It is endemic to New Zealand, where it is known very locally, and very infrequently, from the southern half of the North Island: two specimens collected in 2016 were the first seen for 30 years.

This species was described by Edward Meyrick in 1892 using a female specimen collected by George Hudson in Wellington and named Semiocosma caustopa.

Forewings elongate, costa moderately arched, apex rounded, hindmargin almost straight, oblique; fuscous-whitish, suffusedly mixed with fuscous and dark fuscous, veins remaining pale posteriorly; a dark-fuscous basal patch, its outer edge angulated on discal tuft; a large dark fuscous trapezoidal blotch occupying whole of disc, posterior edge well defined, near and parallel to hindmargin, other edges suffused; a cloudy blackish dot in disc at 1⁄3; a cloudy black longitudinal streak from middle of disc to near apex, upper edge forming a rounded projection before 2⁄3 of disc, posterior extremity irregular, surrounded by fuscous suffusion : cilia fuscous, mixed with fuscous- whitish.

[4] Hudson noted this species was found in a few patches of tree fuchsia at Gollans Valley and Wilton's Bush, Wellington; he collected his last specimen in 1942.

[8][9] Hudson reared the moths from dead branches of kōtukutuku (Fuchsia excorticata) collected in Karori, Wellington.

[4] It may actually be quite common in small pockets of forest in the North Island, and simply have been overlooked, since it is not attracted to bright light the way most moths are;[9] the specimens at Bushy Park were caught in a Malaise trap.