| Helms's stag beetle | |
|---|---|
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Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Coleoptera |
| Family: | Lucanidae |
| Genus: | Geodorcus |
| Species: | G. helmsi |
| Binomial name | |
| Geodorcus helmsi | |
| Synonyms [2] | |
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Geodorcus helmsi, known as New Zealand giant stag beetle or Helms's stag beetle, is a large, slow-moving, flightless stag beetle in the family Lucanidae. [3] It is endemic to New Zealand.
Geodorcus helmsi is a large flightless stag beetle that varies in colour from black to brownish-black. Its dorsal surface can vary from dull to glossy. Like other stag beetles, they show sexual dimorphism: males range in size from 17.5–44.0 mm, including their large mandibles, while females are smaller (16.5–27.5 mm) with less conspicuous mandibles. [4] In larger male specimens, the mandibles are long, slender and strongly arched with a conspicuous tooth near their base. G. helmsi is distinguished from other Geodorcus by its straight un-arched tibiae, and five setose ridges on the elytra. [5]
Geodorcus helmsi is the most widespread of the ten Geodorcus species, having been collected from Karamea on the northern West Coast of New Zealand to the south of the South Island, as far as Tapanui in West Otago. It has also been collected from islands in Fiordland and from Stewart Island. Adults have a wide altitudinal range, from sea level to 1400 m. [5] [6]
All Geodorcus species are mainly nocturnal and hide underneath fallen log stones or leaf litter on the forest floor. [7] At night G. helmsi have been seen active on tree trunks, chewing at the bark to get access to the exudate. This species occupies a highly variable habitat, including forest and tussock-dominated high country. [7]
The feeding ecology of adult G. helmsi may be highly variable: they occupy a wide range of habitats from forest to the tussock zone in the high country. Adults have been observed on tree trunks feeding on sappy exudate from wounds in the bark. [7] Larvae of other lucanid beetles commonly eat the surface of rotting wood. Geodorcus larvae have been observed to have large quantities of humus inside their gut. [5]
In New Zealand stag beetles, there is no published information about the duration or timing of oviposition, larval, pupal and adult stages of the life cycle. Copulation has been observed in October. [5] Larvae of Geodorcus have been seen under decaying logs, occupying a gallery in the soil layer. They are C-shaped, slow moving, and avoid the light. [7]
All Geodorcus species are protected under Schedule 7 of The 1953 Wildlife Act, making it illegal to hunt, kill, or possess a specimen. [8] Predation by introduced rats has reduced the population density of G. helmsi; on islands where rats are present, only their remains can be found. [5] On Rakiura (Stewart Island) rats eat more male Geodorcus helmsi than female specimens and the surviving individuals are significantly smaller than those killed by rats. [4] This species has been found to make up to 27% of the dry weight of feral pig stomach contents. [9]
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.
Lucanus cervus, known as the European stag beetle, or the greater 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.
Lucanus capreolus, the reddish-brown stag beetle or pinching beetle, is a beetle of the family Lucanidae. The specific name capreolus is derived from Latin, meaning "roe deer". The name refers to the resemblance of the mandibles to deer antlers.
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.
Cyclommatus is a genus of the family Lucanidae, also known as the stag beetle. The majority of the species from the genus Cyclommatus are located in Southeast Asia, though some species are found in China and Taiwan as well. The genus Cyclommatus also consists of three subgenera: Cyclommatus, Cyclommatinus and Cyclommatellus. Each subgenera contains 80, 24 and 3 species respectively. In total, the genus Cyclommatus consists of a total of 134 species, though more are still being discovered to this day.
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.
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.
Geodorcus capito is a large flightless species of stag beetle in the family Lucanidae. It is endemic to the Chatham Islands in New Zealand.
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.
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.
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.
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.
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.
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".
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. This holotype specimen is held in the New Zealand Arthropod Collection. It was first described by Beverley Holloway in 2007. The name sororum is translated from Latin to mean "belonging to the sisters".
Lyperobius huttoni is a New Zealand weevil found in alpine areas of the South Island and at sea level around the Wellington coast. It feeds only on speargrass (Aciphylla). Weevils from the endangered Wellington population have been translocated to predator-free Mana Island.
Dorcus hopei is a beetle in the family Lucanidae.
Figulus is a genus of beetle in the family Lucanidae. They have a paleotropical distribution, including occurrences in Australia.
