Main Content
< Top page

The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Pleuretra

Pleuretra Bryce, 1910

ref. ID; 1663

With a well-developed rostrum and corona, the latter always capable of being retracted into the mouth. With four plain toes of which two are dorsal and two terminal. Cuticle leathery, with many transverse folds. Stomach with a true lumen. Intestine ciliated. Oviparous. In mosses. (ref. ID; 1663)

ref. ID; 1923

Spurs shorter. (ref. ID; 1923)

ref. ID; 3137

The cuticle is unusually stiff and it forms a layer which is very similar to the armour of the Rotifera Monogononta; it is called half-armour by Remane. On the ventral side of the trunk the cuticular folds form transversal ventral ridges. The number of the ventral ridges exceeds the number of the false trunk-segments. The eye-spots are always lacking. The foot ends in four toes. Oviparous. D.f.: takes usually 2/2. (ref. ID; 3137)
  1. Pleuretra alpium (Ehrenberg, 1853) (ref. ID; 1345, 2757, 3137, 3523, 3688)
    Syn; Callidina alpium Ehrenberg, 1853 (ref. ID; 1345, 2276, 2757, 3137, 3688); Philodina alpium Murray, 1905 (ref. ID; 1345, 3137, 3688); Pleuretra alpium Bryce, 1910 (ref. ID; 1345, 3137, 3688)
  2. Pleuretra bovicornis Bartos, 1962 (ref. ID; 2731 original paper)
  3. Pleuretra brycei (Weber, 1898) (ref. ID; 1345, 1923, 3137, 3508, 3523, 3688) reported year? (ref. ID; 7857)
    Syn; Callidina brycei Weber, 1898 (ref. ID; 1345, 2276, 3137, 3511, 3523, 3688); Callidina brycei var. spinosa Thiebaud, 1911 (ref. ID; 1345, 3511); Callidina cataracta Lord, 1898 (ref. ID; 1345, 3137, 3511, 3688); Macrotrachela brycei Bartos, 1938 (ref. ID; 3688); Philodina brycei Murray, 1905 (ref. ID; 1345, 3137, 3511, 3688); Pleuretra brycei Bryce, 1910 (ref. ID; 1345, 3137)
  4. Pleuretra costata (Bartos, 1938) (ref. ID; 1345, 3137, 3688)
    Syn; Macrotrachela costata Bartos, 1938 (ref. ID; 1345, 3137, 3688)
  5. Pleuretra humerosa (Murray, 1905) (ref. ID; 1345, 2757, 3144, 3688)
    Syn; Philodina humerosa Murray, 1905 (ref. ID; 1345, 2757, 3688); Pleuretra humerosa Bryce, 1910 (ref. ID; 1345, 3688)
  6. Pleuretra hystrix Bartos, 1950 (ref. ID; 1345)
  7. Pleuretra intermedia Bartos, 1938 (ref. ID; 1345, 3137, 3688) reported year? (ref. ID; 3397, 7857)
    Syn; Mniobia intermedia Bartos, 1938 (ref. ID; 1345, 3137, 3688); Pleuretra intermedia Bartos, 1938 (ref. ID; 1345)
  8. Pleuretra lineata Donner, 1961 (ref. ID; 2686 original paper) or 1962 (ref. ID; 2275)
  9. Pleuretra proxima Bartos, 1962 (ref. ID; 2731 original paper)
  10. Pleuretra reticulata Milne, 1916 (ref. ID; 1345, 3137, 3688) reported author and year? (ref. ID; 2972)
  11. Pleuretra similis Bartos, 1962 (ref. ID; 2731 original paper)
  12. Pleuretra sulcata Bartos, 1950 (ref. ID; 1345, 3137) reported year? (ref. ID; 3688)
    Syn; Philodina americana Donner, 1950 (ref. ID; 1345) or 1951 (ref. ID; 3137)

Pleuretra alpium (Ehrenberg, 1853) (ref. ID; 1345, 2757, 3137, 3688)

Synonym

Callidina alpium Ehrenberg, 1853 (ref. ID; 1345, 2276, 2757, 3137, 3688); Philodina alpium Murray, 1905 (ref. ID; 1345, 3137, 3688); Pleuretra alpium Bryce, 1910 (ref. ID; 1345, 3137, 3688)

