Trechus obtusus

Erichson, 1837

Trechus obtusus is a ground beetle in the Carabidae, originally described from Europe and now established as an in Hawaii. It has been documented in large numbers in pitfall traps at Pu'u Maka'ala Natural Area Reserve on the island of Hawaii, where it may compete with or displace native carabid species. The species has a broad native distribution spanning North America, Europe, and Africa, with six recognized showing regional variation.

Trechus obtusus - inat 246631819 by {{{name}}}. Used under a CC BY 4.0 license.

Trechus obtusus Erichson, 1837 by URSchmidt. Used under a CC BY-SA 4.0 license.

Planche XII Coléoptères du Sannoisien de Kleinkembs Nicolas Théobald 1937 thèse by Philippe rogez. Used under a CC BY-SA 4.0 license.

Pronunciation

How to pronounce Trechus obtusus: /ˈtrɛkʊs ɒbˈtjuːsəs/

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Habitat

In its native range, Trechus obtusus has been recorded from diverse terrestrial . In Hawaii, it has been captured in pitfall traps in forest floor habitats at Pu'u Maka'ala Natural Area Reserve, suggesting occupation of terrestrial microhabitats within forest .

Distribution

Native to North America, Europe, and Africa. Introduced and established in Hawaii, specifically documented on the island of Hawaii (Maui also mentioned in literature). Distribution records include Canada, USA, (former) Yugoslavia, Albania, and Algeria. The has shown distributional expansion in Hawaii since its introduction.

Ecological Role

In Hawaii, Trechus obtusus has been identified as an of concern for native carabid . Its presence in large numbers in pitfall traps suggests potential competitive impacts on native , particularly members of the Mecyclothorax. The species' invasion status makes it a subject of monitoring for impacts.

Human Relevance

Trechus obtusus is of conservation concern in Hawaii as an that may threaten native ground beetle diversity. It has been specifically noted by researchers monitoring carabid at National Ecological Observatory Network sites as an example of non-native establishment affecting native fauna.

Similar Taxa

Mecyclothorax spp.Native Hawaiian ground beetles in the same (Carabidae) that may be affected by competition from Trechus obtusus; distinguished by status and typically more specialized microhabitat associations on volcanic terrain
Other Trechus speciesCongeneric ground beetles with similar general ; identification to level requires examination of specific characters not detailed in available sources

More Details

Invasion History in Hawaii

The has been documented in Hawaii with sufficient abundance to trigger research attention regarding its distributional expansion and potential impacts on native carabid . This represents a notable biogeographic shift from its native Holarctic and African range.

Subspecies Diversity

Six are recognized: T. o. asturicus (Spain), T. o. battonii (Italy), T. o. lucanus (Italy), T. o. obtusus (nominate, Europe), T. o. sejunctus (Congo), and T. o. thracicus (Bulgaria/Turkey), indicating substantial geographic variation across its native range.