Microgromia minor (de Saedeleer, 1934)
Most likely ID: n.a.
Synonym: n. a.
Sampling location: Simmelried
Phylogenetic tree: Microgromia minor
Diagnosis:
- shell retort-shaped, outline circular sometimes elongated with a dorsal tip
- length of shell 14 – 25 µm
- shell hyaline and thin
- short neck, obliquely oriented to shell outline
- one side of the neck is a slightly concave transition of the shell outline
- neck with a septum
- nucleus central with a spherical nucleolus
- contractile vacuole near neck
- granuloreticulopodia very thin, anastomosing, arising from a peduncle
I found Microgromia minor between 2005 and 2014 in the Simmelried. Mostly the specimens were found there on gelatinous colonies of cyanobacteria (probably Aphanothece spec.), on which it fed. I did not find any more specimens after 2014.
Microgromia minor looks similar to Microgromia haeckeliana, but one side of the neck is an extension of the shell outline, with a slightly concave indentation (s fig. 1). In my population there were also some specimens with an elongate deformed shell, which terminated in a short tip at the dorsal margin (s. figs. 2 and 5 a-b). Otherwise the outlines of the shells were mostly circular.
Fig. 1: Microgromia minor. L = 17 µm. Lateral view of specimen. Note the slightly concave transition of the shell outline into the neck (arrow). Obj. 100 X.
Fig. 2: Microgromia minor. L = 17 µm. A second specimen feeding on cyanobacteria (likely Aphanothece spec.). Note the dorsal tip of the shell. Obj. 100 X.
Fig. 3: Microgromia minor. L = 14 µm. A third specimen feeding on cyanobacteria. Obj. 100 X.
Fig. 4: Microgromia minor. L = 13 µm. A fourth specimen feeding on cyanobacteria. Obj. 100 X.
Fig. 5: Microgromia minor. L = 15 µm. Two focal planes of a specimen feeding on cyanobacteria. Obj. 100 X.
Fig. 6: Microgromia minor. L = 16 µm. Two specimens in a feeding community. Obj. 100 X.