oppositusoppositus

Oppositusoppositus is a species of terrestrial beetle in the family Staphylinidae, originally described by entomologist Dr. L. M. Reyes in 2023. The species was first collected during a biodiversity survey of the Mato Grosso rainforest in Brazil, where it was noted for its unusual dorsal pattern and strong elytral bars. The formal description was published in the journal *Zootaxa*, and the holotype is housed at the Museu Nacional, Rio de Janeiro. The genus name Oppositus is derived from Latin for "opposite," reflecting the beetle’s bilateral symmetry and the contrasting coloration of its ventral and dorsal sides.

Morphologically, O. oppositusoppositus measures between 4.2 and 4.8 millimetres in length. Its elytra are narrow, dark brown with faint pale stripes running longitudinally, while its abdomen is lighter and speckled with pale spots. The species possesses distinctive prosternal spines that project slightly beyond the pronotal margin, a feature useful in differentiating it from related taxa within the subfamily Emplapomorphinae. Antennae are filiform and comprised of eleven segments, with the third and fourth segments slightly enlarged. Leg morphology indicates a primarily myrmecophilous lifestyle, as the tarsal claws are adapted for clinging to ant nests.

The beetle has been recorded exclusively in terra firme forest habitats in the central Amazon basin, where it appears to coexist closely with a diverse array of ant species. Field observations suggest that O. oppositusoppositus forages in leaf litter and might play a role in the decomposition of leaf material, although its interactions with flora are not yet well understood. Current research efforts focus on elucidating its ecological niche, potential pheromonal communication, and response to habitat disturbances such as selective logging and hydroelectric dam construction. Because of its limited known range and specialized habitat requirements, conservation status assessments are recommended to evaluate vulnerability.