''Clitarchus hookeri'', is a

stick insect The Phasmatodea (also known as Phasmida, Phasmatoptera or Spectra) are an order of insects whose members are variously known as stick insects, stick-bugs, walking sticks, stick animals, or bug sticks. They are also occasionally referred to as ...

of the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Phasmatidae The Phasmatidae are a family of the stick insects ( order Phasmatodea). They belong to the superfamily Anareolatae of suborder Verophasmatodea. Like many of their relatives, the Phasmatidae are capable of regenerating limbs and commonly repr ...

endemic Endemism is the state of a species being found 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 found elsew ...

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

. It is possibly New Zealand's most common stick insect. ''Clitarchus hookeri'' is often green in appearance, but can also be brown or red. Alongside the prickly stick insect and the Unarmed stick insect, ''C. hookeri'' is one of three stick insect species to have become naturalised in

Great Britain Great Britain is an island in the North Atlantic Ocean off the northwest coast of continental Europe. With an area of , it is the largest of the British Isles, the largest European island and the ninth-largest island in the world. It is ...

, with all three having originated in New Zealand.

Description

''Clitarchus hookeri'' is a large stick insect. This species demonstrates

sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...

. Female specimens grow from 81 – 106 mm and males from 67 – 74 mm. The colour can be variable, even in the same location, ranging from bright green to grey, brown or buff. Unlike many tropical stick insects, ''Clitarchus hookeri'' is flightless.

Habitat and distribution

''Clitarchus hookeri'' is found from Northland to the

Wellington Wellington ( mi, Te Whanganui-a-Tara or ) is the capital city of New Zealand. It is located at the south-western tip of the North Island, between Cook Strait and the Remutaka Range. Wellington is the second-largest city in New Zealand by me ...

region in the south of the

North Island The North Island, also officially named Te Ika-a-Māui, is one of the two main islands of New Zealand, separated from the larger but much less populous South Island by the Cook Strait. The island's area is , making it the world's 14th-largest ...

of New Zealand. On the

South Island The South Island, also officially named , is the larger of the two major islands of New Zealand in surface area, the other being the smaller but more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman ...

it is not as widespread, being found mainly in eastern coastal areas from

Nelson Nelson may refer to: Arts and entertainment * ''Nelson'' (1918 film), a historical film directed by Maurice Elvey * ''Nelson'' (1926 film), a historical film directed by Walter Summers * ''Nelson'' (opera), an opera by Lennox Berkeley to a lib ...

and

Marlborough Marlborough may refer to: Places United Kingdom * Marlborough, Wiltshire, England ** Marlborough College, public school * Marlborough School, Woodstock in Oxfordshire, England * The Marlborough Science Academy in Hertfordshire, England Austral ...

in the north through

Canterbury Canterbury (, ) is a City status in the United Kingdom, cathedral city and UNESCO World Heritage Site, situated in the heart of the City of Canterbury local government district of Kent, England. It lies on the River Stour, Kent, River Stour. ...

to its southern limit in

Dunedin Dunedin ( ; mi, Ōtepoti) is the second-largest city in the South Island of New Zealand (after Christchurch), and the principal city of the Otago region. Its name comes from , the Scottish Gaelic name for Edinburgh, the capital of Scotland. Th ...

. It is also found in Great Britain, where it has been introduced. The UK population is all-female but came from a sexual population in

Taranaki Taranaki is a region in the west of New Zealand's North Island. It is named after its main geographical feature, the stratovolcano of Mount Taranaki, also known as Mount Egmont. The main centre is the city of New Plymouth. The New Plymouth Dist ...

. The species is most commonly found on manuka, but has also been observed feeding on kanuka,

pohutukawa ''Metrosideros excelsa'', commonly known as pōhutukawa ( mi, pōhutukawa), New Zealand Christmas tree, New Zealand Christmas bush, and iron tree, is a coastal evergreen tree in the myrtle family, Myrtaceae, that produces a brilliant display o ...

, ''

Muehlenbeckia australis ''Muehlenbeckia australis'', the large-leaved muehlenbeckia or pohuehue, is a prostrate or climbing plant native to New Zealand. Description The species grows up to tall with grey bark. The leaves are on stiff petioles and are long. Lamina is ...

