world of amoeboid organisms

Menu
Difflugia acuminata
Difflugia acuminata: left to right: 293 µm, 330 µm, 333 µm (drawing after Ehrenberg, 1838)

Difflugia acuminata Ehrenberg, 1838

Diagnosis: shell long, cylindrical, slightly tapering from the posterior to the anterior end; posterior end pointed or with a more or less long, hollow and open tube or spine; shell composed of mineral grains, more or less mixed with scales of diatoms; in sphagnum the test can be completely composed of diatoms; aperture circular.

Dimensions: In his original description Ehrenberg gives a length of 1/3 mm = 333 µm. He describes the test as being oval oblong (see his drawing above).
The late Dr. A.A. de Groot (pers. comm.) has found shells in Baarn, the Netherlands, which were 800 µm large!

Ecology: Freshwater, all kind of water types, ranging from oligotrophic till eutrophic.

Remarks: Difflugia acuminata is probably a polymorphic species. Without doubt several variations of Difflugia acuminata has been described as new species. On the other hand the name covers probably several real species which are light microscopically hard to distinguish from the main morphotype. The most discriminating character is the shape en length of the spine, but in fact we don’t know precisely how variable it is. Shells with relatively long spines have been described as Difflugia giganteacuminata and with a curved spine as Difflugia curvicaulis.

Difflugia acuminata
Shells of Difflugia acuminata differ in shape, structure and size (180-390 µm)
Difflugia acuminata
Shells in a sample from Lemmer, Friesland, ranging from 204-429 µm. It shows the variability of this species.
Difflugia acuminata
These shells came from one sample (Kortenhoef) and varied in size from 214-364 µm. The first five specimen seems closely related, the other two tests are different.
 Difflugia acuminata
These shells came from another sample (Strabrechtste heide, Eindhoven), ranging from 239-322 µm.
Difflugia acuminata
Shells from a sample from Lemmer, Friesland, ranging from 180-253 µm
Five shells from the same sample, from Crailoo, measuring 270 to 415 µm
Recent posts

Spiculophrys

Genus Spiculophrys Zlatogursky, 2016 Diagnosis: Centrohelids lacking silica scales but with numerous thin, pointed organic (without any traces of silica) scales tapering towards acute apices. 18S

Read More »

Acanthocystis drakena

From Zlatogursky, 2016 Acanthocystis drakena Zlatogursky, 2016 Diagnosis: Cells are 21.1-30.5 µm (ca. 26.7) in diameter. Cell is covered with oval plate-scales having a margin

Read More »

Choanocystis symna

From Zlatogursky, 2014 Choanocystis symna Zlatogursky, 2014 Diagnosis: Cell body ca. 6.7 µm in diameter. Axopodia three–five times longer than a cell diameter. Plate-scales dumbbell-shaped

Read More »

Acanthocystis costata

From Zlatogursky, 2014 Acanthocystis costata Zlatogursky, 2014 Diagnosis: Cell body ca 9.5 µm in diameter. Axopodia 2–3 times longer than cell diameter. Length of spine-scales

Read More »

Kinetocyst

Left: ultra-structure of a kinetocyst of Raphidiophrys contractilis); right: two kinetocysts in an axopodium. Kinetocysts In centrohelid heliozoa, extrusomes are called kinetocysts, and are present

Read More »

Yogsothoth carteri

Yogsothoth carteri, after Shishkin and Zlatogursky, 2018 Yogsothoth carteri Shishkin and Zlatogursky, 2018 Diagnosis: Individual cells in a colony have a diameter of 9.7-15.2 µm;

Read More »