Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Coleoptera
Family: Lucanidae
Genus: Mitophyllus
Species: M. irroratus
Binominal name: Mitophyllus irroratus
Synonyms: Ptilophyllum godeyi, Mitophyllus curvidens.

Mitophyllus irroratus is an endemic beetle species in the family of Lucanidae. The scientific name of the species was published for the first time in 1842 by Parry. This species is the most widespread lucanid beetle in New Zealand having been found in numerous North and South Island localities and in the northern half of Stewart Island, but not on the Chatham Islands. It is the only stag beetle known from the Kermadec Islands.

Mitophyllus irroratus is small stag beetle that has black and brown variegated pattern. The antennae are short with three prongs. The larvae and adults of this species are found in dead and rotten stems, branches and wood. Very little is known about the biology and life histories of the New Zealand stag beetles.

A photo of Mitophyllus irroratus. 
1-Mitophyllus irroratus .jpg 


There is another NZ stag beetle Mitophyllus arcuatus that looks very similar but can easily be identified by the differences in the shape of its mandibles. When Mitophyllus arcuatus mandibles are closed there is a circular a gap between them. Mitophyllus irroratus jaws close with a rectangular gap between the mandibles...
The differences between female’s mandibles of these two species are more subtle.
Male mandibles
Mandibiles stag beetles.jpg

Thanks to Wikipedia for text and information: