D. longum - a from Chardez, 1985; b-c: from Chardez, 1987; Test 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: Test 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. Test embedded with flat, polymorph mineral platelets, which are smaller towards the aperture; lobed pseudopodia are broad; cytoplasm clear; nucleus spherical

 

Dimensions: Chardez, 1987: Height 256-280 μm, diameter 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 the L/B=2.65-3.41.

 

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

 

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.: Contribution à la connaissance des Thécamoebiens des dépôts lacustres - Acta Protozool. 26: 1, 59-62 (1987)

 

 

D. longum, Naardermeer, the Netherlands. All tests c. 260 μm (247-298 μm). Notice the two-spined tests.