''Geodorcus alsobius'', or Moehau stag beetle, is a large flightless species of

stag beetle Stag beetles are a family of about 1,200 species of beetles in the family Lucanidae, currently classified in four subfamilies.Smith, A.B.T. (2006). A review of the family-group names for the superfamily Scarabaeoidea (Coleoptera) with corrections ...

in the family Lucanidae. It is found only on Mt Moehau, the highest mountain in the

Moehau Range The Moehau Range is the northernmost range on the Coromandel Peninsula, extending from the settlement of Colville, New Zealand northwards to the tip of the peninsula. Mount Moehau is the highest point of the range, at 892m above sea level. Physica ...

on the Coromandel Peninsula in

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

Description

Moehau stag beetles range in length (including mandibles) from 21.0 to 27.0 mm (males) and from 21.0 to 23.7 mm (females). They demonstrate

sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...

. The exoskeleton ranges from dull to glossy. It is black in colour and is pitted throughout. Male specimens have an obvious depression on the head behind the large mandibles. The head is widest behind the eyes.

Setae In biology, setae (singular seta ; from the Latin word for "bristle") are any of a number of different bristle- or hair-like structures on living organisms. Animal setae Protostomes Annelid setae are stiff bristles present on the body. Th ...

on the elytra are small. Male mandibles are large and curved with an obvious mid dorsal horizontal tooth

Distribution

''Geodorcus alsobius'' has a very restricted range. This species is only found on Mt Moehau on the Coromandel Peninsula in New Zealand.

Habitat

Adult specimens of the Moehau stag beetle are found under wet rotten logs and rocks at altitudes between 760m and 840m. They are nocturnal and inactive during the day. Larvae have been found under decaying logs. They have been situated in the uppermost layer of soil under a log that was decaying, but had yet to become humus. The larvae occupied galleries in the rotting log that were larger than their diameter.

Diet

Larvae are presumed to eat the decaying logs in which they build galleries. Adults of this species have not been recorded feeding, but other ''Geodorcus'' species are known to feed on the sap of trees from their mouthpart anatomy.

Conservation

Introduced mammalian predators have co-existed with ''Geodorcus alsobius'' for many years. Goat control started in 1956 in the Moehau area. The

Department of Conservation An environmental ministry is a national or subnational government agency politically responsible for the environment and/or natural resources. Various other names are commonly used to identify such agencies, such as Ministry of the Environment ...

began possum control in 1988 and rat control in 2005. Goats were eradicated in 2007. Priorities for conservation of this species involves surveying Mt Moehau to obtain information on the distribution and population size. In 2012, the threat status of this species was upgraded from range restricted to nationally endangered.

References

{{Taxonbar, from=Q21265830 Beetles of New Zealand Endemic fauna of New Zealand Lucaninae Endangered biota of New Zealand Beetles described in 2007 Endemic insects of New Zealand