Hemiandrus is a genusofwētā in the familyAnostostomatidae. In New Zealand they are known as ground wētā due to their burrowing lifestyle.[1][2]Hemiandrus wētā are nocturnal,[3] and reside in these burrows during the day.[4] Ground wētā seal the entrance of their burrow during the day with a soil plug or door so that their burrow is concealed.[4] 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 either long or short ovipositors, depending on the species. The name of this genus comes from this trait[5]ashemi- 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.
The genus Hemiandrus was originally described by Kjell Ander in 1938.[6] 10 undescribed species of this genus are said to be in Australia,[7] however molecular analyses show that the two lineages genetically represent two separate lineages, therefore their Australasian distribution is under debate.[8]Hemiandrus is however the most species rich genus of the New Zealand Anostostomatidae.[7]
The genus Hemiandrus include the smallest wētā species, with adult individual body size no more than 7 millimetres,[7] and weighing less than a gram.[9] The largest Hemiandrus species has a body length of almost 30mm.[10] These wētā have no tympanum, and instead are able to detect sound through their cuticle, which is adaptive for their underground lifestyle.[2] Some species in this genus have unusually short ovipositors for Orthopterans, the species with this morphological trait exhibit maternal care,[4] which is uncommon as it occurs only in five families within the Orthoptera order.[11]
The diet of these wētā depends on the species, where H. maculifronsiscarnivorous,[12]H. maiaisomnivorous, eating fruit and invertebrates.[4][13] Other ground wētā species however have been shown to be mainly herbivorous, eating apricots and various grass species.[14]
New Zealand - This genus are found throughout the North and South Island, and even on some of the offshore islands of New Zealand.[7] (See distribution map http://wetageta.massey.ac.nz/Text%20files/groundweta.html). They are found in lowland forests, riverbeds, alpine herb fields, and suburban gardens.[4] If this genus also occurs in Australia (which there is debate about[8]), then this is the only non-endemic genus of wētā in New Zealand.[9]
Several Hemiandrus species have been recorded stridulating, despite lacking the tympanum 'ears' present in other wētā genera. The sounds produced are inaudible to humans and is detected through the cuticle.[2][17][18] Many of the 'short ovipositor' species have been found to exhibit maternal care with females laying eggs in their burrows and remaining with the eggs and even nymphs while they develop.[17][4][19]
^Ander, K (1938). "Diagnosen neuer Laubheuschrecken". Opuscula Entomologica. 3: 50–56.
^ abJohns, P. M. (1997). "The Gondwanaland Weta: Family Anostostomatidae (Formerly in Stenopelmatidae, Henicidae or Mimnermidae): Nomenclatural Problems, World Checklist, New Genera and Species". Journal of Orthoptera Research (6): 125–138. doi:10.2307/3503546. JSTOR3503546.
^ abcdeTaylor-Smith, B. L.; Trewick, S. A.; Morgan-Richards, M. (2016). "Three new ground wētā species and a redescription of". New Zealand Journal of Zoology. 43 (4): 363–383. doi:10.1080/03014223.2016.1205109. S2CID88565199.
^ abChappell, E. M.; Webb, D. S.; Tonkin, J. D. (2014). "Notes on sexual size dimorphism, sex ratio and movements of adult ground weta (Walker) (Orthoptera: Anostostomatidae)". New Zealand Entomologist. 37 (2): 83–92. doi:10.1080/00779962.2013.856377. S2CID4814697.
^Gwynne, D. T. (1995). "Phylogeny of the Ensifera (Orthoptera): A Hypothesis Supporting Multiple Origins of Acoustical Signalling, Complex Spermatophores and Maternal Care in Crickets, Katydids, and Weta". Journal of Orthoptera Research (4): 203–218. doi:10.2307/3503478. JSTOR3503478.
^Basri, W. M. (1978). The biology and economic impact of the weta, Hemiandrus sp. (Orthoptera : Stenopelmatidae) in an apricot orchard, Horotane Valley (Thesis). Christchurch, New Zealand: Lincoln College, University of Canterbury. hdl:10182/3201.
^Johns, P.M. 1997: The Gondwanaland weta: family Anostostomatidae (formerly in Stenopelmatidae, Henicidae or Mimnermidae): nomenclatural problems, world checklist, new genera and species. Journal of Orthoptera research, (6): 125-138.
^Monteith, G.B.; Field, L.H. 2001: Australian king crickets: distribution, habitats and biology (Orthoptera: Anostostomatidae). Pp. 79-94 in Field, L.H. (ed.) The biology of wetas, king crickets and their allies. CABI publishing.
^Wilson, D. J.; Lee, W. G. (2010). "Primary and secondary resource pulses in an alpine ecosystem: snow tussock grass ( spp.) flowering and house mouse ( ) populations in New Zealand". Wildlife Research. 37 (2): 89. doi:10.1071/WR09118.
^Smith, D. H. V.; Jamieson, I. G.; Peach, R. M. E. (2005). "Importance of ground weta (Hemiandrus spp.) in stoat (Mustela erminea) diet in small montane valleys and alpine grasslands". New Zealand Journal of Ecology. 29 (2): 207–214. JSTOR24058176.
^Jones, C.; Moss, K.; Sanders, M. (2005). "Diet of hedgehogs (Erinaceus europaeus) in the upper Waitaki Basin, New Zealand: Implications for conservation". New Zealand Journal of Ecology. 29 (1): 29–35. JSTOR24056190.
