Ogdoconta tacna is a moth in the family Noctuidae first described by William Barnes in 1904.

The orbicular and reniform spots are clearly outlined by fine, dirty-white lines.

The postmedial line is mostly straight and oblique from the costa to the posterior margin, although there is a slight outward pointing angulation near the bottom of the reniform spot.

The postmedial line is accented with vague dark gray-green rectangles on its inner side.

The female hindwing is more generally suffused with dark scales.