The New Zealand Coleorrhyncha (Insecta: Hemiptera)

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How to cite this publication
Larivière M-C, Larochelle A 2012-2015. The New Zealand Coleorrhyncha (Insecta: Hemiptera).

This introduction to New Zealand Peloridiidae updates the Popular Summary published on pages 5-6 of the Faunal review by Larivière, Burckhardt & Larochelle (2011).

The family Peloridiidae or moss bugs are primitive members of the insect order Hemiptera. These “living fossils”, as they are often called, belong to the surborder Coleorrhyncha and live in the wet moss of temperate and subantarctic rainforests.

Peloridiids occur in Chile, Argentina, New Zealand,New Caledonia, and eastern Australia, including Tasmania and Lord Howe Island, and are known from 17 genera and 36 species. Four genera and 14 species occur from New Zealand.

New Zealand can be regarded as a biodiversity ‘hotspot’ for these insects. Three of four genera and 13 of 14 species recorded from this country are endemic, meaning that they do not occur anywhere else. On a world basis New Zealand has the most diversified fauna at the species level, with 36% of all world species in this group of special significance for the Southern Hemisphere and evolutionary roots dating back to the break-up of Gondwana.

Moss bugs are strange-looking insects, generally ranging from 2 to 4 mm in length. Their body is flattened, broadly shaped, and cryptically coloured so that it blends with the surrounding environment. Their head is peculiar in that the eyes are widely separated, prominent at the sides, and petiolate (positioned on short stalks). The surface of their anterior or top wings is hardened and bears a network of veins and variously shaped areolae or closed cells.

All New Zealand species lack posterior wings and are flightless. They probably spend most of their life in the wet moss on which they feed, moving very little. It is thought that if environmental conditions become drier, peloridiids move deeper into the moss layers in search of moisture and remain there until it is again suitably wet nearer to the surface.

Little is known about the biology and behaviour of New Zealand moss bugs. The life-cycle of these insects includes the egg stage, five nymphal stages, and the adult stage: once the egg has matured it develops into a nymph that feeds and grows through five stages before it  finally becomes an adult. The adult stage occurs mostly from December to March. Newly emerged adults – more soft-bodied and lightly coloured than mature adults – are active in January (North Island) or February (South Island). Nymphs of various stages are often found with adults, from November to December (North Island) or from January to February (South Island). Field surveys conducted during the New Zealand winter (June to September) have yielded only a few mature adults; no newly emerged adults or nymphs have been found in that season. This suggests moss bugs spend the winter in the adult and/or the egg stage.

The geographical distribution of most New Zealand peloridiid species was poorly documented before 2011. We now have a better understanding of distribution patterns, but more collecting is needed in under-surveyed areas such as Northland, the Coromandel Peninsula, eastern parts of the South Island, the Chatham Islands, and Stewart Island.

The genera Xenophyes and Oiophysa occur on the North and South Islands, while the genus Xenophysella is shared between the South Island and Stewart Island, where the genus Oiophysa also occurs. The Australian genus Hemiodoecus is represented by one species, H. leai; it occurs on the South Island (Dunedin) and has probably been introduced from Tasmania (Wakelin & Larivière, 2014).

Of the two main islands of New Zealand, the South Island has the greatest number of indigenous genera (3) and species (10 or 77% of the indigenous fauna) although not all species are restricted to that island. Two moss bug species are shared between the North and South Islands, eight (8) indigenous species are restricted to the South Island, and two species to Stewart Island.