Collotheca mutabilis Hudson, 1885
Most likely ID: n.a.
Synonym: n.a.
Sampling location: Lake Constance
Phylogenetic tree: Collotheca mutabilis
Diagnosis:
- body slender, cylindrical
- corona with 2 lobes, wider than body
- the outer cilia of corona longer than inside
- foot slender and long, sometimes thickened distal end
- length 140–580 µm
- in a gelatinuous case
- 2 eyespots in dorsal lobe
- free-swimming, planktonic lifestyle
I have found Collotheca mutabilis only once in September 1998 in the plankton of Lake Constance. After that I have not recorded any further finds.
Collotheca mutabilis is a pelagic rotifer that lives in a self-made gelatinous case. The animals can withdraw completely into the case. The unfertilized, amictic eggs are also deposited in the shell. The corona is typical and consists of two lobes. There are two eyespots in the dorsal, larger lobe. This makes it easy to distinguish Collotheca mutabilis from the similar species Collotheca pelagica, which also lives pelagically, but has a circular corona with short cilia and without eyespots. In Collotheca mutabilis, the outward-facing cilia are considerably longer than the cilia on the inside of the lobes.
More images and information on Collotheca mutabilis: Michael Plewka-Freshwater life-Collotheca mutabilis
Fig. 1: Collotheca mutabilis. L = 270 µm. A freely swimming specimen found September 1998 in Lake Constance. Note the two lobes of the corona. Obj. 20 X.
Fig. 2: Collotheca mutabilis. L = 270 µm. The same specimen as shown in fig. 1 in detail. Note the gelatinuous case (GC). Obj. 40 X.