Landcare Research - Manaaki Whenua

Landcare-Research -Manaaki Whenua

FNZ 65 - Izatha (Insecta: Lepidoptera: Gelechioidea: Oecophoridae) - Abstract

Hoare, RJB 2010. Izatha (Insecta: Lepidoptera: Gelechioidea: Oeco­phoridae). Fauna of New Zealand 65, 201 pages.
( ISSN 0111-5383 (print), ISSN 1179-7193 (online) ; no. 65. ISBN 978-0-478-34724-1 (print) , ISBN 978-0-478-34725-8 (online) ). Published 02 Sep 2010


The endemic New Zealand genus Izatha Walker (Oecophoridae) is revised. Forty species are recognised, including the following 15 species described as new: Izatha blepharidota n. sp., I. dasydisca n. sp., I. dulcior n. sp., I. gekkonella n. sp., I. gibbsi n. sp., I. haumu n. sp., I. katadiktya n. sp., I. lignyarcha n. sp., I. minimira n. sp., I. notodoxa n. sp., I. quinquejacula n. sp., I. spheniscella n. sp., I. taingo n. sp., I. voluptuosa n. sp. and I. walkerae n. sp. Three new synonymies are established: Zirosaris amorbas Meyrick and Trachypepla amorbas Meyrick are sunk as junior subjective synonyms of I. copiosella (Walker) and I. plumbosa Philpott as a junior subjective synonym of I. mira Philpott. Izatha huttonii Butler is removed from synonymy with I. peroneanella (Walker), and I. acmonias Philpott from synonymy with I. picarella (Walker). Izatha griseata Hudson is removed from Oecophoridae and transferred to Gelechiidae as a junior subjective synonym of Anarsia dryinopa Lower. The adults of all species are described and illustrated in colour, along with the genitalia of both sexes, where known. Larvae are briefly described for all species for which positive associations have been made. Seven informal species-groups are recognised, based on characters of the head, wing pattern, and male and female genitalia.

The larvae of most species that have been reared feed in dead rotten wood, but the larvae of I. gekkonella n. sp. and probably I. convulsella (Walker) and I. phaeoptila (Meyrick) feed on lichens (and/or epiphytic mosses), and I. prasophyta Meyrick was once reared from a fruiting body of the bracket fungus Bjerkandera adusta. The systematic position of Izatha is discussed: it is assigned to the Hierodoris group of Hoare, and is considered most closely related to dead-wood feeding members of the genus Gymnobathra Meyrick, which is also endemic to New Zealand.The diversity and distribution patterns of Izatha are discussed. It is the second largest genus of true (i.e. non-pyraloid) Microlepidoptera in New Zealand after Tingena (Oecophoridae), though Stigmella (Nepticulidae) when revised will probably rival Izatha in diversity. Among New Zealand Lepidoptera genera containing over 30 species, Izatha is unique in having more species endemic to the North Island than to the South Island: 22 species are confined to the North Island (including offshore islands), 10 to the South Island, and 6 are shared between both islands; 2 further species are endemic to the subantarctic Snares Islands. This pattern of diversity is similar to that observed in other insect groups associated with dead wood and fungi in forest habitats, e.g., Aradidae (Hemiptera: Heteroptera), and may reflect the persistence of greater areas of forest refugia in the North Island (especially Northland) during the last glaciation.

Izatha displays remarkable diversity in the structure of the genitalia, and this is discussed with respect to sexual selection and sexually antagonistic coevolution. Males of many species have strongly spinose phalli, and there is evidence of corresponding damage to the female genital tract. Females of some species have the ductus bursae strongly reinforced with sclerotised scobinations. A group of 11 predominantly North Island species have deciduous cornuti in the male vesica, which are left behind in the female tract after mating; all cornuti are apparently committed to the first mating. From spermatophore counts, the females are known to mate up to 4 times.

Adult Izatha are cryptically patterned bark and/or lichen mimics. Most species have raised scale-tufts on labial palpi, legs, and forewings that enhance the crypsis; the forewing tufts consist of strongly curled scales. The shining leaden or golden iridescent undersides of the curled scales may further break up the pattern; the iridescence is due to the very fine corrugations of the lower scale lamina, which act as a diffraction grating.

Most species of Izatha are widespread, although some are known from very few localities. Species likely to be endemic to restricted areas are I. quinquejacula n.sp. (Three Kings Islands), I. haumu n. sp. and I. taingo n. sp. (Aupouri peninsula), I. dulcior n. sp. (Poor Knights Islands), and I. oleariae Dugdale and I. spheniscella n. sp. (Snares Islands). Three species are considered of immediate conservation concern: I. rigescens Meyrick, not collected since its discovery on the Wellington coast in 1929, I. psychra (Meyrick), currently only known from a single Mackenzie Country shrubland, which is vulnerable to fire and pine invasion, and I. caustopa (Meyrick), which has been seen only 3 times in the last 70 years, and may have been affected by the decline of its only known host tree, Fuchsia excorticata, due to attack by introduced possums.