A medium-sized bug (4 to 5mm) with a dark pubescent and coarsely punctate pronotum.  The fromt femora have one large tooth and several smaller ones.  The legs and 2nd antennal segment are entirely pale brown.  It is usually brachypterous, with short wings not reaching the end of the abdomen. 

Other Megalonotus species

Good photographs of a specimen or taken in the field, to show the legs and antennae. 

A variety of open habitats

All year. 

Ns/Nb (Nationally Scarce/Notable B) - ref: British Heteroptera checklist 2021, on British Bugs website)

Rarely recorded

https://www.britishbugs.org.uk/heteroptera/Lygaeidae/megalonotus_antennatus.html