Description: 4.5-5.5mm long black ground beetle with bluish or greenish reflections, found on gravel or shingle banks by rivers. Very similar to B. atrocoeruleum but more local and northern.

NI account: Added to the Irish list from a streambank at Glenariff, Antrim (Speight et al., 1983). Three further sites have been found in the Sperrin Mountains, Londonderry. Widely but locally distributed in northern Britain, principally in the north Pennines (Luff, 1998).

Ecology: Sowig (1986) suggests that because of very similar substrate and humidity preferences, geniculatum and atrocoeruleum avoid competition by living at different altitudes in the Black Forest. In Ireland, geniculatum has been found with B. atrocoeruleum in one locality, and with B. tibiale at the other three, although, on average, it is recorded from slightly higher altitudes (100-300m) than atrocoeruleum. B. geniculatum also appears to have the more northern range of the two in Ireland, and searches of seemingly suitable montane streambanks in the southern and western counties of Kerry, Galway and Mayo have so far been unsuccessful.

Distribution: A European Boreal-montane species (43) with a restricted European range and recorded from the Alps, the Pyrenees and the Balkans. Also found on hill land in the north and west of the British Isles.

Similar Species: Bembidion atrocoeruleum: base of pronotum oblique laterally; apex of elytra truncate (Fig. 54) B. tibiale: larger, flatter

Key Identification Features:

• Small, convex (4.5-5.5mm)
• Terminal segment of palpi much reduced (Fig. 31)
• Second elytral stria as strong as first; all striae fairly strong to apex
• Riparian on streambanks
• Convex, slender
• Base of pronotum straight - see tibiale (Fig. 53)
• Apex of elytra acuminate (pointed) (Fig. 54)

Distribution Map from NBN: Bembidion geniculatum at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Bembidion geniculatum at iNaturalist World Species Observations database.

GBIF data for Bembidion geniculatum | Classification: Insecta, Coleoptera, Carabidae, Bembidion

Thumbnails for genus Bembidion