Hemiandrus is a genus of wētā in the familyAnostostomatidae. In New Zealand they are known as ground wētā due to their burrowing lifestyle. Hemiandrus wētā are nocturnal, and reside in these burrows during the day. Ground wētā seal the entrance of their burrow during the day with a soil plug or door so that their burrow is concealed. This genus was originally said to be distributed in Australia and New Zealand, however, with recent molecular genetic methods, this is under debate. Ground wētā adults are smaller than other types of wētā, with the unusual trait of having both long and short ovipositors, depending on the species. The name of this genus is said to come from this trait as hemi- mean half and -andrus means male, as the species where the female has a short ovipositor can sometimes be mistaken for a male. This genus has a diverse diet, depending on the species.
Taxonomy
The genus Hemiandrus was originally described by Kjell Ander in 1938. 10 undescribed species of this genus are said to be in Australia, however molecular analyses show that the two lineages genetically represent two separate lineages, therefore their Australasian distribution is under debate. Hemiandrus is however the most species rich genus of the New Zealand Anostostomatidae.
Morphology
The genus Hemiandrus has the smallest sized wētā, in terms of body size, with individuals ranging from 12-45 millimetres, and weighing 1-3 grams. These wētā have no tympanum, and instead are able to detect sound through their cuticle, which is adaptive for their underground lifestyle. Some species in this genus have unusually short ovipositors for being Orthopterans, the species with this morphological trait exhibit maternal care, which is uncommon as it occurs only in five families within the Orthopteraorder.
Diet
The diet of these wētā depends on the species, where H. maculifrons is carnivorous, H. maia is omnivorous, eating fruit and invertebrates. Other ground wētā species however have been shown to be mainly herbivorous, eating apricots and various grass species.
Distribution
Australia
New Zealand - 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, riverbeds, alpine herb fields, and suburban gardens. If this genus also occurs in Australia, then this is the only non-endemic genus of wētā in New Zealand.
''Hemiandrus'' in New Zealand
There are approximately 20 undescribed New Zealand species of this genus, with 14 described species. These species of Hemiandrus are eaten by native species such as the wattle birds, kiwi, but also by introduced species such as mice, stoats, and hedgehogs. Of the described species in this genus, half have a restricted range, but most are common and widespread, and are not thought to be endangered.
Synonymy
Zealandosandrus Salmon, 1950 was formerly considered to be a distinct genus.
