Ichneutica omicron

Karori, type locality of this species

This species was described and illustrated by George Hudson in 1898 and named Melanchra omicron.[3] It was discovered by Albert Norris in Karori, Wellington.[3] The type specimen is missing and has not been found at Museum of New Zealand Te Papa Tongarewa.[4][5] The neotype can be found in the New Zealand Arthropod Collection.[2] In 1928 Hudson, thinking M. omicron was the same species as Aletia inconstans, discussed it under the latter name in his book The Butterflies and Moths of New Zealand.[4] In 1939 Hudson reinstated M. omicron as a separate species.[6] In 1988 John S. Dugdale placed this species within the genus Graphania.[4] In 2019 Robert Hoare undertook a major review of New Zealand Noctuidae.[2] During this review the genus Ichneutica was greatly expanded and the genus Graphania was subsumed into that genus as a synonym.[2] As a result of this review, this species is now known as Ichneutica omicron.[2]

Hudson described the species as follows:

The expansion of the wings is about 1+1⁄2 inches. The fore-wings are pale olive-green, mottled and striped with dull grey; there is a double transverse line near the base, another at about one-fourth, and another at about one-half, passing between the orbicular and the reniform; beyond this, there are two indistinct shaded lines, and a terminal series of black marks; the orbicular is large, almost circular, and sharply outlined in black; the claviform is small and indistinct, and the reniform ill-defined, obscurely outlined in black towards the base. The hind-wings are brownish-grey, darker towards the termen.[3]

This species is almost indistinguishable visually from its sister species I. barbara.[2] The only visual difference is in the males with I. barbara having a yellowish anal tuft where as the male of the I. omicron has a grey anal tuft.[2] However I. barbara is only known from the South Island and so confusion between the species is unlikely.[2]

This species is endemic to New Zealand.[7][8] This species is known from the North Island only and has been observed in the central and southern parts of the North Island.[2]

The life history of this species is unknown as are the host species of its larvae. The adults of this species is on the wing in November and December.[2]

This species has been collected in shrubland habitats including Olearia shrubland.[2] Specimens have also been collected in dunes on the coast as well as inland volcanic dunes.[2]

This species has been classified as having the "At Risk, Naturally Uncommon" conservation status under the New Zealand Threat Classification System.[9]