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Classification and identification

Following Günther (1953), the New Zealand stick insects are placed into the subfamilies Phasmatinae and Pachymorphinae.

Phasmatodea: Phasmatidae: Phasmatinae: Acanthoxylini

Phasmatodea: Phasmatidae: Pachymorphinae: Pachymorphinini

Our studies (Buckley et al. 2009; 2010b) have shown this classification to be inconsistent with the phylogeny of the genera. All of the New Zealand genera, with the exception of Spinotectarchus form a monophyletic group and are related to species from New Caledonia (Buckley et al. 2010b). Stick insects can be identified by the arrangement of body spines, body size, structure of the male and female terminalia and the morphology of the egg.

Phasmatodea: Phasmatidae: Phasmatinae: Acanthoxylini

Acanthoxyla Uvarov

The genus Acanthoxyla is very unusual in that it contains only females and reproduces via asexual reproduction or parthenogenesis. Most of these species are common, and they thrive on garden plants such as roses and ornamental conifers. In native forest and scrub throughout the North Island and large areas of the South  Island these species can be found on trees such as rimu, totara and on climbing rata.

There are 8 currently recognised species in the genus:

  • Acanthoxyla prasina (Westwood 1859)
  • Acanthoxyla geisovii (Kaup 1866)
  • Acanthoxyla fasciata (Hutton 1899)
  • Acanthoxyla suteri (Hutton 1899)
  • Acanthoxyla intermedia Salmon 1955
  • Acanthoxyla inermis Salmon 1955
  • Acanthoxyla speciosa Salmon 1955
  • Acanthoxyla huttoni Salmon 1955

They are large insects from 8 to 11 cm long and are usually green or brown. Most species have black tipped spines although these are absent in A. inermis and highly reduced in some other Acanthoxyla species. Currently available species descriptions do not allow reliable identification of many of the different species and should be used with caution. Genetic studies show that Acanthoxyla species have most likely arisen via hybridization (Morgan-Richards and Trewick 2005; Buckley et al. 2008).

Argosarchus Hutton

his genus contains our largest stick insects and at up to 15 cm have the longest body-length of any New Zealand insect. They are found throughout much of the North Island and large areas of the South  Island. They are commonly found in gardens on ramarama and in the wild on horahora, native and introduced Rubus sp. and climbing ratas. As with most New Zealand stick insects some populations consist of females only (Buckley et al. 2009).

  • Argosarchus horridus (White 1846)
  • Argosarchus spiniger (White 1846)

The descriptions and keys of Salmon (1991) do not allow unambiguous differentiation of Argosarchus horridus from Argosarchus spiniger (White 1846). Furthermore, the type specimen of Argosarchus spiniger is most likely a male of Argosarchus horridus making the former species a synonym of the later. The two species described by Salmon are not able to be differentiated using genetic data (Trewick et al. 2005; Buckley et al. 2009). Phylogeographic study (Buckley et al. 2009) shows evidence of post-glacial population expansion from northern refugia following climatic warming.

Clitarchus Stål

This genus is perhaps the most common stick insect in New Zealand. It is very common on kanuka and manuka throughout the North Island and part of the South  Island. These species are usually green, but can often be various shades of brown or even red. Some individuals have many tubercles on the body surface. There are three recognized species in the genus:

  • Clitarchus hookeri (White 1846)
  • Clitarchus rakauwhakanekeneke Buckley, Myers, and Bradler 2014
  • Clitarchus tepaki Buckley, Myers, and Bradler 2014

Clitarchus tepaki is found only in the Cape Reinga and Karikari Peninsulas, northern New Zealand. Clitarchus rakauwhakanekeneke is restricted to the Poor Knights Islands. Some populations of C. hookeri species contain only females and so must reproduce via parthenogenesis (Buckley et al. 2008, 2010a; Morgan-Richards et al. 2010).

