings in the central tube, and the entire structure then flares toward the distal end, with traces of the wings remaining. Since the glycostyles are flexible and move in relation to each other, the measurements vary in sections, but the height of the tip above the plasma membrane was about 94 nm and the diameter of the glycostyle approximately 38 nm at the base, 13 at the neck, and 17 at the tip. Scattered amongst the glycostyles are a smaller number of slender simple filaments, up to 281 nm long. The function of the glycostyles, this adhesion to a bacterium accords with the idea of the glycostyles as sticky structures. Young food vacuoles are lines with a coating, including glycostyles, similar to that on the surface, though such a coating is absent in more advanced digestive vesicles. Some of the rounded vesicles with a very distinct coating resembling the cell surface appear to be carrying membrane for renewal of the surface. Among internal organelles, the mitochondria appeared somewhat less well fixed than others. They were oval to sausage-shaped, the longest seen measuring 1.28 x 0.64 um. The cristae were tubular and anastomosing. The central part of some mitochondria was empty of cristae but contained filaments, and it is not entirely certain that this appearance is due to a deficiency of fixation. The sections examined contained up to two Golgi bodies per cell, neither closely associated with the nucleus. Each consisted of about five cisternae, which were less flatten than those of some other amoebae. The Golgi body as a whole, about 0.6 um wide, had no concave of convex side. The rough endplasmic reticulum consisted of isolated flattened cisternae bearing ribosomes. Filaments were seen here and there in the cytoplasm. The nucleus showed no unusual features. The central nucleolus was granular, sometimes with one dense patch. The perinuclear cisterna varied much in width, and the external surface of the nuclear envelope was studded with ribosomes. (ref. ID; 2093)
[Cysts]: Cysts have never been seen in either strain of V. caledonica. (ref. ID; 2093)
Measurements; Locomotive form with anterior edge often wavy; greatest dimension approximately 10 to 25 um, mean about 15 or 16 um; mean length: breadth ration 1.1 to 1.2; floating form without long, radiate pseudopodia; nucleus approximately 2.8 to 4.7 um, with central nucleolus; slender filaments, sometimes nearly 300 nm long, among glycostyles. (ref. ID; 2093)
Stock strain; The Culture Centre of Algae and Protozoa. (ref. ID; 2093)
Vannella devonica Page, 1979 (ref. ID; 2093 original paper)
Description; Marine species. (ref. ID; 2093)
[Light-microscopy]: In their locomotive form and behaviour these amoebae demonstrate in a diagrammatic fashion the characters of the genus, with a broad, flabellate outline in a large proportion of amoebae attached to the under side of a cover glass. The edge of the hyaline area is usually very smooth and more regular than that sometimes seen in V. caledonica. The hyaloplasm occupies the anterior 0.4 to 0.5 of the amoeba, measured in the middle, and often extends around the sides. The thickness of the amoeba increases gradually toward the posterior end, and which is often convex to pyramidal. The locomotive rates of ten amoebae (temperature about 22 degrees C) were 11 to 33 um per minute, or 0.9 to 1.9 times the lengths of the amoebae. Although the locomotive forms might be mistaken for a Platyamoeba, the radiate floating form is typical of a Vannella. A few minutes after suspension in liquid, a minority of cells take on the radiate form, with long, slender, hyaline pseudopodia, which are fairly fine at the tip but not sharply pointed even to the light microscope. These may become helical. They are often irregular distributed and dissimilar, so that the floating form is usually asymmetrical. The nucleus has peripheral nucleoli, which may appear to number from one to four, rarely five. These appear from hematoxylin preparations eventually to take the form of bands, which may be positioned more or less at right angles to each other. Depending on the angle of vision and the focal plane, one may see only one nucleolar mass, which may appear to be central, since the nucleoli are superimposed on each other from that angle, or one may in a given plane see the ends of two bands and hence apparently four nucleoli. However, from the variety of configurations seen, it is possible that the nucleoli grow from compact bodies to bands, and the fusion of nucleoli cannot be ruled out. It is, however, certain that the presence of multiple peripheral nucleoli is not simply an immediately post-mitotic stage but a character of the normal interphase nucleus as seen in other genera of Gymnamoebia. During nuclear division, the nuclear membrane is intact during at least part of metaphase, and distinct caps which appear to be remnant of the nuclear membrane are seen on the polar side of each chromosome set well into anaphase, perhaps to early telophase in some cases. No centriole was observed. The amoebae are well rounded up during the middle stage of mitosis, though they may become more discoid in late anaphase. (ref. ID; 2093)
