Length 5-8mm. A completely black shieldbug, sometimes with a bronzy sheen, wing membrane variable, light or dark. Margins of head and pronotum without bristles. 

There is a closely-related species present in the UK, Sehirus morio, which seems to be turning up in greater numbers: 
Sehirus luctuosus, typical length 5-8mm; Sehirus morio, typical length 8-12mm - note size overlap. If in doubt, please retain a specimen for examination, male parameres are distinctive. 

This species is associated with forget-me-not (Myosotis sp.) particularly on light chalky soils with a warm open aspect.

All year round.

There is one generation per year and the new generation is complete by August. Feeds on forget-me-not seeds.

Widespread but local in southern Britain, but probably overlooked due to its rather unobtrusive habits.

Occasional in Leicestershire and Rutland.