Pseudoclitarchus Salmon

Pseudoclitarchus sentus (Salmon 1948)

This species is found mainly on kanuka on the Three Kings Islands. It has been recorded from both Great Island and South West Island. It is most common on kanuka.

Tepakiphasma Buckley and Bradler

Tepakiphasma ngatikuri Buckley & Bradler 2010

This species has been collected from climbing rata (Metrosideros perforata). The female is relatively large being over 10 cm long. Due to the extremely restricted geographic range of this genus it is of high conservation concern.

Phasmatodea: Phasmatidae: Pachymorphinae: Pachymorphinini

Asteliaphasma Jewell and Brock

This genus is found throughout the upper half of the North Island, including some offshore island, in native forest. It is most easily found on climbing rata. There are two described species:

  • Asteliaphasma naomi (Salmon 1991)
  • Asteliaphasma jucundum (Salmon 1991)

Individuals of Asteliaphasma can be up to 9 cm long and tend to be very gracile with thin legs. Some individuals have prominent lobes on the legs and abdomen. Like the genus Spinotectarchus, the eggs of Asteliaphasma are covered in spines. For this reason these species used to be included in the same genus, however their terminalia are quite different and so were separated by Jewell and Brock (2002). The current species descriptions do not allow reliable identification of the two Asteliaphasma species and the exact number of valid species is not apparent. Because these stick insects are very poorly represented in collection we are undertaking a survey of upper North Island forests to determine the range of genetic and morphological variation. These data will be used to determine exactly how many species of Asteliaphasma there are.

Micrarchus Carl

This genus contains one described species that is found throughout the southern half of the North Island and the northern South Island. This species can be found on kanuka and other shrubs. The currently recognised species is:

Micrarchus hystricuelus (Westwood 1859)

This genus contains a number of undescribed species from the northern South Island that are currently being researched (Dunning et al. 2014). At least one of these species is restricted to habitat above the tree line. Species of Micrarchus are small, always brown in colour and often with numerous spines. Their eggs are also highly distinctive.

Niveaphasma Jewell and Brock

The genus Niveaphasma is unusual among stick insects in that it can occur in alpine areas (Dennis et al. 2014). The genus currently contains only one recognized species.

Niveaphasma annulata (Hutton 1898)

This species is more common in the southern half of the South Island and has not been collected north of Arthurs Pass. The genus appears to be absent from the North Island. Most specimens are grey or brown in colour with distinct flanges and lobes on the body and legs. Some populations from inland alpine areas lack males and are parthenogenetic. Our genetic work shows different populations were restricted to a number of refugia in the lower South Island during recent glacial advances (O’Neil et al. 2009).

Spinotectarchus Salmon

This genus contains only one species that is restricted to the northern North Island and some offshore islands. It is commonly found on rata and some other plants in native forest. Both males and females are known. The single recognized species is:

Spinotectarchus acornutus (Hutton 1899)

The eggs of this species are covered in short spines giving it a hairy appearance. This character is also shared with the genus Asteliaphasma although the genitalia of both genera are quite different. Phylogenetic studies show it is unrelated to the other New Zealand stick insect genera (Buckley et al. 2010b).

Tectarchus Salmon

Species from the genus Tectarchus are common throughout much of the North Island and northern South Island. These species can be found on Astelia epiphytes, rata, and Coprosma. There are four recognised species:

  • Tectarchus salebrosus (Hutton 1899)
  • Tectarchus huttoni (Brunner 1907)
  • Tectarchus ovobessus Salmon 1954
  • Tectarchus semilobatus Salmon 1954

Tectarchus huttoni and Tectarchus ovobessus are usually green coloured although light brown forms are common also. Tectarchus salebrosus and Tectarchus semilobatus are usually light or dark brown in colour. One of the best ways to identify these species is by the shape of their eggs. Although Salmon (1991) stated that T. ovobessus was parthenogenetic we have found numerous sexual populations.