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''Sigaus nivalis'', is an alpine short-horned grasshopper,
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 the
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 ...
of New Zealand. ''Sigaus nivalis'' is
brachypterous Brachyptery is an anatomical condition in which an animal has very reduced wings. Such animals or their wings may be described as "brachypterous". Another descriptor for very small wings is microptery. Brachypterous wings generally are not functi ...
and flightless, therefore they travel by hopping. They bask during the day so need open habitat.


Taxonomy/history

'Sigaus' means silent and 'nivalis' means of the snow, so the name translates as the Quiet snow grasshopper. The species was first reported and described by Captain Frederick Wollaston Hutton from the
Mount Cook Aoraki / Mount Cook is the highest mountain in New Zealand. Its height, , is listed as . It is situated in the Southern Alps, the mountain range that runs the length of the South Island. A popular tourist destination, it is also a favourite ch ...
area and
Marlborough Marlborough or the Marlborough may refer to: Places Australia * Marlborough, Queensland * Principality of Marlborough, a short-lived micronation in 1993 * Marlborough Highway, Tasmania; Malborough was an historic name for the place at the sou ...
in 1897, but was put in the genus '' Pezotettix'' with some synonyms at that time.Hutton, F.W. (1897).
The Grasshoppers and Locusts of New Zealand and the Kermadec Islands
. ''Proceedings and Transactions of the New Zealand Institute'' 30: 135–150.
In 1898, Hutton proposed a new genus ''"Brachaspis"'' (from its short and broad sternal shield) and put in ''B. nivalis''.Hutton, F.W. (1898).

''Proceedings and Transactions of the New Zealand Institute'' 31: 44–50.
In 1967, Bigelow revised ''Brachaspis'' and redefined three species. This group is
monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...
, nested within the New Zealand alpine grasshopper clade. In 2023 morphological and genetic data was used to group all 13 New Zealand endemic alpine grasshoppers into a single genus (''Sigaus''). ''Sigaus nivalis'' includes populations from Canterbury and Kaikoura and is morphologically distinguished from the other species (''Sigaus collinus'' & ''Sigaus
robustus Robustus, robust in Latin, may refer to: * '' Atheris squamiger robustus'', a subspecies in the species ''Atheris squamigera'', the green bush viper, variable bush viper or leaf viper, a viper species found in west and central Africa * '' Cebus ni ...
''). Although hybridization between ''S. nivalis'' and ''S. collinus'' is suggested by
ITS ITS, its or it's may refer to: Language * It's, an English contraction of ''it is'' or ''it has'' * Its (pronoun), the possessive form of the pronoun it * Itsekiri language (ISO 639 language code its), a language found in Nigeria and the Niger De ...
DNA sequence data in
Mount Lyford Mount Lyford (1590m) is the home of an alpine village and ski resort in the South Island of New Zealand. It is 146 kilometres by road north of Christchurch on the Inland Kaikōura Road (SH70) between Culverden and Kaikōura. The resort is a 40- ...
where these species are sympatric, they are still considered different phylogenetic species on the basis of morphology, mtDNA ( COI) sequence and geographical distribution. Furthermore, the genetic sequence data (COI & ITS) suggests that ''B. nivalis'' comprises northern and southern subgroups, that meet at the Rangitata River in
Canterbury Canterbury (, ) is a City status in the United Kingdom, city and UNESCO World Heritage Site, in the county of Kent, England; it was a county borough until 1974. It lies on the River Stour, Kent, River Stour. The city has a mild oceanic climat ...
. Both mtDNA and nuclear markers of southern ''S. nivalis'' and ''S. robustus'' are very similar with evidence of hybridization between these two species.


Type information

*''Pezotettix'' ''nivalis''; unspecified primary type of species ''Brachaspis'' ''nivalis'' (Hutton, 1898). Hutton, F.W. (1897). The Grasshoppers and Locusts of New Zealand and the Kermadec Islands. ''Proceedings and Transactions of the New Zealand Institute'' 30: 135–150. *Locality: New Zealand, New Zealand South I: Canterbury, Mt. Cook region; . *Type specimen: Female; G. E. Mannering; the type is deposited in the Canterbury Museum, Christchurch.


