Paramphitrema lemanense (Penard, 1903)
Diagnosis: Shell elliptical, in cross section compressed or circular, with two apertures at opposite poles, more or less ending in two tubes. Shell covered with small mineral particles. Two types of filopodia, either thin and branching or thicker with only one per pseudostome during rapid locomotion. Plasma fills the shell completely.
Dimensions: Penard 20-35 µm; my measurements 24-44 µm (n=9). De Groot (1979) observed in one sample 10 very active specimens with a somewhat slender shell, 33-36 µm long.
Ecology: Clear fresh (running) water. De Groot (1979) found his specimens in a small clear spring near the city of Arnhem in the Netherlands. I found my specimens in detritus from the Neerbeek (in Neer, 2011), a small river in the southern part of the Netherlands, in floating detritus and sediments of a ditch in the nature reserve Naardermeer (2012 and 2013) and in the river Weser near Oberwerner, Germany (2012).
Remarks: I have seen nine specimens. They were moving fast, with the anterior part of the shell a little tilted. Therefore it was impossible to get both filopodia at the same moment visible at the photomicrograph. Here is a drawing a big advantage, see below.
This species is probably identical with P. rhenanum, see the remarks there.
Further investigations are needed to clear its taxonomic status. In its behaviour and the presence of flagella-like filopodia with thickened base, this species closely resembles Artodiscus saltans.