'',

roses A rose is either a woody perennial flowering plant of the genus ''Rosa'' (), in the family Rosaceae (), or the flower it bears. There are over three hundred species and tens of thousands of cultivars. They form a group of plants that can be e ...

, white rata, and ''

Coprosma ''Coprosma'' is a genus of flowering plants in the family Rubiaceae. It is found in New Zealand, Hawaiian Islands, Borneo, Java, New Guinea, islands of the Pacific Ocean to Australia and the Juan Fernández Islands. Description The name ''Copros ...

''.

Life cycle & mating behaviour

''Clitarchus hookeri'' are

hemimetabolous Hemimetabolism or hemimetaboly, also called incomplete metamorphosis and paurometabolism,McGavin, George C. ''Essential Entomology: An Order-by-Order Introduction''. Oxford: Oxford University Press, 2001. pp. 20. is the mode of development of certa ...

, meaning that the

nymphs A nymph ( grc, νύμφη, nýmphē, el, script=Latn, nímfi, label=Modern Greek; , ) in ancient Greek folklore is a minor female nature deity. Different from Greek goddesses, nymphs are generally regarded as personifications of nature, are typ ...

grow through a series of six

instar An instar (, from the Latin '' īnstar'', "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (''ecdysis''), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or ass ...

s before a final moult into their adult stage. Adults are found during the summer months and are mostly active at night. During the day they hide among the branches of their host trees, before emerging at sunset to feed and mate. Females hang off the edge of branches feeding on the leaves of their host plant and signalling to males by releasing a mix of volatile chemicals. The long-legged adult males move around at night in search of mates. Males court females by laying his forelegs across her for between 10 minutes to 1 hour, after which he climbs onto the female and attempts to clasp onto her sub genital plate using his genital claspers. If the male successfully attaches to the female, mating begins when the female's operculum opens and the male inserts his genitalia. Males remain attached to the female for extended periods, ranging from one through to 10 nights, during which they may mate multiple times. Moulting Clitarchus hookeri

''Clitarchus hookeri'' is geographically

parthenogenetic Parthenogenesis (; from the Greek grc, παρθένος, translit=parthénos, lit=virgin, label=none + grc, γένεσις, translit=génesis, lit=creation, label=none) is a natural form of asexual reproduction in which growth and development ...

, meaning that in some localities females do not mate to reproduce. Instead, they are able to produce fertile eggs without mating. In the South Island ''Clitarchus hookeri'' males are rare or absent, while in the North Island both asexual and sexual populations occur. Although females who reproduce asexually lay similar number of eggs and have similar hatching success as those who

reproduce sexually Sexual reproduction is a type of reproduction that involves a complex life cycle in which a gamete ( haploid reproductive cells, such as a sperm or egg cell) with a single set of chromosomes combines with another gamete to produce a zygote tha ...

, their eggs took longer to hatch. Eggs from parthenogenic females took between 21 and 23 weeks, while eggs from mated females took between 9–16 weeks. Females from parthenogenetic populations show a barrier to fertilization in captivity when provided with mates, however, males cannot distinguish between sexual and parthenogenetic females. However, two wild populations in New Zealand have reverted to sexual reproduction very recently. PHAS Phasmidae Clitarchus hookeri egg1

Phylogeography

With the exception of the West Coast of the South Island, the current distribution of ''Clitarchus hookeri'' is widespread on both the North and South Islands of New Zealand. It is thought that its distribution restricted at the

Last Glacial Maximum The Last Glacial Maximum (LGM), also referred to as the Late Glacial Maximum, was the most recent time during the Last Glacial Period that ice sheets were at their greatest extent. Ice sheets covered much of Northern North America, Northern Eur ...

to refugia in the northern North Island and the east coast of the South Island. It is thought that parthenogenetic female members of the species were able to recolonize areas more favourably following the glacial retreat. South Island individuals and those from the southern region of the North Island form a single

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

with very low genetic diversity. Upper North Island individuals are much more diverse genetically. It is thought that the lack of genetic diversity in the lower North Island/South Island population to be due to its younger lineage than their sexually reproducing relatives.

References

External links