Geodorcus sororum

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Geodorcus sororum
Geodorcus sororum 131380652.jpg
Illustration by Des Helmore
Status NZTCS NC.svg
Nationally Critical (NZ TCS) [1]
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Coleoptera
Family: Lucanidae
Genus: Geodorcus
Species:
G. sororum
Binomial name
Geodorcus sororum
(Holloway, 2007) [2]

Geodorcus sororum is a large flightless species of stag beetle in the family Lucanidae. It was discovered in 1973 by Mr. A. Wright on an expedition to Middle Sister Island/Te Awanui, one of The Sisters Islands/Rangitatahi which are part of the Chatham Islands in New Zealand. [2] This holotype specimen is held in the New Zealand Arthropod Collection. [3] It was first described by Beverley Holloway in 2007. [2] The name sororum is translated from Latin to mean "belonging to the sisters". [2]

Contents

Description and taxonomy

Male (left) and female (right) pinned specimens, showing sexual dimorphism. Geodorcus sororum.jpg
Male (left) and female (right) pinned specimens, showing sexual dimorphism.

This beetle ranges in length (including mandibles) from 18.0 to 28.5 mm (males) and from 19.4 to 24 mm (females). It has a glossy exoskeleton which ranges in colour from reddish-black to black. Like Geodorcus servandus , its elytra are not distinctly ribbed. This is a feature that distinguishes G. sororum from G. capito which is also found in the Chatham Islands. They demonstrate sexual dimorphism with an overall size difference and obvious differences in mandible shape and size. [2] The two species of Geodorcus beetle on the Chatham Islands share a common ancestor. Mitochondrial DNA analysis shows that G. capito and G. sororum are more closely related than either is to the other Geodorcus species found on mainland New Zealand. Individuals of G. sororum are very closely related to each other and have low genetic diversity. [4]

Distribution

This species has only been observed on Middle Sister Island, which is located 19 km north-west of Chatham Island. Collections of the beetle have been made from near sea level to 40 m. [2] This island is a breeding ground for large seabirds including northern royal albatross and Buller's albatross. [5]

Habitat

Geodorcus sororum observed on via iNaturalist. Geodorcus sororum 131380652.jpg
Geodorcus sororum observed on via iNaturalist.

Middle Sister Island has sparse vegetation consisting mainly of coastal herbs and ice plant. [5] Other Geodorcus species are associated with rotten logs, but this habitat is absent from the treeless Sisters Islands, which are two pyramidical rocks about 100 feet high, covered with scanty bushes, and frequented by countless numbers of sea-birds. [6]

Diet

Geodorcus beetle larvae tend to feed on decaying wood or the fungi involved in decomposition. Geodorcus sororum larvae must consume an alternative, as the plant communities on Middle Sister Island consist only of small shrubs and herbs. The adult beetles must also consume an alternative food source to the other members of this genus, considering the absence of woody vegetation on this small island. [7] The presence of a humus-rich soil should allow this species to complete its life cycle. [4]

Conservation

Like all Geodorcus species, G. sororum is absolutely protected under Schedule 7 of The 1953 Wildlife Act, making it an offense to collect or harm a specimen. [8] It has a conservation status as nationally critical due to its small population on Middle Sister Island and presence in only one location. [1] The Sisters Islands are currently rodent free. They are visited by birdwatchers and the introduction of rodents would be catastrophic for this species. [2]

Related Research Articles

<span class="mw-page-title-main">Stag beetle</span> Family of insects

Stag beetles are a family of about 1,200 species of beetles in the family Lucanidae, currently classified in four subfamilies. Some species grow to over 12 centimetres, but most to about 5 cm (2 in).

The false stag beetles (Diphyllostoma) are a group of three species of rare beetles known only from California. Almost nothing is known of their life history beyond that the adults are diurnal and females are flightless; larvae have not been observed.

<span class="mw-page-title-main">The Sisters (New Zealand)</span>

The Sisters / Rangitatahi is a group of three islands located 16 kilometres (10 mi) north of Cape Pattison, Chatham Island. They are the northernmost members of the Chatham Archipelago, located 800 kilometres (497 mi) east of New Zealand's South Island.

<i>Lucanus cervus</i> Species of beetle

Lucanus cervus, the European stag beetle, is one of the best-known species of stag beetle in Western Europe, and is the eponymous example of the genus. L. cervus is listed as Near Threatened by the IUCN Red List.

<i>Chiasognathus grantii</i> Species of beetle

Chiasognathus grantii is a species of stag beetle found in Argentina and Chile. It is known as Darwin's beetle, Grant's stag beetle, or the Chilean stag beetle.

<i>Hexarthrius parryi</i> Species of beetle

Hexarthrius parryi, the fighting giant stag beetle, is a species of large stag beetles. It belongs to the genus Hexarthrius of the tribe Lucanini. It is classified under the subfamily Lucaninae of the stag beetle family Lucanidae.

<i>Paralissotes reticulatus</i> Species of beetle

Paralissotes reticulatus, also called the New Zealand reticulate stag beetle, is a native species of stag beetle from New Zealand. Although they do have wings they are flightless.

