world of amoeboid organisms

Difflugia ovata
Difflugia ovata, after Wang et Nie, 1933

Difflugia ovata  Wang et Nie, 1933

Diagnosis: Shell oval in shape, widest at the middle region, slightly narrower posteriorly than anteriorly, with an evenly rounded fundus; composed of a thin, transparent, and brownish chitinous membrane, with an incrustation of angular or amorphous scales or grains of quartz-sand or both of these. Aperture very large in proportion to the size of the test, four or five sided, with some of the corners more or less deeply notched or indented. Protoplasmic body colourless and trans¬parent, occupying a greater portion of the cavity of the test, connected to the fundus of the test by several protoplasmic threads, containing chlorophyllous food particles. Nucleus spherical, posteriorly located. Pseudopodia very few, long and thick, bluntly rounded at their free ends.

Dimensions: Length 50-60 um, width 30-40 µm.

Ecology: Freswater lake, China

Remarks: ‘The occurrence of this new species is rather rare and only few individuals were observed among the Sphagnum and sub¬merged vegetation from a water sample collected from the Lake Ho Hu during the first part of May, 1933.
Difflugia ovata may be distinguished from other known species of the genus by its oval and comparatively small test which possesses an irregularly square or pentagonal terminal mouth. In one observed specimen, the chitinous test is covered only with angular siliceous platelets which are rather uniform in size and very approximately paved together. The test in this case appears semi-transparent and very smooth in
outline. The chitinous test in other specimens is incorpor¬ated with either a mixture of siliceous scales and grains of quartz-sand or the latter alone. Thus the test appears less smooth and more opaque than the preceding one and the brown¬ish colour of the chitinous membrane becomes obscured from examination due to the presence of dark sand grains.
Although the mouth of the test is described as four or five sided, it appears rather irregular in outline since one or more notches or indenta¬tions are usually formed at the angles of adjacent sides. Sometimes the in¬dentations are so deep that, in the lateral view, the bord¬ers of the mouth appears as to be lobate. It is probably that, due to the thinness and elasticity of the chitinous membrane, the mouth of the test is more or less able to extend and retract and, as a consequence, the outline of the mouth may be slightly modified from time to time.'(Wang and Nie, 1933)

Ferry Siemensma, created January 25, 2024; last modified January 25, 2024
Recent posts