Cromwell chafer (Prodontria lewisi)

Description

Cromwell chafer fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
• Print factsheet

Cromwell chafer description

The Cromwell chafer is a Critically Endangered beetle found at just one site in Cromwell, New Zealand. It is a flightless beetle that belongs to the same family as dung beetles. This large beetle has pale reddish-brown wing cases (elytra) which are strongly convex and feature deep lines passing along their length. Females are longer and wider than males, but males have longer lower legs (tibiae) and larger hind feet ⁽²⁾.

Size

Length: 15 - 16 mm ⁽²⁾

Width: 8.5 mm ⁽²⁾

Cromwell chafer biology

The Cromwell chafer is a nocturnal species, active during the spring and summer from August to March. It emerges at night to feed on speedwell (Veronica arvensis), cushion plant (Raoulia australis), sheep's sorrel (Rumex acetosella) and a number of lichens ⁽²⁾. Activity is highest on warm nights when humidity is low, and they tend not to emerge if the temperature is below six degrees Celsius. ⁽²⁾. In the day, adults burrow up to half a metre deep in the soil, typically at the base of silver tussock (Poa cita); they tend to return to the same burrow that they used the previous day ⁽²⁾. Studies have shown that females do not disperse, but it is the males that wander in search of females to mate with. Males also tend to emerge earlier in the year than females ⁽³⁾

Very little is known of the larval stage of this beetle. It is thought that they may be associated with the roots of silver tussock, and that they may take more than one year to develop. Pupae of this species have never been found ⁽³⁾.

Cromwell chafer range

This beetle is endemic to New Zealand, where it is found at just one site near Cromwell in Central Otago, on the South Island ⁽³⁾. This 81 hectare area became the Cromwell Chafer Beetle Nature Reserve in 1983 ⁽³⁾. Within this site, just four discrete populations are known ⁽²⁾.

Cromwell chafer habitat

This beetle is found in an area of windblown sand dunes, beneath which there is a bed of gravel. Six vegetation types have been found in the area ⁽³⁾. The beetle is associated with scabweeds (Raoulia species) and silver tussock (Poa laevis) ⁽⁴⁾. The vegetation cover is dynamic, as there is heavy grazing by rabbits ⁽³⁾.

Cromwell chafer status

Classified as Critically Endangered (CR) by the IUCN Red List 2007 ⁽¹⁾.

Cromwell chafer threats

The original range of the Cromwell chafer was around 500 hectares, but this was reduced to just 100 hectares following the construction of the Clyde Dam and the expansion of the township of Cromwell ⁽⁴⁾. Threats facing this species are not fully understood, but are thought to include predation by introduced hedgehogs (Erinaceus europaeus). The little owl (Athene noctua) is also known to predate upon this species ⁽³⁾. Habitat alteration is also likely to be a problem ⁽²⁾. At the present time, large areas of apparently suitable habitat are not occupied by this beetle. It is imperative that the reasons for its present distribution and the factors limiting the population are understood ⁽³⁾.

Cromwell chafer conservation

The site supporting this species has been fully protected since it became a nature reserve in 1983. Research and monitoring of the Cromwell chafer populations are on-going, and current work is focusing on the predation risk posed by hedgehogs and other predators, potential competitors, and understanding the life history of the species ⁽³⁾. Hopes are that the knowledge gained from these studies will help to develop and guide the effective conservation of this unique and very rare beetle.

View information on this species at the UNEP World Conservation Monitoring Centre.

Find out more

For more information on the Cromwell chafer see:

• Ferreira, S. M. and McKinlay, B. (1999) Conservation monitoring of the Cromwell chafer beetle (Prodontria lewisii) between 1986 and 1997. Science for Conservation 123. Department of Conservation, Wellington, N.Z.
  http://www.doc.govt.nz/upload/documents/science-and-technical/sfc123.pdf

Authentication

Glossary

Endemic

A species or taxonomic group that is only found in one particular country or geographic area.

Larval stage

Stage in an animal’s lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.

Nocturnal

Active at night.

Pupae

Stage in an insect’s development when huge changes occur, which reorganise the larval form into the adult form. In butterflies the pupa is also called a chrysalis.

References

1. IUCN Red List (February, 2008)
   http://www.iucnredlist.org
2. New Zealand Department of Conservation: Beetles- scarabs and staphylinids. Scarab beetles: dung beetles, chafer beetles (February, 2008)
   http://www.doc.govt.nz/upload/documents/conservation/native-animals/invertebrates/014-beetles-scarabs-and-staphylinids.pdf
3. Ferreira, S.M. and McKinlay, B. (1999) Conservation monitoring of the Cromwell chafer beetle (Prodontria lewisii) between 1986 and 1997. Science for Conservation 123. Department of Conservation, Wellington, N.Z. Available at:
   http://www.doc.govt.nz/upload/documents/science-and-technical/sfc123.pdf
4. The State of Our Invertebrate Animals. New Zealand Ministry of the Environment (March, 2004)
   http://www.mfe.govt.nz/publications/ser/ser1997/html/chapter9.7.2.html