Ovate Marsh Runner
Agonum fuliginosum
The Ovate Marsh Runner (also known as the Sooty Marsh Beetle) is a small ground beetle, 6 to 8 mm in length, belonging to the Carabidae family. It is characterized by its distinct broad-ovate shape and shiny black coloration. The species is a hygrophilous specialist, preferring extremely wet habitats such as bogs, swamp forests, and muddy riparian zones.
Details
Identification
Body broadly ovate; pronotum significantly wider than long; upper side deep black and shiny; legs usually dark, often with lighter tibiae.
Social behavior
Solitary, but can occur in high densities in leaf litter under favorable conditions.
Diet
Predatory lifestyle; feeds on small invertebrates such as mites, springtails, and small insect larvae.
Hunting strategy
Active searching in leaf litter and vegetation during the night.
Spawning substrate
Moist substrate, detritus.
Overwintering
Overwinters as an adult in moss cushions or under bark.
Ecology
Ecological role
Important predator in semi-aquatic food webs, regulating populations of micro-invertebrates.
Natural predators
Spiders, amphibians (e.g., common toads), insectivorous birds.
Competitor species
Other hygrophilous ground beetle species of the genera Agonum and Pterostichus.
Ecosystem service
Pest control in moist forest and agricultural ecosystems.
Threats
Drainage of bogs and wet meadows, loss of alder carr forests, climate change (drying of habitats).
Scientific profile
Profile
Distinguishing features
Characteristic is the heart- to egg-shaped pronotum, the sides of which are strongly rounded and the hind angles of which appear completely rounded. The elytra have fine punctured striae and usually feature three dorsal punctures in the third interval. Compared to related species of the genus Agonum, the body build is more compact and the pronotum shape is specifically oval.
Habitat
Stenotopic hygrophilous species. It inhabits very moist to wet, shaded locations. Typical habitats include alder carrs, fens, sedge marshes, muddy riparian zones of stagnant waters, and damp deciduous forests with a distinct humus or moss layer.
Diet
Zoophagous; both adults and larvae are predatory, feeding on small invertebrates such as mites, springtails (Collembola), small insect larvae, and worms.
Role in food web
Secondary consumer; regulates populations of small soil arthropods and serves as prey for larger predators such as amphibians, shrews, and larger predatory insects.
Protection & threats
Main threats
Drainage of wetlands, lowering of the groundwater table, intensification of forestry (esp. conversion of carr forests), loss of riparian buffer zones, and general habitat desiccation due to climate change.
Population trend
Often common and stable in suitable habitats; however, regional declines have been recorded due to habitat loss and drainage.
Conservation measures
Maintenance and restoration of natural water levels in fens and floodplains, protection of alder carr forests from forestry use, restoration of drained wetlands.