New Zealand ground wētā (Anostostomatidae:Hemiandrus): descriptions of two species with notes on their biology

Abstract

Although the New Zealand ground wētā (Anostostomatidae: Hemiandrus) are widespread and abundant, little has been described of their ecology and behaviour. Within the genus several lineages have evolved with ovipositors that are unusually short for this orthopteran family. Some species with this derived morphological character also exhibit maternal care of eggs and offspring. Two new species are described here, Hemiandrus maia sp. nov. and Hemiandrus electra sp. nov. Although morphologically similar with medium length ovipositors, they are not sister taxa and live at opposite ends of South Island, New Zealand. The behaviour of Hemiandrus maia sp. nov. was studied using burrow door re-construction as a key to activity patterns. Observations at night and burrow excavation during the day were used to identify features of their behaviour. Maternal care of both eggs and nymphs was observed. Hemiandrus maia sp. nov. were shown to eat fruit, invertebrates and seeds without discrimination.http://zoobank.org/urn:lsid:zoobank.org:pub:1C7EB0D2-D01B-4D3A-B643-D17813EC2084

Ground wētā in vines of the Awatere Valley, Marlborough: biology, density and distribution

“…But the conversion of these lands from paddocks and/or shrublands (Gillingham 2012) to vineyards does not seem to have adversely affected their survival. This is because the estimated population size for this wētā was higher than the 1.8/m 2 and 3.0/m 2 reported for the ground wētā H. maia Taylor Smith, 2013and H. electra Taylor Smith, 2013, respectively, in non-agricultural lands (Taylor Smith et al 2013. Given the size of the population and the significant damage on vines, this species can be considered as a pest in the Awatere Valley vineyards.…”

“…However, most wētā species in the genus Hemiandrus Ander, 1938 were classified as having an Indeterminate conservation status because of the paucity of information on their biology, density and distribution (Sherley 1998;Johns 2001). Hemiandrus comprises approximately 40 species, which are referred to as 'ground wētā', but only 11 of these have been described to date (Johns 1997(Johns , 2001Jewell 2007;Taylor Smith et al 2013). Each of the species in this genus is found at specific locations in the North and South Islands of New Zealand, although some species, such as H. maculifrons (Walker, 1869), occur on both islands (Pratt et al 2008;Chappell et al 2012).…”

A preliminary survey of altitudinal variation in two ground wētā species,Hemiandrus maculifrons(Walker) andHemiandrus pallitarsis(Walker) (Orthoptera: Anostostomatidae)

“…Ground wētā in the genus Hemiandrus (Orthoptera: Anostostomatidae) have 11 described species and approximately 30 undescribed species in New Zealand (Johns 1997(Johns , 2001Jewell 2007;Taylor Smith et al 2013). They are nocturnal, burrowing, flightless insects that range in body size from 12 to 45 mm, and occur throughout the New Zealand archipelago (Johns 2001;Pratt et al 2008).…”

The complex tibial organ of the New Zealand ground weta: sensory adaptations for vibrational signal detection

“…All New Zealand species of Hemiandrus ground weta lack tympanal hearing organs typical in other Ensifera and are presumed to be insensitive to far-field airborne sound 7, 15 . While sensory hairs on the insect body surface may also respond to substrate vibrations 16, 17 or airborne sound, their response is restricted to near-field sound 18, 19 or air-currents 20 .…”

“…Ground weta burrow in the soil but abdominal drumming for mate attraction and mating occurs mainly on leaves of shrubs or ferns which transmit the vibrations 12 . The temporal patterns have been compared for selected species but the frequency characteristics, signal amplitudes or signaling range in the vegetation are so far not documented 12, 15 . In addition, males may use vibrational signals to defend territories around their burrows in the soil 7 .…”