Pterostichus stygicus

Say, 1823

Woodland ground beetle

Pterostichus stygicus is a of ground beetle in the Carabidae, native to North America. It inhabits deciduous forest floor environments where it functions as a . The species has been studied for its competitive interactions and intraguild relationships with centipedes, particularly Scolopocryptops sexspinosus.

Pterostichus stygicus by (c) Bill Keim, some rights reserved (CC BY). Used under a CC-BY license.

Pterostichus stygicus by (c) Owen Strickland, some rights reserved (CC BY), uploaded by Owen Strickland. Used under a CC-BY license.

Pronunciation

How to pronounce Pterostichus stygicus: /tɛɹoʊˈstɪkəs ˈstɪdʒɪkəs/

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Images

Habitat

Deciduous forest floor; specifically beneath rocks and logs on the forest floor, especially during dry periods when prey become confined to such microhabitats.

Distribution

North America; recorded from Canada and the United States.

Diet

; consumes leaf litter mesofauna. Prey items overlap with those of co-occurring centipedes (Scolopocryptops sexspinosus).

Behavior

Engages in competition and intraguild with centipedes (Scolopocryptops sexspinosus). In laboratory mesocosms, exhibits negative co-occurrence with centipedes beneath cover objects. Loses mass under solitary, intra- and interspecific conditions. Shows less favorable response to competition compared to centipedes.

Ecological Role

in forest floor . Participates in intraguild dynamics that may weaken top-down control on lower .

More Details

Intraguild predation dynamics

Laboratory studies demonstrate asymmetric intraguild between P. stygicus and Scolopocryptops sexspinosus, with high mortality of beetles when paired with centipedes. Centipedes maintained weight across treatments while beetles lost mass in all conditions, suggesting differential competitive ability.