Trachelomonas hexangulata (Svirenko, 1914)
Most likely ID: n.a.
Synonym: n.a.
Sampling location: Simmelried
Phylogenetic tree: Trachelomonas hexangulata
Diagnosis:
- lorica almost hexangular with parallel sides, anterior and posterior end conically shaped
- porus often with a narrowing ring
- length 25–34 µm, width 10–14 µm
- cylindrical collar, about 4 µm long
- lorica brownish or orange
- chloroplasts disc-shaped without pyrenoid
- one eyespot
- swims with posterior end first
I have only found a single specimen of Trachelomonas hexangulata in the Simmelried in August 2003. Before and after that I have not documented any finds, not even from my other sampling sites. Unfortunately, I only took one photo at that time (s. fig. 1). The characteristic shape of the lorica has the form of an elongated hexagon. Below the cylindrical collar, the narrowing ring can be seen from the side, which reduces the size of the porus opening (s. also left drawing above). Other Trachelomonas species do not show this special feature in the structure of the porus. In addition, Trachelomonas hexangulata stands out from the other species of the genus in that it swims backwards, i.e. with the conical posterior end first. Unfortunately, I was not able to observe this process myself because my specimen had already shed its flagellum under the cover glass.
Fig. 1: Trachelomonas hexangulata. L = 33 µm. Lateral view of an immobilized specimen that has shed its flagellum. Note the narrowing ring (NR) below the collar, which reduces the pore diameter. Obj. 100 X.