Anderus is a genus of forest insects in the family Anostostomatidae (wÃÂtÃÂ). All Anderus species are nocturnal, and hide in burrows during the day. In New Zealand they are known as ground wÃÂtÃÂ due to their burrowing lifestyle. Ground wÃÂtÃÂ adults are smaller than other types of wÃÂtÃÂ, and females of all Anderus species have long ovipositors.
The genus Anderus was named for the Swedish entomologist Kjell Ander in 2024. Six species previously in the genus Hemiandrus were shown to be sister the Australian winged species Transaevum laudatum, based on analysis of DNA sequences. In the genus Anderus there are eight described species.
The genus Anderus includes the smallest wÃÂtÃÂ species, with adult individual body size no more than 7 millimetres, and weighing less than a gram. These wÃÂtÃÂ have no tympanum, and instead are able to detect sound through their cuticle, which is adaptive for their underground lifestyle. Species in the genus Anderus can be distinguished from other New Zealand ground wÃÂtÃÂ (Hemiandrus) using the covering of short fine setae over the whole of the surface of segment 4 of their maxillary palps.
Ground wÃÂtÃÂ seal the entrance of their burrow during the day with a soil plug or door so that their burrow is concealed. The diet of three species is dominated by invertebrate material; A. maculifrons, A. nox and A. subantarcticus are all carnivorous
Several ground wÃÂtÃÂ species have been recorded drumming, despite lacking the tympanum 'ears' present in other wÃÂtÃÂ genera. The sounds produced are inaudible to humans and is detected through the cuticle.
The species of Anderus are eaten by native bird species such as robins, saddlebacks kiwi, but also by introduced species such as mice, stoats, cats, and hedgehogs. Most species are common and widespread in native forests, and are not thought to be endangered (as per the New Zealand Department of Conservation).
Species of this genus are found throughout the North and South Island, and even on some of the offshore islands of New Zealand. They are found in lowland forests.