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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Corythion

Corythion Taranek, 1881 (ref. ID; 3686)

Quote from ref. ID; 3536

Rhizipoda (ref. ID; 2032)

[ref. ID; 1618]
Test small, hyaline, composed of small oval siliceous plates; compressed; elliptical in cross-section; aperture subterminal, ventral or oblique, and circular or oval; numerous filopodia; fresh water. (ref. ID; 1618)

[ref. ID; 3686]
Shell colourless; ovoid, oval in transverse section; composed of small oval shell-plates; aperture oval, invaginated and bordered by small denticulate, apertural-plates. (ref. ID; 3686)
  1. Corythion aerophila Decloitre, 1950 (ref. ID; 2509)
  2. Corythion asperulum Schonborn, 1988 (ref. ID; 2032 original paper)
  3. Corythion delamarei Bonnet & Thomas, 1960 (ref. ID; 2054, 2466 original paper, 4860, 5461) reported year? (ref. ID; 3383)
  4. Corythion dubium Taranek, 1871 (ref. ID; 2032), 1881 (ref. ID; 2509, 3686, 4737, 4755, 5461, 7609) or 1882 (ref. ID; 661, 2099, 2147, 2441) reported year? (ref. ID; 2233, 2235, 2329, 2330, 2456, 3223, 3491, 3501, 3598, 3693) reported author and year? (ref. ID; 6795)
  5. Corythion dubium var. aerophila Decloitre, 1950 (ref. ID; 2110, 2420, 4860)
  6. Corythion dubium var. orbicularis Penard, 1910 (ref. ID; 5461) reported year? (ref. ID; 2147)
  7. Corythion dubium var. spicatum Penard, 1910 (ref. ID; 2032)
  8. Corythion dubium var. terricola Schonborn, 1964 (ref. ID; 2054) reported year? (ref. ID; 3383)
  9. Corythion nebeloides Bonnet, 1960 (ref. ID; 3537 original paper) reported year? (ref. ID; 2090, 3383, 3539)
  10. Corythion pulchellum Penard, 1890 (ref. ID; 661, 1618, 2099, 2235, 2329, 2330, 2420, 2466, 5461) reported year? (ref. ID; 3491, 3693)
  11. Corythion renistoma Decloitre (ref. ID; 2584 original paper)

Corythion asperulum Schonborn, 1988 (ref. ID; 2032 original paper)

Diagnosis

Shell ovoid in dorsal view, dorso-ventrally compressed; aperture nearly semicircular, slightly invaginated, with a row of teeth. Idiosomes consist of elongate oval plates, irregularly placed on the shell. The shell has a variable number of tiny spines, distributed over the whole surface. The spines protrude singly from the junctions of the plates. Idiosomes and spines essentially consist of silicium. Shells colourless and usually transparent. Nucleus with a slightly eccentric nucleolus. (ref. ID; 2032)

Comments

This species is closely related to C. dubium. Both species occurred together in the needle layer of spruce forest soils. Pseudopodia could not be observed, but food-bundles surrounding the aperture are seen. The species is not identical with Corythion dubium var. spicatum Penard, 1910. Contrary to C. asperulum the spines of var. spicatum are longer, in a single row and consist of chitin. This curious form had been found only twice (Penard 1910, Vol.I, Plate XXII, Fig.3b; Heinis 1914). (ref. ID; 2032)

Type locality

Spruce foreset soil at Plothen (GDR, Thuringia). (ref. ID; 2032)

Measurements

Shell length 31.2-43.7 (average 42.3); width 31.2-43.7 (average 34.6); height 17.5-21.9 (average 18.8 um). (ref. ID; 2032)

Corythion delamarei Bonnet & Thomas, 1960 (ref. ID; 2054, 2466 original paper, 4860, 5461) reported year? (ref. ID; 3383)

Descriptions

Typical soil-inhabiting species. Small elliptical shell covered with oval plates, translucent, colourless. (ref. ID; 4860)

Measurements

Length of the shell 19-25 (22+/-3), width of the shell 11-14 (12.5+/-1.5), height of the shell 7-9 (8+/-1), aperture of the shell 1.5-3 (2.2+/-0.8) um (n=56). (ref. ID; 4860)

Corythion dubium Taranek, 1871 (ref. ID; 2032), 1881 (ref. ID; 2509, 3686, 4737, 4755, 5461, 7609) or 1882 (ref. ID; 661, 2099, 2147, 2441) reported year? (ref. ID; 2233, 2235, 2329, 2330, 2456, 3223, 3491, 3501, 3598, 3693) reported author and year? (ref. ID; 6795)

Descriptions

The shell is ovoid and composed of approximately four hundred oval shell-plates. The shell-plates usually overlap, and are often arranged haphazardly so that many are either incompletely or completely covered. The aperture is sub-terminal, oval and invaginated. About thirty small, oval, apertural-plates surround the aperture and each carries a median dorsal tooth. These apertural-plates are similar to those seen in Trinema enchelys and T. lineare. Differences in the size of the shell are illustrated by Cash et al., (1915). (ref. ID; 3686)
Shell ovoid, flattened. Idiosomes oval, irregularly arranged. Aperture sub-terminal, circular to oval, invaginated. Apertural plates with a median tooth. (ref. ID; 4755)

