Ischalis fortinata

Ischalis fortinata is a species of moth in the family Geometridae. It was first described by Achille Guenée in 1868. This species is endemic to New Zealand and has been observed in both the North, South and Stewart Islands. The species inhabits native forest. The larval hosts of this species include Polystichum vestitum and Polystrichum richardii. Adults have been observed all year around but are most frequently seen from October to February.

Taxonomy

This species was first described by Achille Guenée in 1868 using a specimen collected by R. W. Fereday, in Canterbury, likely at Akaroa on the Banks Peninsula, and originally named the species Polygonia fortinata. In 1875 Cajetan von Felder & Alois Friedrich Rogenhofer, thinking they were describing a new species, tentatively named it as Caustaloma ziczac. This name was synonymised by Edward Meyrick in 1883. He placed the species in the genus Azelina. George Hudson discussed this species under this name in his 1928 book The butterflies and moths of New Zealand. In 1970 Robert W. Poole placed this species in the genus Ischalis. In 2004 this placement was confirmed. The male lectotype specimen is held at the Natural History Museum, London.

Description

Hudson describes the larva as follows:
The mature larva of this species is a reddish-brown colour, with greenish reddish mottling, has a hairy appearance, and is between 25 and 30 mm long. Along the back of the larva there is a black edged, brown line and a number of black and white marks on a number of segments.
Guenée described the adults of this species as follows:

Distribution

This species is endemic to New Zealand. It has been recorded on the North and South Islands and is abundant in native forest in the far south of the South Island.

Behaviour

Eggs of I. fortinata are laid on the leaves of its host species. The black hairs covering the larvae ensure that it is well camouflaged when sheltering under the leaves of its host plants. The larva, when mature, forms a thin cocoon on the fronds of its host plants and overwinters as a pupa. The adult moth can be observed all year around but is most frequently seen from October to February.

Habitat and hosts

This species can be found in native forest. The larval hosts of this species include Polystichum vestitum and Polystrichum richardii. The larvae feed all year round.