Landcare Research - Manaaki Whenua

Landcare-Research -Manaaki Whenua

Popular summary: English

Gibbs GW, Kristensen NP 2019. Mnesarchaeidae (Insecta: Lepidoptera: Hepialoidea). 78, 105 pages.
( ISSN 1179-7193 (online) ; no. 78. ISBN 978-0-947525-60-6 (print), ISBN 978-0-947525-61-3 (online) ). Published

From their superficial appearance, no one could possibly say that moths in the family Mnesarchaeidae deserve any special attention. They look like ordinary little brown moths and are found well away from the public gaze. Yet they rank as one of Aotearoa's natural treasures despite not even having a common name. This is due to their endemicity—being entirely restricted to New Zealand, without any close relatives overseas.

Apart from a batfly, a marine caddisfly family, and four rather obscure little insect families, New Zealand insects at family level are found throughout the world. Endemicity is not a visual character so the appearance of these moths is deceptive. Despite their ‘ordinary’ appearance, the species described here are on a par with the more familiar examples of endemic families such as our native frogs (Leiopelmatidae), kiwi (Apterygidae), kokako (Callaeatidae), rifleman (Acanthisittidae) and short-tailed bat (Mystacinidae).

As a result of this study, this moth family now contains two genera—Mnesarchaea and Mnesarchella. By 1930 seven species were known, thanks largely to the efforts of Alfred Philpott, who worked at the Cawthron Institute in Nelson. This situation persisted until the present revision was undertaken, one outcome of which has been the discovery of a cluster of seven cryptic species—i.e. species which all look deceptively similar. Now it is clear that we have at least 14 species, seven of which are described here for the first time. Unfortunately, accurate identification remains a job for the experts.

‘Mnesarchaeids' nearest living relatives are the large Hepialidae or ‘ghost moths’ which include the porina and puriri moths. These two families comprise the second rung of tongued-moth evolution in the family tree of moths and butterflies—nearly as primitive as you can be if you are a moth with a tongue! The only moths below them on the tree are eriocraniids in the northern hemisphere and the jaw-moths, which have to chew their food.

All mnesarchaeids are small with wingspans of 7–12 mm. They are found from October to March with a peak in December. The larvae require a lush green carpet of soft mosses and liverworts, amongst which they spin a silken tunnel system or ‘lair’ and eventually a cocoon for pupation. They eat almost any living plant tissue in that sward, except that of flowering plants (i.e. a diet of mosses, liverworts, fern spores, algae and fungi). The life cycle is one year with growth over autumn and winter to reach maturity in spring. Many interesting parallels between mnesarchaeid larvae and those of Hepialidae are discussed here.

No mnesarchaeid species is distributed New Zealand-wide. Each covers a discrete geographical area, some bounded by Cook Strait, others spanning the Strait as it if didn't exist. Offshore, they are known only from Hauturu (Little Barrier Island) and Aotea (Great Barrier Island).

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