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 have not been able to 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 elongately 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 a-b: 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.