It was first described by Edward Meyrick in 1880 using two male specimens taken in forest at the Wellington Botanic Garden in January and named Erechthias chasmatias.

[6] George Hudson discussed and illustrated this species in his 1928 book The butterflies and moths of New Zealand under that name.

Fore-wings white, with dark fuscous markings; a broad streak along inner margin from base to beyond middle, where it is attenuated and bent upwards, ending on disc beyond middle; a slender straight line from base of costa through disc to apex, interrupted at 3⁄4, beyond which it becomes much broader, containing a black longitudinal streak and ending in a round black apical spot; a short very oblique blotch on costa beyond middle; a black streak along costa from about 3⁄4 to apex; an elongate streak on Kind-margin about anal angle, attenuated at both ends; cilia white, with two blackish dividing lines throughout, and indications of a projecting hook at apex.

Hind-wings whitish-grey, cilia whitish, with two dark fuscous cloudy lines round apex.

[9] The adults of this species are on the wing from October to April but are most commonly observed in November to January.