Helastia semisignata

It was first described by Francis Walker in 1862 using specimens collected by A. Sinclair in Auckland and originally named Larentia semisignata.^[4][3][2] In 1877 Arthur Gardiner Butler synonymised Cidaria dissociate and Cidaria semisilata with L. semisignata.^[5] In the same publication Butler also mistakenly synonymised Larentia corcularia with L. semisignata.^[5] This taxonomic error was correct by R. C. Craw in 1987.^[2] In 1912 L. B. Prout placed this species in the genus Xanthorhoe.^[6] This placement was followed by George Hudson in his 1928 book The butterflies and moths of New Zealand.^[7] Subsequently, in 1971, J. S. Dugdale placed this species in the genus Helastia.^[8] R. C. Craw confirmed this placement in his revision of the genus in 1987.^[2] The male holotype is held at the Natural History Museum, London.^[3]

Walker described this species as follows:

Cinereous, minutely black-speckled. Head wanting. Fore wings with several denticulated blackish lines, some of which are most conspicuous on the veins, where they form black points; middle space without lines, containing the black transverse elongated discal point; interior, exterior and submarginal lines formed by whitish points on the veins; marginal lunules black; costa convex; exterior border hardly convex. Hind wings paler, with indistinct lines. Length of the body 4 lines; of the wings 12 lines.^[4]

Species in the genus Helastia can be difficult to distinguish from one another.^[9] However this species normally has orange scaling present on its forewings and its wing veins have black and white patches.^[9]

This species is endemic to New Zealand.^[1] It is found in the North Island only.^[9]

H. semisignata can be found in a variety of habitats at a variety of altitudes including native forest and scrubland, subalpine herbfields and in coastal areas.^[9] This species also inhabits developed areas such as parks and gardens.^[9]