[ref. ID; 7609]
Culture strain: Locomotion and feeding by the extension of fine tapering filopodia, often up to 80 um length, were observed in active specimens. Movement was extremely slow; viewed with a binocular stereo-microscope an animal's activity is revealed only by intermittent "jerky" movements of the whole test. These are apparently caused by the recoil resulting from the sudden relaxation of tension in filopodia after application of leverage on the substrate, to which amoebae strongly adhere. The normal position of active, feeding individuals is with the aperture facing downwards so that the test is appoximately parallel to the substrate surface. Limited observations of binary fission were made on dividing pairs of amoebae in hanging-drop preparations. Construction of the daughter test was relatively rapid, and normally completed in 10-15 min, with cytoplasmic division and transfer from parent to daughter being accomplished after 1 hr or less. Rapid cytoplasmic streaming, together with the movement of large numbers of small vacuoles was observed during most of this period. Separation of daughter from parent was proceded by sideways rocking movements during which short filopodia could often be seen protruding from the junction of the two opposed apertures. Compelte separation occurred in one instance only 14 min after the cessation of cytoplasmic transfer. These observations indicate that the total division process in C. dubium occupies 1-2 hr. Immediately after separation, both parent and daughter tests were incompletely filled with cytoplasm, and the newly acquired contents of the daughter shell in particular often appeared to be anchored at specific points within the aboral region of the test, giving the cell envelope a characteristically angular outline. For some time afterwards, the cytoplasm of both separated amoebae then appeared to be lighter or less dense in colour than that of older amoebe. These phenomena were clearly visible, and were repeatedly observed; where apparent in two individuals in close proximity in culture this can be taken as reliable evidence of a recent division. Scanning electron micrographs of tests of cultured specimens revealed the usual imbricated arrangement of between 300 and 450 rounded rectangular shell plates that comprise the ovoid test (Decloitre 1960; Mercier et al. 1964), together with 30-40 toothed shell plates that surround the invaginated aperture. In some specimens, the apertural lip was slightly more prominent than usual, which may have been a culture-induced characteristic. (ref. ID; 7609)
  • Aberrant forms. Variants were occasionally observed in Corythion cultures and were most often represented by individuals with two apertures at opposite poles of an enlarged test. Cell lysis eventually occurred in the few cases observed where the test contained cytoplasm, and none were ever seen to attempt division. In one particular culture, however, a large number of distorted tests were evident. Most commonly encountered was a form, again with an extra aperture, but in this case with both in an adjacent position at the same pole of the test. Observations of one such live specimen revealed normal locomotion and feeding, although only one of the apertures was being utilised. More remarkably, some of these abnormal individuals were seen to undergo successful division in the usual manner, so that the identical daughter test produced by the parent inherited the extra aperture. By transferring dividing pairs of amoebae of fresh media, it was eventually possible to establish a clonal subculture line, consisting entirely of these double-aperture forms, which was maintained separately. The cultured amoebae of subsequent generations were then observed to use both apertures for normal activity, the test being completely filled with cytoplasm, and containing a single nucleus. In most respects, their behaviour was similar to that of normal Corythion, although growth was slower, and division occasionally resulted in single-aperture specimen, the daughter test being constructed in opposition to only one of the aperture. The test of the double-aperture form, compared to normal Corythion, is only slightly longer, although its width is enlarged by 5-10 um, giving the whole a more rounded appearance. Scanning electron micrographs revealed that the total number of apertural teeth was no greater than normal, these being distributed (in some cases unevenly) between the two smaller apertures. The shell-plate dimensions of both normal and aberrant forms were the same. (ref. ID; 7609)

    Measurements

    Length 40; breadth 25; mouth 10 um. (ref. ID; 2233)
    Shell length 33-55, width 24-33; diameter of aperture 9-17; shell-plates length 2.9-3.4, width 1.5-1.9; diameter of apertural-plates 0.9-1.1 um (n=3). (ref. ID; 3686)

    Corythion dubium var. aerophila Decloitre, 1950 (ref. ID; 2110, 2420, 4860)

    Descriptions

    This species lives in aerophytical mosses. Shell flat, often concave, from ventral view practically circular, translucent, colorless. Shell surface covered with small elliptical plates. Aperture circular or semicircular with a fine denticular rim. (ref. ID; 4860)

    Measurements

    Length of the shell 23-27 (25+/-2), width of the shell 20-25 (22.5+/-2.5), height of the shell 3-6 (4.5+/-1.5), aperture of the shell 6-9 (7.5+/-1.5) um (n=7). (ref. ID; 4860)

    Corythion pulchellum Penard, 1890 (ref. ID; 661, 1618, 2099, 2235, 2329, 2330, 2420, 2466, 5461) reported year? (ref. ID; 3491, 3693)

    Descriptions

    Aperture lenticular; cytoplasm colorless; two to three contractile vacuoles. (ref. ID; 1618)

    Measurements

    25-35 by 15-20 um; aperture 7-10 by 3-4 um. (ref. ID; 1618)