Landcare Research - Manaaki Whenua

Landcare-Research -Manaaki Whenua

FNZ 53 - Harpalini (Insecta: Coleoptera: Carabidae: Harpalinae) - Popular summary

Larochelle, A; Larivière, M-C 2005. Harpalini (Insecta: Coleoptera: Carabidae: Harpalinae). Fauna of New Zealand 53, 160 pages.
( ISSN 0111-5383 (print), ; no. 53. ISBN 0-478-09369-1 (print) ). Published 04 Jul 2005

Popular summary

Harpaline ground beetles

The tribe Harpalini belongs to the subfamily Harpalinae (Coleoptera: Carabidae), which contains over 19 000 taxa worldwide. Molecular sequence data indicate Harpalinae evolved in the Cretaceous Period (140–65 million years ago).

The Harpalini form a diverse group, including over 240 genera and subgenera, and approximately 2000 species distributed in all biogeographic regions of the world. The present faunal review records 20 genera and 57 species for New Zealand. This should constitute nearly all the fauna.

Compared with larger or warmer regions of the world, e.g., Australia, which has a largely undescribed fauna with over 160 known species, the New Zealand fauna may appear relatively small, but New Zealand is a very special place – a biodiversity ‘hot-spot’ – with 75% of species (42 out of 57 species) and 55% of genera (11 out of 20 genera) found nowhere else in the world. The remaining fauna that are not endemic to this country are made up of overseas species introduced mainly from Australia. No native species is shared with Australia, although three native genera occur on both sides of the Tasman Sea, which suggests the New Zealand harpaline lineages have evolved mostly in isolation following the breakup of eastern Gondwanaland.

Harpalini are rather stout-bodied ground beetles with relatively short mandibles and other appendages, and a body length of 3–20 mm. They are usually darkly coloured, have only one hair-bearing puncture above each eye, no such puncture at the posterior angles of the pronotum, and elytra that are rounded, not twisted, at the sides near the apex. Some species living in caves or exhibiting strong burrowing habits are characterised by paler bodies and reduced eyes.

As observed in many other carabids, harpaline ground beetles are taxonomically diverse, generally abundant in the field, and demonstrate ecological preferences and a flexible set of responses to environmental factors. Because of these features, the relative ease with which their populations may be sampled by reliable quantitative methods (e.g., pitfall-trapping), and their potential use as bioindicators and biocontrol agents, they represent an attractive study group for biologists investigating evolutionary and ecological hypotheses.

As a result, Harpalini are well represented in New Zealand entomological museums and collections – over 5000 specimens were studied for this project. But despite such high interest, no taxonomic revision of this group has been produced until now.

Before the present revision, 13 genera and 36 species of Harpalini were known from New Zealand, but the authors have found a number of species had been described more than once under different names, and 23 species and 5 genera are new to science.

The geographical distribution of native species was undocumented before this study. We now have a better knowledge of their distribution patterns. The authors have found, for example, that several species are restricted to specific areas of New Zealand – the South Island northwest and the far north of the New Zealand appearing to have been reservoirs, in geological time, of much of the genetic diversity in New Zealand Harpalini, with several species currently restricted to these regions. Of the two main islands of New Zealand, the North Island has the greatest number of species (35 compared with 31 for the South Island), and only 4 native species (Allocinopus sculpticollis, Triplosarus novaezelandiae, Syllectus anomalus, Euthenarus puncticollis) are shared between the two islands. Three genera (Gaioxenus, Parabaris, and Kupeharpalus) are found only on the North Island, whereas two genera (Hakaharpalus and the cave-dwelling Pholeodytes) are confined to the northwest of the South Island. Two genera are restricted to the Three Kings Islands (Maoriharpalus, Kiwiharpalus). There is no genus endemic to the Chatham Islands. Stewart Island also has no endemic taxa, but shares 2 native species: Triplosarus novaezelandiae (with North Island and South Island), Euthenarus brevicollis (with South Island).

Over 50% of native species (25 out of 42 species) are known from 10 populations or fewer. All but one of these very special species are new to science, and all are of potential conservation concern. They are usually taxonomically highly distinctive species with low dispersal power, often geographically localised in threatened habitats, and represented in collections by relatively few specimens collected over many decades, which may indicate rare or highly specialised species.

No formal detailed study of the natural history of individual species of New Zealand Harpalini has ever been conducted, although Larochelle and Larivière (2001, Fauna of New Zealand 43) summarised information available from the literature, material in entomological collections, personal communications from carabid collectors, and their own personal field observations.

Most native species are flightless, having vestigial membranous wings (reduced to small wing buds), and live within the confines of native habitats, mostly forests (especially along streams) and wet habitats, also tussock grasslands and caves. Most Harpalini species are moisture loving and live at the surface of the soil and in leaf litter; they also live in caves, and occasionally on plants and trees. Dispersal in most native species is achieved by running over the ground; most species are moderate runners, except for the long-legged, fast-running cave species (Syllectus, Pholeodytes). In general, Harpalini have relatively short legs and, sometimes, strongly reduced eyes, indicative of strong burrowing habits.

All adventive species are able to fly, having long or fully developed membranous wings, and live mostly in highly modified environments (often around human dwellings), except for Haplanister crypticus, which has also managed to invade native forests.

The collecting season of newly emerged adults suggests Harpalini species may mate in the spring or autumn. For most species, adults are active during all months of the year, but are generally less active during cooler months.

No data are available on the feeding preferences of Harpalini native to New Zealand. Larochelle (1990, Food of carabid beetles of the World) showed that on a world basis Harpalini feed on both animal and vegetable matter, but tend to favour the latter. The mandibles of Hakaharpalus, Kiwiharpalus, Syllectus, Pholeodytes, and Maoriharpalus are unusually long in native Harpalini, which may suggest a specialised type of feeding. In addition, the strongly notched labrum (upper mouth part at base of mandibles) of Maoriharpalus is reminiscent of, although not necessarily equivalent to, the condition observed in the tribe Licinini, where species feed on hard-bodied invertebrates, e.g., snails.

This faunal review was written with a wide audience in mind. It aims to provide an inventory of New Zealand taxa, a concise treatment of their taxonomy, easy-to-follow identification keys, and several illustrations and maps, as well as a summary of all available information on species distribution, ecology, biology, and dispersal power. It is one step in the authors’ goal to to reach an overall understanding of the carabid fauna within a reasonable time frame, and to make relatively large amounts of information available for practical use by a wide range of end-users. It is hoped this kind of faunal taxonomy will provide both a solid foundation for studies of other types and the baseline information required by systematists, identifiers, ecologists, and other biologists, as well as by biosecurity and conservation managers.