Ground Beetles of Ireland

Pterostichus rhaeticus

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Pterostichus rhaeticus
© Roy Anderson
Pterostichus rhaeticus
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(Maps updated 30th November 2009)

Pterostichus rhaeticus Heer

Description: An 8-11mm long black ground beetle, externally indistinguishable from P. nigrita although in general smaller in size. Sometimes found with that species but in general prefers upland, exposed habitats.

World Distribution: A recent segregate of P. nigrita (Koch, 1986), found widely in Europe including the British Isles and Fennoscandia. Its wider distribution is poorly known, but almost certainly northern, and we provisionally classify it here as Eurosiberian Boreo-montane (44).

Irish Status: Widespread and common in hill areas, at least in northern counties. Status elsewhere uncertain. Only verified records are included in the map.

Ecology: Best distinguished from P. nigrita on the structure of the male and female genitalia (Koch, 1986). It is generally smaller and more slender than that species and always uniformly dark. The two can occur together, as in the Erne River System of Fermanagh, but this is the exception rather than the rule. Our records indicate that P. rhaeticus is a cold-adapted species inhabiting exposed, nutrient-poor and upland environments while P. nigrita is primarily a lowland riparian species.