Length 10.5 to 12.5 mm. With a closer look at Rhantus suturalis the dense black punctuation of the elytra is visible; this punctuation on a golden yellow base gives the dark brown impression when seen from a normal distance. The beetle has a light yellow coloured margin, and a rhombus-shaped dot on the neck shield.

Stillwater habitats, including newly created pools and pools that dry out in summer.

All year round.

It inhabits pools that dry out in summer, which are also the breeding places of mosquito larvae, which are the preferred food of this beetle. They can fly very well, and so easily escape from a pool which is drying out and migrate to another.

Quite common and widespread in Britain.

Fairly frequent in Leicestershire and Rutland. There were a total of 23 VC55 records for this species up to March 2015.