Thermocyclops oithonoides
Termocyclops oithonoides has a long and slender body form and is the smallest species among the planktonic copepods in Norway. Its occurrence is restricted to the lowland of south-east Norway where it often co-occur with Mesocyclops leuckarti.
Key characteristics
Thermocyclops oithonoides (female)
Thermocyclops oithonoides is the smallest species among the planktonic copepods. It has a long and slender body form. Based on its habitués it is therefore relatively easy to distinguish this species from Mesocyclops leuckarti and the two other species which belongs to the Thermocyclops genus. In addition, the short length of the outer seta attached to the furca can be used as a criterion to define T. oithonoides. Its body is highly pellucid, with a faint yellow tinge.
Female: Length 0.8–1.0 mm
Male: Length 0.7 mm
Ecology and distribution
T. oithonoides is mainly a plankton species which is found in more than 8 % of the localities, and its occurrence is restricted to the lowland of south-east Norway. All records, except for a few, are from water bodies situated below 300 m a.s.l. Though it is found in water bodies of all sizes the chance to find T. oithonoides increases when surface area increases. It has a relatively wide tolerance to pH (4.7–7.9) and electrolyte rich water seems to favour the species which co-occur with M. leuckarti in 83 % of the actual water bodies.
| Vitenskapelig navn | < 4,5 | 4,5 - 4,9 | 5,0 - 5,4 | 5,5 - 5,9 | 6,0 - 6,4 | 6,5 - 7,0 | 7,0 - 7,4 | > 7,5 |
|---|---|---|---|---|---|---|---|---|
| 0 | 0,9 | 5,1 | 9,8 | 13,2 | 11,2 | 5,6 | 5,6 |
| Vitenskapelig navn | < 1,0 | 1,0 - 1,4 | 1,5 - 1,9 | 2,0 - 2,9 | 3,0 - 3,9 | 4,0 - 4,9 | 5,0 - 6,9 | 7,0 - 9,9 | > 10,0 |
|---|---|---|---|---|---|---|---|---|---|
| 0 | 1,7 | 3,8 | 3,8 | 6,1 | 13,6 | 20,6 | 12,7 | 12,1 |
| Vitenskapelig navn | < 0,01 | 0,01 - 0,09 | 0,1 - 0,9 | 1,0 - 9,9 | 10,0 - 99 | 100 - 999 | > 1000 |
|---|---|---|---|---|---|---|---|
| 0 | 4,1 | 5,5 | 7,1 | 8,6 | 9,3 | 13,6 |
| Vitenskapelig navn | < 100 | 100-299 | 300-499 | 500-699 | 700-999 | >1000 |
|---|---|---|---|---|---|---|
| 7,4 | 22 | 3,4 | 0 | 0 | 0 |
Look alikes
Thermocyclops crassus, T. dybowskii and Mesocyclops leuckarti
