The postabdomen of Alona costata is relatively long and slender, and posterior it forms a distinctly angled corner. It is missing in the southern and western parts of south Norway and characterized as moderate sensitive towards acid water.
The postabdomen (female) of Alona costata is relatively long and slender, and posterior it forms a distinctly angled corner. From this, each side of the posterior edge, roughly to the middle, is covered with twelve to fourteen rather coarse and short teeth. The carapace has a pale yellowish green colour and with especially sharply marked longitudinal stripes.
Female: Length 0.4–0.7 mm
Male: Length 0.3–0.5 mm.
Ecology and distribution
A. costata occurs in 4 % of the investigated lakes, missing in the southern and western parts of south Norway. In northern Norway it is only recorded from the eastern parts. It is found between 3 and 673 m a.s.l., in both small pools and large lakes. It seems to prefer algal-rich habitats on or near the substrate. A. costata is found in localities having pH between 5.5 and 8.3. The species is most common in electrolyte-rich waters and is not found in waters with conductivity below 1.7 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|