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The World of Protozoa, Rotifera, Nematoda and Oligochaeta


Ochromonas Vysotskii, 1887 (ref. ID; 5772), Wyssotzki (ref. ID; 1618) or Wysotzki (ref. ID; 3490)

Straminopiles: Chromulinales Pascher, 1912 (= Chromomonadina Klebs, 1893) (ref. ID; 5772)

[ref. ID; 1618]
Solitary or colonial; body surface delicate; posterior end often drawn out for attachment; 1-2 chromatophores usually with a stigma; encystment; fresh water. See Monas. (ref. ID; 1618)

[ref. ID; 3490]
The cell is always solitary and naked to change easily to an amoeboid form and has one or two chromatophore, a contractile vacuole and sometimes an eye-spot. (ref. ID; 3490)

[ref. ID; 3720]
Some 80 spp. of Ochromonas have now been described (Rieth 1967, 1970) but studies with the electron microscope have been made on only few. (ref. ID; 3720)

[ref. ID; 4377]
The chrysophyte genus Ochromonas, which combined both plant- and animal-like characters, is potentially interesting for a number of biochemical and physiological characteristics: (a) it requires vitamin B12 and synthesizes only negligible quantities of chlorophyll-c (Aaronson 1980); (b) its short flagellum contains an autofluorescent green pigments (Coleman 1988); and (c) its cell body contains vesicles capable of exocytosis upon light stimulation (Coleman 1986). (ref. ID; 4377)
  1. Ochromonas angulosa Skuja (ref. ID; 4840)
  2. Ochromonas danica Pringsheim, 1955 (ref. ID; 3806) reported year? (ref. ID; 3720, 4949) reported author and year? (ref. ID; 4377)
  3. Ochromonas globosa Skuja, 1956 (ref. ID; 4790)
  4. Ochromonas granularis Doflein (ref. ID; 1618)
  5. Ochromonas ludibunda Pascher (ref. ID; 1618)
  6. Ochromonas malhamensis Pringsheim (ref. ID; 3908, 4949) reported author and year? (ref. ID; 3806)
  7. Ochromonas minuta Pringsheim (ref. ID; 4949) reported author and year? (ref. ID; 4377)
  8. Ochromonas monicis Doddema & Veer (ref. ID; 4840)
  9. Ochromonas mutabilis Klebs (ref. ID; 1618, 3490)
  10. Ochromonas simplex Pascher? (ref. ID; 3494)
  11. Ochromonas sociabilis Pringsheim (ref. ID; 4949) reported author and year? (ref. ID; 3806)
  12. Ochromonas sphaerocystis Matvienko (ref. ID; 4840)
  13. Ochromonas tuberculatus (ref. ID; 4790)
  14. Ochromonas villosa Clarke & Pennick, 1981 (ref. ID; 3720 original paper)
  15. Ochromonas vulcaia (ref. ID; 4840)
  16. Ochromonas vulcanus (ref. ID; 4790)

Ochromonas danica Pringsheim, 1955 (ref. ID; 3806) reported year? (ref. ID; 3720, 4949) reported author and year? (ref. ID; 4377)


Ochromonas globosa Skuja, 1956 (ref. ID; 4790)


The cell body of O. globosa is ovoid or nearly globular, 5-13x5-10 um, not pyriform as the O. danica cell. Metaboly and tail were not observed. The beak, characteristic of O. danica is here absent, but the platform is visible on the anterior end of the cell. O. globosa has two flagella -a long one, the anterior provided with mastigonemes, the first flagellum "F", and a short one, smooth, directed sideward, the second flagellum "S". The first and the second basal bodies correspond to "F" and "S" flagella. The "F" flagellum is twice as long as the cell body, the "S" one is only about 2 um long, and is hardly visible under the light microscope. (ref. ID; 4790)

Ochromonas granularis< Doflein (ref. ID; 1618)


No stigma. (ref. ID; 1618)


5-12 um long. (ref. ID; 1618)

Ochromonas ludibunda Pascher (ref. ID; 1618)


Not plastic. (ref. ID; 1618)


12-17 by 6-12 um. (ref. ID; 1618)