<i>Geodorcus helmsi</i> Species of beetle

Geodorcus helmsi,New Zealand giant stag beetle or Helms's stag beetle is a large, slow-moving, flightless stag beetle in the family Lucanidae. It is endemic to New Zealand.

<i>Amychus granulatus</i> Species of beetle

Amychus granulatus, commonly known as the Cook Strait click beetle, is a large flightless click beetle in the family Elateridae.

<i>Geodorcus</i> Genus of beetles

Geodorcus is a genus of beetles belonging to the family Lucanidae. They are endemic to New Zealand. All Geodorcus species are protected under Schedule 7 of The 1953 Wildlife Act, making it an offense to hunt, kill or possess a specimen.

<i>Geodorcus capito</i> Species of beetle

Geodorcus capito is a large flightless species of stag beetle in the family Lucanidae. It is endemic to the Chatham Islands in New Zealand.

<i>Geodorcus alsobius</i> Species of beetle

Geodorcus alsobius, or Moehau stag beetle, is a large flightless species of stag beetle in the family Lucanidae. It is found only on Mt Moehau, the highest mountain in the Moehau Range on the Coromandel Peninsula in New Zealand.

<i>Geodorcus auriculatus</i> Species of beetle

Geodorcus auriculatus is a large flightless stag beetle that is found in the southern part of the Coromandel Peninsula and on Mount Te Aroha in the Kaimai range of New Zealand.

<i>Geodorcus ithaginis</i> Species of beetle

Geodorcus ithaginis, the Mokohinau stag beetle, is a large flightless species of stag beetle in the family Lucanidae. It was described by Thomas Broun in 1893 after being discovered in the Mokohinau Islands by Andreas Stewart Sandager, a lighthouse keeper on the islands. The species survives only on the small unnamed island "Stack H", in a patch of vegetation the size of a living room, and is in extreme danger of extinction.

Geodorcus montivagus is a large flightless species of stag beetle in the family Lucanidae. It is known from only one female specimen found on the Victoria Range in New Zealand. It was found in tussock at 1,220 metres (4,000 ft) above sea level.

<i>Geodorcus novaezealandiae</i> Species of beetle

Geodorcus novaezealandiae is a large flightless species of stag beetle in the family Lucanidae. It is the type species and smallest member of the genus Geodorcus. It is endemic to New Zealand.

<i>Geodorcus philpotti</i> Species of beetle

Geodorcus philpotti is a large flightless species of stag beetle in the family Lucanidae. It was named by Major Thomas Broun after Mr A. Philpott, who discovered it at Hump Ridge near Invercargill. It is endemic to New Zealand.

<i>Geodorcus servandus</i> Species of beetle

Geodorcus servandus is a large flightless species of stag beetle in the family Lucanidae. It was discovered by P.R. Kettle in December 1960 and this holotype specimen is held in the New Zealand Arthropod Collection. It was first described by Beverley Holloway in 2007. Its type location is Mount Tuhua summit, near Lake Kaniere on the West Coast of New Zealand. The name servandus is a Latin word meaning "[something] to be preserved, conserved, looked after".

<i>Paralissotes</i> Genus of beetles

Paralissotes is a genus of stag beetle that are endemic to New Zealand.

<i>Aegus chelifer</i> Species of beetle

Aegus chelifer, is a species of stag beetle found in Indo-Malaya regional countries.

References

  1. 1 2 Leschen, R.A.B; Marris, J. W.M.; Emberson, R. M.; Nunn, J.; Hitchmough, R. A.; Stringer, I. A.N. (July 2012). "The conservation status of New Zealand Coleoptera". New Zealand Entomologist. 35 (2): 2. doi:10.1080/00779962.2012.686311. S2CID   219566068.
  2. 1 2 3 4 5 6 7 Holloway, B.A. "Lucanidae (Insecta: Coleoptera)" (PDF). Landcare New Zealand. Landcare Research. p. 99. Retrieved 24 July 2017.
  3. ↑ "Landcare Research" . Retrieved 4 June 2017.
  4. 1 2 Goldberg, J.; Trewick, S.A.. (2011). "Exploring Phylogeographic Congruence in a Continental Island System". Insects. 2 (3): 369–399. doi: 10.3390/insects2030369 . PMC   4553550 . PMID   26467734.
  5. 1 2 "Chatham Islands Conservation Management Strategy" (PDF). Department of Conservation. Department of Conservation. Retrieved 26 July 2017.
  6. ↑ Dieffenbach, Ernest (1841). "An Account of the Chatham Islands". The Journal of the Royal Geographical Society of London. 11: 195–215. doi:10.2307/1797646. JSTOR   1797646.
  7. ↑ Sherley, Greg; Green, Chris; Owen, Keith (1994). "Distribution, conservation status and some features of the natural history of Dorcus stag beetles (Coleoptera: Lucanidae)" (PDF). Science and Research Series (75). Retrieved 27 July 2017.
  8. ↑ "Wildlife Act 1953". New Zealand Legislation. Parliamentary Counsel Office. Retrieved 27 July 2016.
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