Nadinella tenella, pseudostome

 

 

Nadinella tenella Penard, 1900

 

I found this single specimen in the river Saar near Saarburg, Germany, in sediment on submerged stones along its shore. It differs from the shell found in the Netherlands in having a narrower pseudostome, where the Dutch species has a broad oval one.

 

Pseudostome and collar, with two filopodia
Nadinella tenella, with arrowed collar and pseudostome with 5 filopodia
Plasm visible; it doesn't fill the shell completely