Length 4.5 to 6 mm. This is a long, slim, reddish brown ground beetle. The head is barely longer than wide (ignoring the mandibles).

P. longiceps has a head that is notably longer than wide and it usually has a dark midline around the elytral sutures.

Damp grassland and marshy places where it can be found in sedge and reed litter.

Spring and summer.

Widespread and frequent in England and Wales, more coastal in Scotland.

Fairly common in Leicestershire and Rutland. There were a total of 124 VC55 records for this species up to March 2015.