Collotheca pelagia Rousselet, 1893
Most likely ID: n.a.
Synonym: n.a.
Sampling location: Lake Constance, Pond the waste disposal company Constance
Phylogenetic tree: Collotheca pelagica
Diagnosis:
- body slender, cylindrical
- corona circular, with short cilia
- corona only slightly wider than body
- foot slender and long, sometimes thickened distal end
- length 300–500 µm
- in a gelatinuous case
- eyespot absent
- up to 5 amictic eggs deposited in gelatinuous case
- free-swimming, planktonic lifestyle
I rarely find Collotheca pelagica. So far I have only been able to find this rotifer in the plankton of Lake Constance and in the pond of the waste disposal company Constance.
Collotheca pelagica is a pelagic rotifer that lives in a self-made gelatinous casel. The case extends to about the anterior third of the body. The posterior end of the case is conical and shaped into a blunt tip. The unfertilized, amictic eggs are also deposited in the case. The corona is circular and not lobed, as in other species of the genus Collotheca. This makes it easy to distinguish Collotheca pelagica from the similar species Collotheca mutabilis, which also lives pelagically but has a clearly two-lobed corona. In addition, the corona of Collotheca pelagica is only formed by short cilia that appear almost bristle-like.
Further images and information on Collotheca pelagica: Michael Plewka-Freshwater life-Collotheca pelagica
Fig. 1 a-b: Collotheca pelagica. L = 220 µm. A young specimen with a partly contracted (a) and extended conrona (b). Obj. 40 X.
Fig. 2: Collotheca pelagica. L = 345 µm. An adult specimen with 3 amictic eggs (AE) deposited in the gelatinuous case (GC). CO = corona, ST = stomach, Vit = vitellarium. Obj. 40 X.