Biology:Geodorcus novaezealandiae

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Short description: Species of beetle

Geodorcus novaezealandiae
The upper surface of a black coloured beetle with dirt covering much of its body, particularly the head and abdomen
Female
The supper surface of a stout looking, black coloured beetle. The entire surface is covered in tiny pale dents
Male

Naturally Uncommon (NZ TCS)
Scientific classification edit
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Coleoptera
Family: Lucanidae
Genus: Geodorcus
Species:
G. novaezealandiae
Binomial name
Geodorcus novaezealandiae
(Hope, 1845)
Synonyms

Geodorcus novaezealandiae is a large species of stag beetle only found in the Wellington region of New Zealand. It was first described in 1845 by English entomologist Frederick William Hope. It is the smallest member of the genus Geodorcus, all of which are legally protected species. The species displays sexual dimorphism, with the male having distinctly larger and bulkier mandibles than the female. It is often found living under rimu (Dacrydium cupressinum) and southern beech (Nothofagus) trees. Like other Geodorcus species, the larva feeds on rotting wood whereas the adult is presumed to feed on plant sap. It has been speculated that both the male and female work together to create tunnels inside rotting wood to lay eggs in. Under the New Zealand Threat Classification System it is listed as "Naturally Uncommon" with the qualifier of "Range Restricted".

Taxonomy

G. novaezealandiae was first described in 1845 as Lucanus novaezealandiae by English entomologist Frederick William Hope.[1] The species was described again as Dorcus punctulatus in 1846 by Adam White, then as Sclerostomus caviceps by John Westwood and then once more in 1881 as Dorcus abditus by Thomas Broun.[2][3][4] Of these, S. caviceps and D. punctulatus were recognised to be L. novaezealandiae in 1868 whereas D. abditus was recognised as L. novaezealandiae in 1961.[5][6] The species has undergone numerous descriptions and been shifted between genera a few times, but was most recently revised in 2007 by New Zealand entomologist Beverly Holloway, who placed it in the genus Geodorcus, of which it is the type species. Four lectotypes (specimens chosen to serve as the type specimen when the original describer did not assign one) have been designated for this species and are in the Hope Department Collection at Oxford University and in the Natural History Museum of London.[6]

Description

Including their mandibles, the male is 12–21.5 mm in length whereas the female is 11–17.4 mm, which makes them the smallest species of Geodorcus. Like all other Geodorcus, they show sexual dimorphism: the male has a much wider head and larger mandibles whereas the female mandibles are relatively short and are less apparent. In the male, the front of the pronotum (the upper part of the thorax) bulges forwards and slightly hangs over the head whereas in female the pronotum is normal. The body is dull to slightly glossy black, with the upper surface being covered in small punctures. The elytra (hardened plates that cover the abdomen) have a series of slightly raised ribs running down their surface towards the tip of the elytra. The frons and vertex, which make up the front parts of the head, have a distinct depression. [7]

Distribution and habitat

G. novaezealandiae is only found in New Zealand, where it is found in the south of the North Island. Its range extends from the Akatarawa Valley in the Tararua Range in the north of the region to the Aorangi Range in the south. It has been observed at altitudes from near sea level to 365 m. It has been observed under the bark of live rimu (Dacrydium cupressinum) and southern beech (Nothofagus) trees. It's also been found in old beech stumps and amongst roots. Like other Geodorcus species, it is forest-dwelling and nocturnal.[7] Specimens have also been collected in traps 1.5 m above the ground on māhoe (Melicytus ramiflorus) and hinau (Elaeocarpus dentatus) trees.[8] In one study, pitfall traps were able to collect adults in winter, spring and summer whereas a revision of the species had specimens collected from July to April.[9][7]

Ecology and behaviour

As adults, it is presumed to feed on plant sap from the trees they hide in.[6] It has been reported feeding on speargrass (Aciphylla) and on pieces of apple (when held in captivity). Like other Geodorcus species, the larvae feed on rotting wood.[7] It has been speculated that both sexes work together to create tunnels in rotting wood to lay eggs in, with the male's large mandibles being well suited for the task. While copulating, the male and female face opposite directions with the tips of their abdomen touching.[6]