Ochromonas mutabilis Klebs (ref. ID; 1618, 3490)


Ovoid to spherical; plastic. (ref. ID; 1618)
The small species is fusiform, somewhat tapering in the posterior end and contains two chromatophores and a rather large contractile vacuole. (ref. ID; 3490)


15-30 by 8-22 um. (ref. ID; 1618)
Length 15-20 um. (ref. ID; 3490)

Ochromonas villosa Clarke & Pennick, 1981 (ref. ID; 3720 original paper)


Cells spherical, ovoid or elongate, 2.5-6 um long x 1.75-3.5 um wide, strongly metabolic, with a pale gold-coloured chloroplast and two flagella, 7.5 and 2 um in length respectively, the longer bearing two rows of mastigonemes. Both flagella and body completely covered with fine appendages 1.8-3 um in length, visible only with the electron microscope. Cysts slightly flattened spheres, diameter 3.5-6 um, with plugged pore diameter 0.75-1.2 um flush with cysts surface, nutrition holophytic. (ref. ID; 3720)


Under the light microscope cells may appear spherical, ovoid, or elongate and in hanging drop preparations the proportion of spherical cells to those of other shapes is approximately 2:1. Cell size ranges from 2.5-6 um in length and from 1.75-2.75 um in width. Elongate cells travel in a straight path with the two flagella directed forwards, while ovoid and spherical ones swim in a slower, helical path. When cells of any shape come to rest, they rotate, commonly in a clockwise direction. The centre of rotations is about a point towards the posterior of the cell. Healthy, rotating cells in hanging drop preparations were observed to change shape from elongate to spherical. From coming to rest, the approximate time taken for this change was 5 min. Each cell contains a chloroplast of pale gold colour, towards the anterior end. An eyespot is present near the flagella bases. A large vesicle occupies the posterior portion of the cell. Observations on living cells in dilute Indian Ink under the light microscope showed them to be surrounded by a transparent sphere approximately twice the cell diameter. This transparent sphere did not stain with methylene blue, eosin, cresyl blue or ruthenium red. Alcian blue caused slight staining of flagella and cell surface showing the presence of polysaccharide, indicating mucilage. Examination of shadowcast or stained whole cell preparations with the electron microscope shows the cell to be covered with a dense integument of fibrous appendages, 1.8-3 um in length and about 4 nm wide. These appendages are borne with equal density over the whole surface of the body and on both the long and the short flagella. This integument is the "transparent sphere" observed with the light microscope as described above. In addition to the fibrous appendages, the long flagellum bears two opposite rows of mastigonemes. In one row the single units are spaced at regular intervals along the flagellar length; in the opposite row they are arranged in groups of 4 or 5 proximally and of 2 or 3 distally. Individual mastigonemes are 1 um long and 0.02 um wide. Each bears fine lateral hairs approximately 20 nm in length and 2 terminal hairs 400 nm in length. O. villosa, therefore, has four types of appendage: (i) Fibrous appendages on the body surface and on the axes of both flagella. (ii) Tubular mastigonemes on the long flagellum. (iii) Fine lateral hairs borne on (ii). (iv) Fine terminal hairs borne on (ii). (ref. ID; 3720)
  • Cyst: Cysts were observed when examining ageing cultures by light microscopy. These are smooth, slightly flattened spheres 3.5-6 um in diameter. A plugged pore 0.75 to 1.2 um in diameter is positioned in the centre of one of the flattened surfaces. (ref. ID; 3720)


    The external morphology of O. villosa accords with the characteristics of the genus as defined by Bourrelly (1957). The fibrous investment of the body of O. villosa appears to be unique among the species so far described and the occurrence of the same fibres on both the body and flagella is of particular interest. These appendages invite comparison with the fibrous mastigonemes first described by Bouck (1971, 1972) on both flagella of Ochromonas danica Pringsheim, Chlamydomonas reinhardii Dangeard, Cyanophora paradoxa Korschikov and Pavlova sp. (ref. ID; 3720)

    Type material

    Type material from No. LB 933/25 in the CCAP collection, originating from a collection by the late R.W. Butcher from a saline ditch at Bembridge, Isle of Wight, England, June, 1959. (ref. ID; 3720)