Up to 5mm with a densely dusted grey thorax and abdomen, except for the final abdominal segment (terminalia) that is glossy black.  The legs, the front of the frons and the antennae are orange. The arista are pubescent. 

N. spinimanum is larger (~6.5mm) and is less dusted so that the shiny black tergites show through.

Detailed photos required.

Wetlands, damp meadows and along margins of rivers, canals, reservoirs, etc. 

The larvae develop in the petioles of Meadowsweet. 

Widespread but scarce. 

Uncommon.