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Massisteria spec. fresh water - Ferry Siemensma
Microcometes spec., arrow indicates the two cilia; fresh water – Laegieskamp, The Netherlands

Microcometes spec.

Diagnosis: small body, usually under 7 µm, which in trophic organisms emits curving, sometimes branched fine pseudopodia with extrusomes, and have two cilia lying inactive over the body surface. Trophont does not move actively, feeds usually on bacteria. Cell covered by a tiny shell which is often hard to detect.

Remarks: I found several specimens in wet-chamber-mounts from samples from the Laegieskamp, The Netherlands. At first I thought it was a fresh water Massisteria-species, but most specimens had a kind of shell or an indication of a shell (see all photomicrographs on this page). This shell was not so distinct and well developed as in common Microcometes palludosa specimens, where the shell wall is rather thick and usually yellow to brown when aging and never have more than five apertures. The specimens described here seem to live inside a kind of shell which is hard to detect light microscopically and is usually colorless. It has 4-7 apertures, if these are apertures like those in M. palludosa.

Massisteria spec. fresh water - Ferry Siemensma
Microcometes spec., arrows indicate the two cilia; the cell is probably surrounded by a kind of shell.
Massisteria spec. fresh water - Ferry Siemensma
Microcometes spec., the arrow indicates the two cilia
Massisteria spec. fresh water - Ferry Siemensma
Microcometes spec., arrows indicate the two cilia; the cell seems to be inside a kind of shell.
Below four photomicrographs of the same cell:
Microcometes spec - Ferry Siemensma
Microcometes - Ferry Siemensma
Microcometes, with two cilia (see arrows)
Microcometes - Ferry Siemensma
Microcometes - Ferry Siemensma
The same cell as above, in phase contrast (left hand) and normal illumination. This shell is less obscure as in other specimens.
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