Charles Krebs wrote:Order Tracheliida. This order contains a single species, Trachelius ovum, which is defined by three apomorphies: (i) a club-shaped internal oral basket; (ii) a lateral fossa with specialized ciliature; and (iii) many scattered contractile vacuoles.
I'm usually hesitant to name a protozoan down to the species level... but we can certainly see the "fossa" and the "many scattered contractile vacuoles" in the last three photos... Trachelius ovum
Ah, well, about that...there are now 2 genera in Tracheliida, and each contains a single species, and, I'm sorry to say, they are fairly difficult to tell apart!
In their Monograph of the Diliptids (published a year after the excerpt you quoted), Peter Vdacny and Wilhelm Foissner proposed a new Tracheliid called Apotrachelius. It's a dead ringer for Trachelius, but instead of two big macronuclei, it has numerous small ones. I'm not sure whether the large ovals bodies in your critter are macronuclei or food... 
