This species is endemic to New Zealand and has been observed in the Mackenzie and Otago Lakes districts of the South Island.

Upperside forewing coloured whitish purplish brown with darker transverse basal, antemedial and postmedial lines; oblique purplish brown apical streak.

[3] The entomologist Graham White has stated that the size of the discal dot in H. angusta is smaller than that of H.

[6] Moth species closely related to H. angusta have larvae that feed Helichrysum lanceolatum.

[3][8] This moth is classified under the New Zealand Threat Classification system as being "At Risk, Relict".