|Poor Knights giant weta, Deinacrida fallai
Overall length 20 cm (8 in)
|Subfamilies and genera|
Anostostomatidae is a family in the order Orthoptera. It is sometimes referred to as Mimnermidae or Henicidae in some taxonomies, and common names include King crickets in South Africa, and weta in New Zealand. They are believed to be most closely related to the Jerusalem crickets of North America. Prominent members includes the Parktown prawn of South Africa, and the giant weta of New Zealand. The cave weta belong to another family, the Rhaphidophoridae. Their distribution reflects a common ancestry before the fragmenting of Gondwana.
By virtue of their ability to cope with variations in temperature, members of the Anostostomatidae family can be found in a variety of environments including alpine, forests, grasslands, shrub lands and urban gardens. The family is widely distributed across southern hemisphere lands including South America, Australia, South Africa and New Zealand. They are nocturnal and many are flightless although several flying species exist in Australia. The diet is diverse, rarely consisting of leaves, and more commonly a combination of other insects, fungi, dead animals, and fruit. An Australian king cricket can overpower and eat funnel-web spiders.
Taxonomy and evolution
At least one Cretaceous fossil of an anostostomatid-like cricket is known from Australia but has not been described. The modern distribution of this family on lands in the southern hemisphere has led to speculation that members of this group owe their distribution to the breakup of the ancient supercontinent Gondwana. This may be the case but evidence for the large scale if not total submergence of continental crust in the New Zealand and New Caledonian region in the Oligocene, indicates the possibility that weta have arrived in these locations at least, since re-emergence of land. The fact that anostostomatid crickets also occur on some Japanese islands supports this possibility.
The King Crickets or Koringkrieke of South Africa
There are some two dozen species of these armoured ground crickets in Africa, and they are widespread and common in drier areas. Mostly nocturnal, they are alike in habits and robust appearance, their differences being mainly in their size and the arrangement of their spiny armour. All may squirt a smelly fluid from the thorax if roughly handled, and can inflict a sharp, non-poisonous bite. They shuffle along rather clumsily and are incapable of flight, though males do retain stubby wings under the shield on the thorax and produce a rasping noise by rubbing these together rapidly. They may also make a noise by rubbing their mandibles against their second set of jaws. Females have a conspicuous ovipositor consisting of a number of slender blades, pressed together to form a flattened tube. Males often sport an enormous pair of mandibles which can pack a powerful pinch.
Henicus monstrosus is a nocturnal armoured ground cricket of unusual appearance, having an oversized head with forward-directed prongs and an extremely long, curved pair of jaws which - though functional - seem to play no part in the eating process.
The weta of New Zealand
New Zealand had no native land mammals apart from native bats immediately before humans arrived, but Miocene fossils indicate terrestrial mammals probably existed at that time. In New Zealand, anostostomatid crickets (weta) are ecologically diverse and occupy a wide range of habitat types. Some genera are primarily predators or scavenger, whilst others - notably the so-called tree weta Hemideina and their close relatives the giant weta Deinacrida - can bite. Tree weta bites are not particularly common. They can also inflict painful scratches with the potential of infection. Weta are known to arc their hind legs into the air in warning to foes and use acoustic communication (stridulation) to signal to one another .
The five weta groups in New Zealand
- Giant weta
- Tree weta
- Tusked weta and Northland tusked weta
- Ground weta
- Cave weta (in another family)
Subfamilies and genera
- Subfamily Anostostomatinae Saussure, 1859
- Hemiandrus, ground weta
- Libanasidus, king crickets
- Motuweta, tusked weta
- Subfamily Deinacridinae
- Subfamily Leiomelinae
- 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. ISSN: 1082-6467 JSTOR
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