Geodorcus auriculatus

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 auriculatus
Female, illustrated by Des Helmore
Male, illustrated by Des Helmore
Conservation status
Sparse (NZ TCS)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Coleoptera
Suborder:	Polyphaga
Infraorder:	Scarabaeiformia
Family:	Lucanidae
Genus:	Geodorcus
Species:	G. auriculatus
Binomial name
Geodorcus auriculatus (Broun, 1903)[2]
Synonyms
Lissotes auriculatus Broun, 1903[2] Dorcus auriculatus Holloway 1961[3]

Description

G. auriculatus observed on Mt. Te Aroha

Geodorcus auriculatus are large dull to glossy black or brownish black beetles. Their exoskeleton is covered in dots and minute hairs with four inconspicuous ribs. The length for male specimens ranges from 21 to 29 mm. This length includes their impressive mandibles. Female beetles have much less variation in their size, ranging in length from 19–20 mm. Their smaller mandibles allow them to be distinguished from male beetles. Their head is widest behind the eyes and distinctly depressed and smooth in males, less so in female beetles.^[3]

Distribution

Geodorcus auriculatus is found from Manaia on the western side of the Coromandel Peninsula to Mount Te Aroha in the Kaimai range, south of the Coromandel. They can be found from near sea level to 950m on Mount Te Aroha.^[3]

Habitat and diet

Adult beetles have been found under fallen logs in the moist layer of decaying wood between a log and the soil underneath it. Forest types vary and include canopies of tawa, rimu, northern rātā, kauri, red and hard beech.^[4] Like other Geodorcus species G. auriculatus spends its entire life in cool damp environments such as under logs and rocks, emerging at night to feed on sappy exudations from trees or other plants.^[3]

Conservation

Like all Geodorcus species, G. auricualtus is protected under Schedule 7 of The 1953 Wildlife Act, making it an offense to hunt, kill or possess a specimen.^[5] The known range of this species has been greatly extended by repeated surveys by the Department of Conservation. The surveys followed it gaining the conservation status of 'endangered' to give it legal protection from collectors. Like other Geodorcus species that live on the North or South Island of New Zealand, rats possums and pigs are threats to the species as prey or to its habitat.^[3] Habitat loss by deforestation for logging or mining has also caused a loss of all beetle fauna within this species range.^[4]