''Isoplectron'' is a genus of cave

wētā Wētā (also spelled weta in English) is the common name for a group of about 100 insect species in the families Anostostomatidae and Rhaphidophoridae endemism, endemic to New Zealand. They are giant wingless insect, flightless cricket (insect ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Rhaphidophoridae The orthopteran family Rhaphidophoridae of the suborder Ensifera has a worldwide distribution. Common names for these insects include cave crickets, camel crickets, spider crickets (sometimes shortened to "criders" or "sprickets"), and sand trea ...

with eight species recognised. The genus is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to New Zealand and distributed throughout most of the country but has not been recorded north of Taupo.

Taxonomy and morphology

The genus ''Isoplectron'' was described by

Hutton Hutton may refer to: Places ;Antarctica * Hutton Cliffs, Ross Island * Hutton Mountains ;Australia * Hutton Sandstone Formation ;Canada * Hutton, Alberta, a locality * Hutton, British Columbia, a railway point * Hutton railway station, Brit ...

in 1896. All species in this genus are small in size (10-17mm body length) and are commonly misidentified. The fore femora of the ''Isoplectron'' does not contain apical spines, in addition, the hind tibiae models two pairs of apical spines. Adult females have a broad bilobed subgenital plate while males have a triangular shape. Five new species were described in 2024 and two species were moved from the genera ''Petrotettix'' and ''Setascutum''.

''Isoplectron armatum''

''Isoplectron armatum'' are the most commonly observed species of ''Isoplectron''. They are found across

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

with the subspecies ''I. a. armatum'' in

South Island The South Island ( , 'the waters of Pounamu, Greenstone') is the largest of the three major islands of New Zealand by surface area, the others being the smaller but more populous North Island and Stewart Island. It is bordered to the north by ...

and subspecies ''I. a. aciculatum'' in

North Island The North Island ( , 'the fish of Māui', historically New Ulster) is one of the two main islands of New Zealand, islands of New Zealand, separated from the larger but less populous South Island by Cook Strait. With an area of , it is the List ...

. These Rhaphidophoridae are arboreal and during the day can be found in dry spaces under bark or in holes of various trees, especially ''Nothofagus cliffortioides'' and kanuka and in artificial refugia (wētā boxes). They are also caught in pitfall traps in southern North Island forests. Their morphology consists of a body length between 11-17mm, short dorsal and laterals in the hind tibial apical spurs, a very small ventral pair of hind tibial apical spurs and no spinules in the hind tarsal plantulae. This is consistent across males and females. All adult males have a conspicuous curved spine on the retrolateral inferior edge of their hind femur.

''Isoplectron pallidum''

Described by

Aola Richards Aola Mary Richards (16 December 1927 – 2 November 2021) was a New Zealand entomologist specialising in the study of New Zealand and Australian cave crickets, or wētā (Rhaphidophoridae), and Australian ladybird beetles (Coccinellidae). She was ...

in 1972 from a single female specimen and moved from the genus ''Setascutum'' to ''Isoplectron'' in 2024. This is the smallest ''Isoplecton'' species. ''Isoplectron'' ''pallidum'' is found in sub alpine and alpine rock tors and in montane forest under bark in

Otago Otago (, ; ) is a regions of New Zealand, region of New Zealand located in the southern half of the South Island and administered by the Otago Regional Council. It has an area of approximately , making it the country's second largest local go ...

Species

* '' Isoplectron armatum'' ''armatum'' Hutton, 1897 * '' Isoplectron armatum aciculatum'' Karny, 1937 * ''Isoplectron bicolor'' Hegg, Morgan-Richards & Trewick, 2024 * '' Isoplectron ferratum'' Hegg, Morgan-Richards & Trewick, 2024 * ''Isoplectron maculatum'' Hegg, Morgan-Richards & Trewick, 2024 * ''Isoplectron parallelum'' Hegg, Morgan-Richards & Trewick, 2024 * ''Isoplectron pallidum'' (Richards, 1972) * ''Isoplectron serratum'' (Richards, 1972) * ''Isoplectron virgatum'' Hegg, Morgan-Richards & Trewick, 2024

Predation

A study conducted by Bremner ''et al''. (1989) compared insect response to disturbance (touch) between individuals living with mammalian predators and those on mammal-free islands. Wētā were observed to jump away or leap off tree branches when disturbed in environments with rodents, but were more likely to move away without haste in environments without rodents. The paper concluded that invertebrate populations, specifically the ''Isoplectron'' sp. population in

Fiordland Fiordland (, "The Pit of Tattooing", and also translated as "the Shadowlands"), is a non-administrative geographical region of New Zealand in the south-western corner of the South Island, comprising the western third of Southland. Most of F ...

, altered their behaviour in environments that contained predators such as stoats (''Mustela erminea'') and ship rats (''Rattus rattus'') in comparison to predator free environments. Individuals within the genus ''Isoplectron'' are eaten by endemic reptiles such as the

Tuatara The tuatara (''Sphenodon punctatus'') is a species of reptile endemic to New Zealand. Despite its close resemblance to lizards, it is actually the only extant member of a distinct lineage, the previously highly diverse order Rhynchocephal ...

(''Sphenodon punctatus''), spotted skink (''

Oligosoma kokowai ''Oligosoma kokowai'', the northern spotted skink, is a species of skink found in New Zealand. References

Oligosoma Reptiles described in 2017 Endemic fauna of New Zealand Taxa named by Sabine Melzer Taxa named by Trent Bell Taxa named ...

'') and Pacific geckos (''

Dactylocnemis pacificus ''Dactylocnemis pacificus'', the Pacific gecko or Pacific sticky-toed gecko, is a species in the family (biology), family Gekkonidae, Endemism, endemic to the North Island and offshore islands of New Zealand. ''D. pacificus'' is the only describ ...

'') as well as avian species such as Rifleman ('' Acanthissitta chloris''), Ruru ('' Ninox novaeseelandiae''), Kākā ('' Nestor meridionalis'') and Tīeke ('' Philesturnus'').

Conservation

All species within the genus ''Isoplectron'' are considered not threatened and are consequently of little conservation concern.

References

Peripatus

{{DEFAULTSORT:Isoplectron Ensifera genera Cave wētā Endemic insects of New Zealand