Sphenomonas angusta Skuja, 1956
Most likely ID: n.a.
Synonym: n.a.
Sampling location: Simmelried
Phylogenetic tree: Sphenomonas angusta
Diagnosis:
- cell rigid, elliptical or club-shaped
- rounded in cross section with one groove
- longitudinal groove of body length
- length 10–30 µm
- posterior end rounded
- anterior end obliquely truncated
- leading flagellum about twice of body length
- trailing flagellum short, about quarter of body length
- nucleus central
- reservoir with adjacent contractile vacuole
So far I have only found a few specimens of Sphenomonas angusta in an old sample from May 2024 taken from the upper mud layer in the Simmelried. After about two weeks, a brown-green fringe rich in small flagellates and euglenids formed on the vessel wall just below the water surface.
I was able to recognize Sphenomonas angusta mainly by the body shape (round in cross section) with a longitudinal groove running over the entire body. The cells have a short trailing flagellum and a long leading flagellum. There were only two deviations from the description by Schroeckh et al. (2003) in my population. The trailing flagellum was only 4.0–4.5 µm long, which corresponds to about one sixth of the body length and not a fourth as stated by Schroeckh et al. Instead of a large gelatinous body my specimens had several small bodies, which appeared homogeneous and also gelatinous. Otherwise, all characteristics correspond to the description by Schroeckh et al.
Fig. 1 a-g: Sphenomonas angusta. L = 23 µm. Different focal planes of a freely swimming specimen. Note the longitudinal groove (LG) over the whole length of the body and the obliquely truncated anterior end (arrow). CV = contractile vacuole, LF = leading flagellum, NU ? = probably the nucleus, TF = trailing flagellum. Obj. 100 X.