Sigaus minutus

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Sigaus minutus
Sigaus minutus 3109728 (cropped).jpg
Status NZTCS D.svg
Declining (NZ TCS) [1]
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Orthoptera
Suborder: Caelifera
Family: Acrididae
Genus: Sigaus
Species:
S. minutus
Binomial name
Sigaus minutus
Bigelow, 1967

Sigaus minutus is a species of short-horned grasshopper in the family Acrididae. [2] It is one of the smallest and rarest species of grasshopper in New Zealand, found only in the Mackenzie district of South Island. There are nine species within the genus Sigaus [3] described by Bigelow (1967), [4] [5] all endemic to New Zealand. The population status of Sigaus minutus is declining according to threat assessments made by orthopteran experts in 2010. [6]

Contents

Habitat and distribution

Sigaus minutus is found near Lake Tekapo, Lindis Pass and in the Mackenzie district, South Island, New Zealand. [2] It has also been observed near Alexandra in Otago. [7] This grasshopper is very well camouflaged on stony surfaces and amongst lichen. [8] It is absent in areas of dense vegetation as it needs to bask. [8]

Morphological characters

Sigaus minutus is one of the smallest Sigaus species [4] but very similar to the Otago species S. childi. [2] Genetically, S. minutus is sister to the alpine species S. campestris from central and southern South Island mountains. [9] As seen in most New Zealand grasshoppers, these species are all without functioning wings and their cryptic colouring is variable within populations but always aids camouflage. Females are larger than males.

Dimensions

Adult male: length 9–10 mm, pronotum length 1.6-1.9 mm, pronotum width 1.80-2.20 mm, femur length 4.90-5.60 mm, femur width 1.60-1.90 mm. [2]

Adult female: length 14 –16 mm, pronotum length 2.50-2.65 mm, pronotum width 3.05- 3.30 mm, femur length 7.00-7.20 mm, femur width 2.10-2.50 mm. [2]

External characters

FEMALE

The fastigium is concave with upraised margins and bumps laterally on posterior margin. Posterior margin of pronotum sinuate with broad indent medially, sometimes with small v within the broad indentation (Bigelow, 1967). [4] [2] The character differentiating S. minutus from S. childi is the absence of a second pronotum suculus. [2]

MALE

Genitalia: principal lobes of lophi tongue-shaped, Mesal lobes very round projecting medially. Ancorae present, with bulbous swelling when viewed dorso-caudally narrowing to an inwardly directed point. Dorsal sclerite well developed as in other members of this genus, with broad lateral arms converging to form a broad, blunt, upturned projection with swelling at apex projecting caudal. Large swollen shell-shaped supraramus closely flanking the aedeagus. Dorsal aedeagal sclerites large and swollen, ventral aedeagal sclerites long. [2]

Behavior

As with other New Zealand grasshoppers, S. minutus is a diurnal herbivore, requiring open ground to bask. [4] Males are smaller than females when adult and will remain on the back on the females (in copula) during prolonged mating. Eggs are laid in the soil.

Areas for conservation

The majority of populations of S. minutus are on small isolated patches of privately owned farmland where land management practices will ensure their extinction. In a survey of 20 sites on Crawford Hills Rd, Alexandra (Jamieson & Manly 1997), no Sigaus childi or S. minutus were found on land which is in pasture, used for growing orchards, or being irrigated. Experiments have shown that acridids cannot tolerate insecticides or herbicides and are very sensitive to heavy metals and fertilizers in the soil. [10] [8]

Related Research Articles

<i>Hemiandrus</i> Genus of orthopteran insects

Hemiandrus is a genus of wētā in the family Anostostomatidae. In New Zealand they are known as ground wētā due to their burrowing lifestyle. Hemiandrus wētā are nocturnal, and reside in these burrows during the day. Ground wētā seal the entrance of their burrow during the day with a soil plug or door so that their burrow is concealed. This genus was originally said to be distributed in Australia and New Zealand, however, with recent molecular genetic methods, this is under debate. Ground wētā adults are smaller than other types of wētā, with the unusual trait of having both long and short ovipositors, depending on the species. The name of this genus is said to come from this trait as hemi- mean half and -andrus means male, as the species where the female has a short ovipositor can sometimes be mistaken for a male. This genus has a diverse diet, depending on the species.

<i>Sigaus homerensis</i> Species of grasshopper

Sigaus homerensis is a grasshopper endemic to the southern South Island of New Zealand. It is known only from three isolated populations in Fiordland.

<i>Sigaus childi</i> Species of grasshopper endemic to New Zealand and classified as critically endangered

Sigaus childi is an endangered protected species of grasshopper known only from the Alexandra district of the South Island of New Zealand. It is one of just two species of grasshopper listed for protection under the New Zealand Wildlife Act 1953. It is currently classified as "At Risk, Naturally Uncommon" by the Department of Conservation. The genus Sigaus is endemic to New Zealand.