Descriptions

The light yellow and almost transparent body of this species is nearly 238 µm in length. The cuticle is very stiff, coarsely stippled but not sticky. On the surface of the trunk 14 longish cuticular folds and 9-10 transversal ridges on the ventral side of the trunk. The anterior border of the half-armour bears on the dorsal surface six blunt knobs and on the ventral surface two more knobs. The wheel-organ is much wider than the head, the wheel-discs are far apart. The anterior border of the upper lip is broad with shallow notch. The foot is short and four-jointed. The spurs are blunt conical and far apart. D.f.: 2/2. This species is somewhat variable in the number of its ventral ridges, in the quality of the cuticular surface of the body, and in the number of knobs on the anterior border of the half-armour. (ref. ID; 3137)

Comments

The Bohemina individuals have 10 ventral ridges on the trunk, several of these ridges are united with the lateral longish cuticular folds. Bryce records that Pleuretra alpium Ehrenberg is provided sometimes with the D.f.: 5/6. I discovered such individuals of this D.f.: but a close and more thorough examination of all these individuals showed that they were always individuals of Habrotrocha fusca Bryce with one extra-usually thin mucous cover. (ref. ID; 3137)

Pleuretra brycei (Weber, 1898) (ref. ID; 1345, 1923, 3137, 3508, 3523, 3688) reported year? (ref. ID; 7857)

Synonym

Callidina brycei Weber, 1898 (ref. ID; 1345, 2276, 3137, 3511, 3523, 3688); Callidina brycei var. spinosa Thiebaud, 1911 (ref. ID; 1345, 3511); Callidina cataracta Lord, 1898 (ref. ID; 1345, 3137, 3511, 3688); Macrotrachela brycei Bartos, 1938 (ref. ID; 3688); Philodina brycei Murray, 1905 (ref. ID; 1345, 3137, 3511, 3688); Pleuretra brycei Bryce, 1910 (ref. ID; 1345, 3137)

Descriptions

The body is grayish red to dark brown, and it attains a length of 350 to 400 µm. The cuticle of the trunk is coarsely granulated with deep longish cuticular folds and with strongly transversal ventral ridges on the ventral side of the trunk. The first transverse row of spines is on the anterior border of the half-armour, and the second transverse row is on the posterior border of the third false trunk segment. The wheel-organ is relatively wide. The sulcus is narrow. The rostrum is long and cylindrical. The dorsal antenna is long. The foot is short and stout. The spurs are long, conical too far apart. D.f.: 2/2. This species belongs to the very variable species of this order. Especially variable is the number of the spines in single transversal rows of spines, the number of the spines in these spine-rows, the length and stoutness of the spines, and finally the shape, the stoutness and the length of the inner spines of the first transversal row are variable. Several individuals captured in the damp rock-mosses of Jarov near Prague have unusually long spines in the second transversal row on the trunk. (ref. ID; 3137)

Pleuretra costata (Bartos, 1938) (ref. ID; 1345, 3137, 3688)

Synonym

Macrotrachela costata Bartos, 1938 (ref. ID; 1345, 3137, 3688)

Descriptions

The light to dark grayish coloured body has a length of 250 to 280 µm. The cuticle of the trunk and of the foot is finely or coarsely granulated. The rostrum is short and broad with two small rostral lamellae. The dorsal antenna is short. The wheel-organ is not visible. On the anterior border of the dorsal side of the half armour are six pointed knobs and on the ventral side five. The longish cuticular folds on the dorsal side of the trunk form high, transparent keels, which fall into segments. At the beginning each segment of the keel forms a circular arch, in the middle it is deeply notched and the ends run out into large and strongly sicke-shaped teeth, which have the under notches sitting accurately into the arched parts of the following keel-segments. On the trunk are five rows of these ridge-keels. On the preanal and on the anal segments these keels are arranged pointing towards the interspaces between the spines of the trunk, but in the middle of these two segments they remain in the same position. On the anal segment only two side-spines on the both sides of the segment are preserved and in the middle of this segment only low remains of former keel-spines decorate the surface of the anal-segment. On the ventral side of the trunk the splitting into two of the keel-spines is very closely visible. On the ventral side of the trunk 9-10 transversal cuticular ridges strengthen the trunk cuticle. A large knob sits on the dorsal surface of the first foot-joint. The spurs are large, apart, and pointed. D.f.: 2/2. (ref. ID; 3137)

