Sminthurinus species are very variable in colour pattern and it is essential to examine the presence or absence of ventral subapical setae on the dens in order to make a correct identification.
Sminthurinus lawrencei reaches 1.0 mm in length and is completely black violet in colour. Ventral subapical setae are ABSENT from the dens which would suggest that it belongs to the 'aureus-group'. In Sminthurinus lawrencei, however, the mucro is serrated on both the inner and outer edges (only the inner margin is serrated in Sminthurus aureus) and there are minor differences in the arrangement of setae on the dens.
Sminthurinus lawrencei was described as a new species by Gisin (1963) based on specimens collected from Keston Common, Kent in November 1962 by Peter Lawrence (red dot on the map). Steve Hopkin examined the Holotype and several paratypes in the NHML slide collection. Unfortunately, the method of mounting by Gisin makes it very difficult to see the exact arrangement of setae on the dens and there must remain some doubt as to the validity of Sminthurinus lawrencei as a good species. The only other record is from Thursley Common in 1994 (green dot) reported by Shaw (1997); these specimens have preserved poorly but the mucro is clearly visible and they still key to this species.