Conservation status

All Geodorcus species are protected under Schedule 7 of the 1953 Wildlife Act, making it an offense to possess, harm or sell these beetles.[10] Under the New Zealand Threat Classification System, it has a conservation status of "Naturally Uncommon" with the qualifier of "Range Restricted".[11]

References

  1. Hope, Frederick W (1845). A catalogue of the lucanoid Coleoptera in the collection of the Rev. F. W. Hope together with descriptions of the new species therein contained. London: J. C. Bridgewater. p. 25. https://archive.org/details/rcin.org.pl.WA488_168421_19746_s2035_133794/page/24/mode/2up. 
  2. White, Adam (1846). "Insects of New Zealand". The zoology of the voyage of H.M.S. Erebus and Terror. 2. p. 9. doi:10.5962/bhl.title.7364. https://www.biodiversitylibrary.org/page/6963006. Retrieved 16 January 2026. 
  3. Westwood, John O (1855). "Descriptions of some new species of exotic Lucanidae". Transactions of the Entomological Society of London 1855: 197–221. https://www.biodiversitylibrary.org/page/30707702. Retrieved 16 January 2026. 
  4. Broun, Thomas (1880). Manual of the New Zealand Coleoptera. Wellington: Printed at the Office of James Hughes, Lambton Quay. pp. 673–674. doi:10.5962/t.173101. https://www.biodiversitylibrary.org/page/60235524. Retrieved 16 January 2026. 
  5. Gemminger, Max; Harold, Edgar von (1868). Catalogus coleopterorum hucusque descriptorum synonymicus et systematicus. Monachii: sumptu E.H. Gummi. p. 963. doi:10.5962/bhl.title.9089. https://www.biodiversitylibrary.org/bibliography/9089. Retrieved 16 January 2026. 
  6. 6.0 6.1 6.2 6.3 Holloway, Beverley A (1961). "A systematic revision of the New Zealand Lucanidae (Insecta: Coleoptera)". Bulletin of the Dominion Museum, Wellington 20: 22–25. https://bugz.ento.org.nz/detail/3860d67a-1c1e-4e55-b5de-9cda4a7448d4. 
  7. 7.0 7.1 7.2 7.3 Holloway, Beverley A (21 November 2007). "Lucanidae (Insecta: Coleoptera)" (in en). Fauna of New Zealand 61: 93–95. doi:10.7931/J2/FNZ.61. ISSN 1179-7193. https://www.biotaxa.org/fnz/article/view/fnz.61. Retrieved 15 January 2026. 
  8. Moeed, Abdul; Meads, Mike J (1983). "Invertebrate fauna of 4 tree species in Orongorongo Valley, New Zealand, as revealed by trunk traps". New Zealand Journal of Ecology 6: 52. https://newzealandecology.org/nzje/1570. Retrieved 15 January 2026. 
  9. Moeed, Abdul; Meads, Mike J (1985). "Seasonality of pitfall trapped invertebrates in three types of native forest, Orongorongo Valley, New Zealand" (in en). New Zealand Journal of Zoology 12 (1): 7. doi:10.1080/03014223.1985.10428264. ISSN 0301-4223. Bibcode1985NZJZ...12...17M. http://www.tandfonline.com/doi/abs/10.1080/03014223.1985.10428264. Retrieved 15 January 2026. 
  10. "Wildlife Act 1953". Parliamentary Counsel Office. http://www.legislation.govt.nz/act/public/1953/0031/latest/whole.html#DLM277090. Retrieved 12 July 2017. 
  11. Leschen, Richard A B; Marris, John W M; Emberson, Rowan M; Nunn, John; Hitchmough, Rod A; Stringer, Ian A N (21 June 2012). "The conservation status of New Zealand Coleoptera" (in en). New Zealand Entomologist 35 (2): 91–98. doi:10.1080/00779962.2012.686311. Bibcode2012NZEnt..35...91L. https://www.tandfonline.com/doi/epdf/10.1080/00779962.2012.686311?needAccess=true. 

Wikidata ☰ Q21265838 entry