Difflugia longum – Microworld

D. longum – a from Chardez, 1985; b-c. from Chardez, 1987; Shell a was originally included by Chardez (1985) in his description of D. acutissimella, that he had found in the same lake as the other tests.

Difflugia longum Chardez, 1987

Diagnosis: Shell very elongated, circular in cross-section, terminally acute, sometimes slightly curved on the side; most bulging part of the test is always around the anterior third; pseudostome circular, preceded by a very short, more or less pronounced neck, which is always present. Shell embedded with flat, polymorph mineral platelets, which are smaller towards the aperture; lobed pseudopodia are broad; cytoplasm clear; nucleus spherical

Dimensions: Chardez (1987): Shell length 256-280 μm; width 75-86 μm; pseudostomal diameter 44-47 μm; neck height 3-7 μm; nucleus 28-30 μm. My measurements: height 247-298 μm; L/B=2.19-3.97 (n=14). According to the three pictures made by Chardez, L/B=2.65-3.41.

Ecology, Freshwater; sediment of lakes and ditches (Lake Virelles, Belgium, 1987; Naardermeer, Netherlands 2017, 2019).

Remarks, in the population of the Naardermeer I found occasionally tests with two spines. Vucetich (1987) has described the two-spined D. diafana. I think that this species is synonymous to D. longum.

Literature, Chardez, D., 1987. Contribution à la connaissance des Thécamoebiens des dépôts lacustres – Acta Protozool., 26: 1, 59-62