Size: 4.5-6.0mm
Basic colour: Metallic blue, purple, green, brassy, bronze or almost black.
Pattern colour: None
Number of spots: None
Other colour forms: Common
Pronotoum: As basic colour
Leg colour: As basic colour

Size: 5-6mm
Basic colour: Metallic green, blue or brassy, with yellow or reddish stripes.
Pattern colour: Pronotum with yellow or reddish margins; elytra also with yellow or reddish margins plus a longitudinal band of the same colour along interstices 3 & 4.
Number of spots: None
Other colour forms: Sometimes
Pronotoum: See 'pattern colour' above.
Leg colour: Black and yellow or reddish

Size: 4-5mm
Basic colour: Dark metallic blue (rarely green)
Pattern colour: None
Number of spots: None
Other colour forms: Rare
Pronotoum: As basic colour
Leg colour: As basic colour

Size: 3.4-4.5mm
Basic colour: Dark metallic blue and orange-yellow
Pattern colour: Pronotum with yellowish lateral margins.
Number of spots: None
Pronotoum: See 'pattern colour' above.
Leg colour: Dark metallic blue
Confusion species: Hydrothassa glabra
, Confusion species: Hydrothassa hannoveriana

Size: 3.5-5.0mm
Basic colour: Dark metallic blue and orange-yellow or reddish
Pattern colour: Dark metallic blue; pronotum with orange-yellow side margins, elytra with yellowish or reddish median longitudinal stripe and yellowish side margin. These elytral marks may fuse, especially at the rear in females; the median stripe may be broken/absent.
Number of spots: None
Other colour forms: None
Pronotoum: See 'pattern colour' above.
Leg colour: Dark metallic blue
Confusion species: Hydrothassa glabra
, Confusion species: Hydrothassa marginella