Chydorus gibbus Lilljeborg

Chydorus gibbus is distinguished from other Chydorus species by the shape of the carapace which is less oval and looks more or less triangular. As in C. sphaericus the postabdomen is short. However, the teeth are somewhat coarser in C. gibbus than in C. sphaericus. Its colour is mainly brown, sometimes with a tinge of green or red.

Female: Length 0.5–0.6 mm

Male: Length 0.4–0.5 mm

C. gibbus is only recorded from a limited number of localities with a scattered distribution in Norway. It is so far not found in Trøndelag and county Nordland, and otherwise it has a scattered distribution. Except for two records from about 1100 m a.s.l, the remaining records are from below 300 m a.s.l. C. gibbus is most common on sandy bottom in the littoral of lakes and is not found in ditches and small ponds (<0,1 ha). pH varies between 5.3 and 7.8. It is found in brakish water (957 mS/m) and seems therefore to be very tolerant towards electrolyte rich water.