Anchistropus emarginatus lives as an ectoparasite on Hydra sp, attached to its host with the help of its strong claws on the first pair of legs. The majority of records are from the south-eastern parts of Norway.
This species resembles the species of the genus Chydorus in having an oval form. However, the dorsal part of the carapace has a characteristic form being especially strongly curved. Ventrally a conspicuous inclination notch is seen in the carapace. The rostrum is long, thin and is pointed backwards. The first pair of legs wear strong claws. Its colour varies from strong yellow to brown.
Female: Length 0.4–0.5 mm
Male: Length 0.3–0.4 mm
Ecology and distribution
A. emarginatus is a littoral species only recorded from 1,4 % of the investigated localities in Norway, mainly situated in the south-eastern parts of Norway. It is found between 25 and 817 m a.s.l. with the majority of records from below 300 m a.s.l. A. emarginatus is not found in lakes <1 da, as small tarns and ditches. It lives as an ectoparasite on Hydra sp, attached to its host with the help of its strong claws on the 1st pair of legs. It is only found in samples from water vegetation, and except for one record at pH 4.8, all are from lakes with pH between 6.0 and 7.4 and conductivity between 1.6 and 25.3 mS/m.
|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|
|Vitenskapelig navn||< 0,01||0,01 - 0,09||0,1 - 0,9||1,0 - 9,9||10,0 - 99||100 - 999||> 1000|
|Vitenskapelig navn||< 100||100-299||300-499||500-699||700-999||>1000|
|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|