Pleuretra intermedia Bartos, 1938 (ref. ID; 1345, 3137, 3688) reported year? (ref. ID; 3397, 7857)

Synonym

Mniobia intermedia Bartos, 1938 (ref. ID; 1345, 3137, 3688); Pleuretra intermedia Bartos, 1938 (ref. ID; 1345)

Descriptions

The body is stout, and it is covered with a stiff cuticle, which is thick and stiff especially on the rump. The body is colourless, only the digestive tube is in older individuals yellowish brown. The head, neck, and foot are completely smooth and transparent. The surface of the whole trunk especially in the posterior part, is coarsely granulated and all of it is opaque, almost only very slightly translucent. The first 2/3 of the rump are very stiff and forms two plates, of which the dorsal plate is arched and the lateral one with the posterior border of this plate is notched five-times in all. The second plate is the ventral one; this plate is flat, and is not granulated on the surface. The cuticle which unites these two plates on the lateral sides is thinner, and thus these two plates form a kind of pocket, into which the last, much narrower 1/3 of the rump and the whole foot are retracted. The dorsal cuticular folds of the trunk are only weakly developed, the side-ridges are a little stronger than the central ridges. On the ventral side of the trunk are six transversal central ridges. The first of these transversal ridges is provided with a long extension which runs on either side backwards to the surface of the second trunk-segment. The rostrum is short and stout. The rostral lamellae are minute and sharply pointed. The dorsal antenna is widest at the base and is half as long as the neck is wide. The foot is short, stout, and four-jointed. On the first 1/3 of the first foot-jointed there are on the dorsal surface two sharply pointed, but at the base wide and far apart hypodermal tubercles, which can be extended upwards or laid backwards on the surface of the joint. These tubercles are not always extended as is the case with Macrotrachela quadricornifera Milne or M. quadricorniferoides Bryce. The spurs have a very characteristic shape. They are little longer than the width of the segment to which they are fixed. Their outer border is very moderately arched, and they run parallel, directly backwards. The inner borders are very deeply notched in S-shape, and in such a way, that the connecting part of the notches is perpendicular to the body axis. The base of the spurs is very wide and the spurs are close together. There are four toes. The low pair of toes consists of two very far apart and backwards pointing toes. The upper toes are joined together so far as the tips, and these sit slightly apart from each other. The wheel-organ is only a little wider than the head. The sulcus is wide, and it is relatively shallow. The bridge is very distinct and smooth. The wheel-discs are without sensitive setae and papillae. The collar is powerfully developed, and it forms at the inner borders of the wheel-pedicels the short retractors of the wheel-discs. The upper lip is bowshaped and in the middle it runs out into a wide and straight cut-off middle lobe. D.f.: 2/2 with a third thin tooth on each jaw of all individuals seen. (ref. ID; 3137)

Measurements

The length of the body is 300 to 350 µm. (ref. ID; 3137)

Pleuretra lineata Donner, 1961 (ref. ID; 2686 original paper) or 1962 (ref. ID; 2275)

Descriptions

The rostrum was rather long but not unduly so, the lamella small with very slight notch, cilia long. The two-segmented dorsal antenna was slightly longer than the width of the neck and had on each side a small hump, visible both while creeping and feeding. The jaws were fairly long in proportion to their width but without any pronounced tapering, dental formula 2+1/2+1, teeth not very strong. The trunk at its last segment was narrowed, then swelled out to be about twice the width of the preanal segment which was twice the length of the anal segment. Foot of four segments, the first about twice the length of the second, spurs small and narrow, rather teat-like with rounded tips, the interspace about twice the width of a spur. Two dorsal toes small, two ventral only a little larger and fairly stout. The low arched upper lip with a slight notch reached to the level of the discs over a wide sulcus. The discs were slightly wider than the head and bore large conical papillae with sensitive setae. The feeding head was short, the neck segments were retracted into the trunk during feeding and made the feeding length much less than that while creeping. Quite a number of animals were found, giving ample opportunity to verify the slight differences from the description given by Donner (1965). (ref. ID; 2275)

Comments

Donner (1965) gives as a synonym Philodina americana Murray (1913) and probably P. americana Schulte (1954). The latter shows spurs very like those described here and Murray describes them as "nipple like but obtuse". In colour the trunk was a very pale brown but the granulation made it appear somewhat darker and greyish. Head and neck smooth and colourless, foot colourless but finely stipples. There were nine ventral folds and a cross section view showed twelve dorsal, all slightly raised from the surface, with the tips of each ridge showing oval shaped granules. (ref. ID; 2275)