Habitat and distribution

''Sigaus nivalis'' is common in rocky montane areas with scattered plants (unlike ''S. collinus'' which are mostly found in tussock grass in the
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 ...
region). The elevational range of ''S. nivalis'' is between 600 and 2000 metres above mean sea level. The distribution of ''S. nivalis'' is widespread at high elevation in South Island New Zealand from Marlborough,
Canterbury Canterbury (, ) is a City status in the United Kingdom, city and UNESCO World Heritage Site, in the county of Kent, England; it was a county borough until 1974. It lies on the River Stour, Kent, River Stour. The city has a mild oceanic climat ...
and north
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 ...
.


Morphology

''Sigaus nivalis'' is polymorphic and has
cryptic coloration Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the b ...
resembling the surrounding rocky habitat. The color morphs can be either grey or grey mottled brown. Individuals with scarlet, purple or indigo-black flash-display of the hind legs have been collected at various sites (unlike the reddish brown hind legs in ''S. collinus''). Males are usually smaller than females. The known body length of males range between 15–24 mm, and the females between 16–40 mm. The length of the hind femur of males are 8.5-12.5 mm, and the females are 11.5–17 mm. Generally, the body size of ''S. nivalis'' is smaller than ''S. robustus.'' Body size of adult ''S. nivalis'' increases with elevation, the largest individuals are found above 1200m asl and the smallest on stream edges at low elevation.


Diet

''Sigaus nivalis'' shows multiple and opportunistic feeding behavior. It is a herbivore and prefers to eat the floral parts of plants. It was observed to feed on plants such as '' Hebe spp.'', ''
Epilobium ''Epilobium'' is a genus of flowering plants in the family Onagraceae, containing about 197 species. The genus has a worldwide distribution. It is most prevalent in the subarctic, temperate and subantarctic regions, whereas in the subtropics and ...
'' ''spp.'', ''
Celmisia ''Celmisia'' (New Zealand aster or New Zealand daisy) is a genus of perennial herbs or subshrubs, in the family Asteraceae. Most of the species are endemic to New Zealand; several others are endemic to Australia. ; Species and nothospecies #RED ...
spp.,
Poa ''Poa'' is a genus of about 570 species of Poaceae, grasses, native to the temperate regions of both hemispheres. Common names include meadow-grass (mainly in Europe and Asia), bluegrass (mainly in North America), tussock (some New Zealand spe ...
spp., Wahlenbergia albomarginata, Anisotome aromatica, Chionochloa pallens, Coprosma pumila, Pittosporum crassicaule,'' ferns such as ''
Austroblechnum penna-marina ''Austroblechnum penna-marina'', synonym ''Blechnum penna-marina'', known as Antarctic hard-fern, Little Hard Fern, Alpine Hard Fern, alpine water fern and pinque (Chilean Spanish), is a species of fern in the family Blechnaceae. It is a widely ...
,'' mosses such as ''
Polytrichum juniperinum ''Polytrichum juniperinum'', commonly known as juniper haircap or juniper polytrichum moss, is an evergreen and perennial species of moss that is widely distributed, growing on every continent including Antarctica. Description The stems are redd ...
'' and unidentified lichens''.'' In addition, ingestion of arthropods was found in adult ''B. nivalis,'' but it may be upon opportune contact.


Life history

Males undergo six instars and females undergo seven instars to become adults. First and second instars are suggested to be abundant during January and February. The mating activity of ''B. nivalis'' extends throughout the life span of adults. The maximum longevity of male adults are 21.8 months, and the for females are 26.1 months.


Reproduction

''Sigaus nivalis'' shows multiple mating with a different non-bonded mate on each occasion. When a male tries to mate, it often aggressively mounts a resisting female. The male firmly grabs the female to prevent detachment by sudden disturbance. Mating pairs have been observed from spring to autumn (September - April). Gravid females were also observed from September to May except April, and number were highest in January and February. Females show multiple oviposition. Each egg pod may contain 20-30 eggs and first instars are observed in late December or early January.


Conservation

''Sigaus nivalis'' was assessed to be not threatened (NT) level of NZTCS in 2022. This status has not changed from prior assessments in 2014 and 2010. However, if further population genetic research suggests that the small, low-elevation forms are distinct from their montane relatives, the conservation status of the low-elevation forms has to be considered threatened by flooding events, land development, weed invasion and introduced predators. The population abundance of ''S. nivalis'' correlates with soil temperature. Therefore, the increase in mean temperature due to global warming may cause ''S. nivalis'' to lose suitable habitat in the future.


References

{{Taxonbar, from=Q10434090 Catantopinae Acrididae of New Zealand Endemic insects of New Zealand