Key for imagines:
(Note 1: use only to identify German species; key may not be valid for other countries)
(Note 2: key accounts for normal individual variation, but should not be used to identify strong aberrations or damaged specimens)

1 (a)   Head and mesonotum on upper side with reticulate and corrugated wrinkled structure..........Helorus nigripes
1 (b)   Head and mesonotum on upper side smooth or slighly punctated..........2

2 (a)    Petiolus short and compact, length/height ratio in lateral aspect is 2.0 to 2.1. Pterostigma long and narrow, length/height ratio is 3.3 to 3.5 (see Fig. 1)..........Helorus anomalipes
2 (b)   Petiolus long and slender, length/height ratio in lateral aspect is at least 2.5 (usually above 3.0). Pterostigma compact, length/height ratio is 2.0 to 3.0 (see Fig. 1)..........3

3 (a)   Femur of leg pair 1 partially dark and femur of leg pair 2 and 3 almost entirely dark (see Fig. 2)..........Helorus meridionalis
3 (b)   Femur of leg pair 1 and 2 light (usually yellow) and only femur of leg pair 3 almost completely dark (see Fig. 2)..........4

4 (a)   Pterostigma spherical compact, length/height ratio is 2.0 to 2.3. Body coloration usually dark (black or brown)..........Helorus coruscus
4 (b)   Pterostigma less spherical, length/height ratio is 2.3 to 2.6. Body coloration usually reddish brown..........Helorus ruficornis