In Denmark male unique. Separated from whitefaces by black frons.
Immatures and females have a brown triangle on top of thorax, where Ruddy shows a T-shape. And they show three yellow dots on side of black part of the thorax. The vulvar scale on females is as prominent as on Moustached Darter.
Wing marks are white on immatures and black on mature individuals. Have seen a photo on artportalen.se where a male showed white appendages. Perhaps also an immature feature?
Most of Europe; absent Mediterranean region and northern Fennoscandinavia. Also present east through Russia to China, Korea and Japan. Also present N America, especially W Lower 48 and southern C and E Canada. In Denmark present in all regions, but mainly NE Sjælland, most of Jylland and Bornholm.
LC in Denmark. VU in Europe. LC globally. In Denmark considered relatively widespread and stable, but generally it is decreasing in Europe due to suited habitat loss.