[Electron-microscopy]: The glycostyles of V. devonica resemble those of V. caledonica and of the freshwater species of Vannella in every detail, including size, with allowance for variations due to flexibility and to angle of cutting. However, V. devonica, like the freshwater strain of V. mira, lacks the simple filaments found on V. caledonica, V. platypodia and V. simplex. The difference between hyaloplasm and granuloplasm (ectoplasm and endoplasm) was more marked at the electron-microscopical level than in V. caledonica, and cytoplasmic filaments in bundles were both more common and more prominent particularly in the outer region. Some longitudinally oriented filaments were seen in pseudopodia but not definite filamentous cores as in Vexillifera sp. or Pseudoparamoeba pagei. The oval to sausage-shaped mitochondria had tubular, anastomosing cristae. These mitochondria, often more slender than those seen in V. caledonica, had a maximum measured size of 1.17 x 0.37 um. As many as three Golgi bodies were identified in a single section, although some sections contained none. The se bodies had no particular positions. The cisternae, numbering approximately five, were flatter than those of V. caledonica, and the Golgi bodies, about 0.5 um wide often had a convex-concave form. Rounded or oval vesicles with a lining resembling the surface coat and possibly transporting renewal membrane to the surface were seen. Sacs which were sometimes but not always flattened and bore ribosomes on their external surface presumably comprised the endplasmic reticulum. In sections of nuclei, several nucleolar pieces or, more rarely, a single apparently central nucleolues were seen. Probable explanations have been given in the light-microscopical description. The common configuration had one larger and one smaller nucleolus against the nuclear envelope, with less compact aggregations of dark material which may have been chromosomal material often visible throughout the nucleus. The perinuclear cisterna had a more regular width than in V. caledonica, perhaps attributable to less swelling in fixation. (ref. ID; 2093)
[Cyst]: No cysts are known for V. devonica. (ref. ID; 2093)
Measurements; Locomotive form with anterior edge usually smooth and regular; greatest dimension approximately 14 to 33 um, mean approximately 22 um; mean length: breadth ratio 0.9; floating form sometimes with slender, radiate pseudopodia, with length sometimes more than twice diameter of central mass; nucleus approximately 3.7 to 5.6 um, with two or more peripheral nucleoli; no slender filaments among glycostyles. (ref. ID; 2093)
Stock strain; The Culture Centre of Algae and Protozoa. (ref. ID; 2093)
Vannella mira Schaeffer, 1926 (ref. ID; 2093, 2359, 2431)
Syn; Flabellula mira (ref. ID; 2093)
Description; Type species. Freshwater species. (ref. ID; 2093)
The glycocalyx of this species consists of a basal layer approximately 28 nm thick and glycostyles of the same structure and size as those of V. platypodia. Careful examination has not revealed any simple filaments on the surface of this species. (ref. ID; 2359)
Measurements; Length 25 um, breadth 15-25 um, a nucleus with a diameter of 5 um and a central nucleolus, and floating form with long pseudopodia. (ref. ID; 2093)
Vannella peregrinia Smirnov & Fenchel, 1996 (ref. ID; 4882 original paper)
Diagnosis; Locomotive form varies from broad fan-shaped to flagellate with a long, spatulate posterior end, but usually is irregularly semi-circular, often with a transverse, spindle-shaped thickening of the posterior part of the granular region. The frontal hyaloplasm occupies 1/3-2/3 of the total body length. The length of the locomotive form is 4.5-14 um (average: 9 um) and the breadth is 3-13 um (average: 8 um). The L/B ratio varies between 0.7 and 1.7 (average: 1.1). The floating form is twisted and wrinkled, without pseudopodia. Vesicular nucleus 2-3 um in diameter with a single, spherical central nucleolus in diameter with a single, spherical central nucleolus up to 0.6-0.9 um in diameter. The perinulear cisternae are enlarged and the external and the inner nuclear membranes make contact only at the sites of nuclear pores. The thickness of the basal layer of the cell coat is 10-13 nm; the length of the glycostyles is 42-60 nm. Simple filaments, up to 300 nm in length, are very abundant. Anaerobic. (ref. ID; 4882)
