Gastrobothrus trigonus is a species of beetle of the family Staphylinidae. It is found in New Zealand (North Island).
Description Adults reach a length of about . The body is reddish-brown, with the elytra and appendages yellowish-brown.
Life history They have been collected in leaf litter.
Etymology The species name is derived from Latin trigonus (meaning three-angled) and refers to the triangular abdominal spatula of this species.
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