I think that this is Litonotus rather than Loxodes because the cilia are most developed on the one side while Loxodes has more ciliae covering its entire surface. Loxodes has a concave mouth area, this specimen does not. I do not see any Mullers bodies in this specimen and usually Loxodes is brown in color rather than transparent.
I think it could be Litonotus. It has the two 'Circles' (Nuclei?) in it that show up in many other photographs. Definately doesn't have the hook in its nose that Loxodes has.
I observed this guy for about 15 minutes all told, and I never saw it extending its 'neck'. All of the other Litonotus examples I've seen seem to stretch out quite often.
I think I will classify it under Litonotus, unless someone comes up with a better ID.