Measurements

Length of creeping animal 200-212; length of feeding animal 135; width across the trochal discs 36; width across the head 32; head length 21; length of unci 15x7.5; length between the anterior edge of the discs and the mastax 33; length of spurs 6 µm. (ref. ID; 2275)

Pleuretra reticulata Milne, 1916 (ref. ID; 1345, 3137, 3688) reported author and year? (ref. ID; 2972)

Descriptions

The body is minute, widest in the middle of the trunk. The anterior border of the half-armour bears no spine. On the dorsal side of the trunk 5 transversal rows of small spines, on the posterior borders of the preanal and the anal segments transversal rows of somewhat larger spines. Besides these spines the ventral surface of the trunk has near its anterior border 7 ventral spines. The rostrum is provided with long lateral sensitive setae. The rostral lamellae are large and in the middle they are widely but shallowly deepened. The dorsal antenna is strong and is in length nearly 3/4 of the neck-width. The foot is four-jointed, it is small and on the first joint of it, a small dorsal granulated knob is visible. On the ventral surface of the trunk 9-10 ventral cuticular transversal ridges. The spurs are swollen at the base, close together and their surface is finely granulated, as is also the whole surface of the foot. The head and the neck are smooth. The wheel-organ is narrow. The sulcus is deep, narrow and the bottom of it is provided with a high and narrow bridge ligule. In the middle of the wheel-discs sits a long, to the body axis very transversally inclined sensitive seta. The upper lip is flatly arched and in the middle it is provided with a narrow and deep notch. The mouth-corners are very sharp and very protruding. Below the mouth-protuberances the very prominent lateral lobes of the lower lip are visible. D.f.: 2/2. (ref. ID; 3137)
  • Egg: The egg has on the whole of its surface several hemispherical knobs. The length of the egg is 65 to 74 µm, the width of it 34 to 40 µm. (ref. ID; 3137)

    Measurements

    The animal has a length of 250 µm. (ref. ID; 3137)

    Pleuretra sulcata Bartos, 1950 (ref. ID; 1345, 3137) reported year? (ref. ID; 3688)

    Synonym

    Philodina americana Donner, 1950 (ref. ID; 1345) or 1951 (ref. ID; 3137)

    Descriptions

    The vividly reddish coloured body is 300 to 350 µm long. The cuticle, especially on the trunk, is thick, coarsely granulated, but the surface of the head, neck, and foot with spurs is smooth. On the dorsal surface of the trunk are several longitudinal and broad folds. On the ventral side of the trunk 9 very well developed transversal ridges. The anterior dorsal margin of the trunk runs out into 6 large and semicircular knobs. On the ventral anterior margin of the trunk sit two much larger, but sharply pointed spines. From the tips of these spines longitudinal folds run backwards to the first and short transversal ridge. The ventral spines are separated by a straight and wide interspace. Rostrum is two-jointed. It bears two semicircular and separated rostral lamellae. The stiff, long tactile ciliae are well developed. The head propre is broad, with well distinct retracted wheel-discs. On the first neck-segment are two very large lateral knobs on either side of the base of the dorsal antenna. Dorsal antenna is long, two-jointed, and equals 1+1/2-1+3/4 of the diameter of the neck. The slender foot consists of four segments. On the third foot-segment are two long and slender conical spurs, which are sharply pointed. There are separated by a small interspace. This foot ends in two unequal pairs of toes. The upper pair of toes is much shorter and more slender than the lower one. The upper toes are very close together, the lower ones far apart. The broad wheel-organ is visible in the feeding action. It is much wider than the diameter of the head. The wheel-discs are far apart and they are separated by a broad and deep wheel-sulcus. On the surface of each wheel-disc sits a large sensitive papilla bearing a long tactile seta. The wheel-pedicels run backwards together. The collar forms on each wheel-pedicel a distinct basal borer, and passes into a semicircular wheel-retractor. The upper lip is arched, and it forms two median circular lobes. The lateral knobs of the first neck-segment form on the feeding head latero-posterior backwards pointing edges. D.f.: 2/2. (ref. ID; 3137)