Comments; The locomotive morphology of this species (semi-circular or flagellate form with a long, spatulate posterior end) and the organisation of the cell coat (glycostyles) are characteristics of the members of the genus Vannella Bovee 1965, family Vannellidae (Bovee, 1970) Page, 1987 (Page 1983, 1988). But the glycostyles of the present species are much finer, shorter and more irregular than that of other Vannella spp. The fact that the glycostyles are identical in shape and size in all other marine and freshwater Vannella spp. (Page 1980; Page & Blakey 1979) does not support the inclusion of the present species in this genus. On the other hand, the glycostyles in V. peregrinia were not preserved sufficiently well to reconstruct their structure with certainty. An alternative generic home for this species could be the genus Platyamoeba, but all the species of this genus are very homogenous with respect to the organisation of their cell coat (Page 1980; Page & Blakey 1979). The formation of the posterior spatulate projection and the temporary existence of two hyaline zones, moving in different directions are also not characteristics of Platyamoeba, but they are typical for Vannella (Page 1983). A floating form without radiating pseudopodia is typical for Platyamoeba but it is also known for some Vannella spp. (Page 1980, 1983). The establishment of a new genus based only on the structure of the cell coat (which is not even clear in all details) is not warranted. Thus, by now it is most reasonable to classify this species in the genus Vannella. (ref. ID; 4882)
Known habitat: Marine, upper layer of anaerobic sediments, in and beneath mats of colourless sulphur bacteria. Niva Bay, the Sound (15 km South from Helsingor), Denmark. (ref. ID; 4882)
Type slides; Deposited at the British Museum of Natural History (holotype 1995:9:6:3; paratype 1995:9:6:4). (ref. ID; 4882)
Vannella platypodia (Glaser, 1912) (ref. ID; 2093, 2359)
Description; Fresh water species. Its glycocalyx consists of a basal layer approximately 18 nm thick and, rising above that layer, two sorts of structures. Arranged in closely set rows are structures which Page et al. shall call glycostyles, since they are much more complex than simple filaments but are not separable from the surface as are the scales of some protozoa, including the amoebae Paramoeba eilhardi Schaudinn, 1896 and Mayorella riparia Page, 1972. A glycostyle is set on a pentagonal base approximately 65 nm in diameter, and rises to a height of about 110 nm above the basal layer. From its base to the narrowest point, it consists of five flat wings arranged about a central tubule, or united medially to form that tubule. The base is the broadest point of the entire structure, and each wing articulates with an angle of the pentagonal base, bifurcating just before reaching the corner. The narrowest point of the glycostyle, with a diameter of an about 12 nm, is located approximately five-eighths of its length from base to tip. The wall looks thickest at this point, where the greatly narrowed wings are essentially incorporated into the tubule. Distal to this neck, the structure flares, with a pentagonal cross-section into which the wings are partly incorporated as ribs, to a funnel-like end 24 nm or less in diameter. Chromium-shadowed preparations are in agreement with this structure. Before the tubular structure of the glycostyle was understood, it was thought that the glycostyle wings were filaments crossing to the opposite side at the narrowest point, but examination of a number of glycostyles in sections and in chromium-shadowed whole mounts demonstrates that this is not so. The appearance of crossing-over (if not an artifact of sectioning) may in some cases be due to a slight twisting of the glycostyle. No glycostyles were ever seen to be separated from the cell surface. (ref. ID; 2359)
Measurements; 10-25 um. (ref. ID; 2359)
Vannella simplex (Wohlfarth-Bottermann, 1960) (ref. ID; 2093, 2359)
Description; The basal layer of its glycocalyx is approximately 24 nm thick, and its glycostyles and simple filaments are indistinguishable from those of the much smaller V. platypodia. (ref. ID; 2359)
Measurements; 35-80 um. (ref. ID; 2359)