<i>Brachaspis robustus</i> Species of grasshopper

Brachaspis robustus is a nationally endangered species of grasshopper endemic to the Mackenzie Basin of the South Island of New Zealand. The genus Brachaspis is endemic to the South Island of New Zealand. Although a grasshopper, it is a poor jumper, relying on camouflage to hide from predators. It is threatened by introduced mammals such as stoats, hedgehogs, and rats.

<i>Sigaus villosus</i> Species of grasshopper

Sigaus villosus is New Zealand's largest grasshopper. It is only found in the central mountains of the South Island. The genus Sigaus is endemic to the New Zealand. Like all of New Zealand sub-alpine and alpine grasshoppers S. villosus has a 2 or 3 years life cycle. The eggs must ‘overwinter’ before they will hatch. Hoppers are found throughout the year and adult grasshoppers can be found throughout the New Zealand summer between December and April. Adult S. villosus do not overwinter.

<i>Alpinacris tumidicauda</i> Species of grasshopper

Alpinacris tumidicauda is a species of grasshopper only known from Otago and Southland, New Zealand. The genus Alpinacris is endemic to the South Island of New Zealand. A. tumidicauda was described in 1967 by Robert Sidney Bigelow, with a type locality of Obelisk in the Old Man Range (45°19′22″S169°12′27″E). A male holotype and paratype are deposited in the Canterbury Museum, Christchurch. Like all of New Zealand sub-alpine and alpine grasshoppers, A. tumidicauda has a 2- or 3-year life cycle. The eggs must "overwinter" before they will hatch. Hoppers are found throughout the year, and adult grasshoppers can be found throughout the New Zealand summer between December and April. The adult A. tumidicauda do not overwinter.

<i>Sigaus</i> Genus of grasshoppers

Sigaus of grasshoppers in the tribe Catantopini that isendemic to New Zealand, and all but one species is endemic to the South Island: Sigaus piliferus is the only North Island representative and is the type species. There are eight species in the genus; all are flightless, and many are coloured for camouflage against rocky ground. Sigaus minutus and S. childi are threatened with extinction.

<i>Sigaus australis</i> Species of grasshopper

Sigaus australis is the most common alpine grasshopper found in New Zealand. It can be found in the southern half of the South Island above the tree line. Sigaus australis was described in 1897 by Frederick Hutton. Like all of New Zealand sub-alpine and alpine grasshoppers S. australis has a 2 or 3 years life cycle. Individuals can survive the cold by freezing solid at any life stage, at any time of the year. Sigaus australis adults are relatively large grasshoppers. The genus Sigaus is endemic to New Zealand.

<i>Alpinacris crassicauda</i> Species of grasshopper

Alpinacris crassicauda is a species of grasshopper only known from West Coast Region and Tasman Region, New Zealand. The genus Alpinacris is endemic to the South Island of New Zealand. A. crassicauda was described in 1967 by Robert Sidney Bigelow, with a type locality of Lead Hills, Boulder Lake. A male holotype and paratype are deposited in the Canterbury Museum, Christchurch. Like all of New Zealand sub-alpine and alpine grasshoppers A. crassicauda has a 2 or 3 years life cycle. The eggs must ‘overwinter’ before they will hatch. Hoppers are found throughout the year and adult grasshoppers can be found throughout the New Zealand summer between December and April. The adult A. crassicauda do not overwinter.

<i>Phaulacridium marginale</i> Species of grasshopper

Phaulacridium marginale is a small species of short-horned grasshopper in the family Acrididae. It is endemic to New Zealand where it is found in low elevation open habitat throughout North Island, South Island, Stewart Island and on many smaller islands.

<i>Stenobothrus rubicundulus</i> Species of grasshopper

Stenobothrus rubicundulus, the wing-buzzing grasshopper, is a species of short-horned grasshoppers in the family Acrididae.

<i>Phaulacridium otagoense</i> Species of grasshopper

Phaulacridium otagoense is an endemic New Zealand grasshopper found at low elevation throughout the central South Island.

<i>Brachaspis nivalis</i> Species of insect

Brachaspis nivalis, is an alpine short-horned grasshopper, endemic to the South Island of New Zealand. Brachaspis nivalis is brachypterous and flightless, therefore they travel by hopping. They bask during the day so need open habitat.

<span class="mw-page-title-main">Wētā</span> Informal group of orthopteran insects

Wētā is the common name for a group of about 100 insect species in the families Anostostomatidae and Rhaphidophoridae endemic to New Zealand. They are giant flightless crickets, and some are among the heaviest insects in the world. Generally nocturnal, most small species are carnivores and scavengers while the larger species are herbivorous. Although some endemic birds likely prey on them, wētā are disproportionately preyed upon by introduced mammals, and some species are now critically endangered.

<i>Brachaspis</i> Genus of insects

Brachaspis is a genus of grasshoppers belonging to the family Acrididae.

<i>Hemiandrus focalis</i> Species of orthopteran insect

Hemiandrus focalis is a species of ground wētā endemic to New Zealand. This flightless Orthoptera lives in the mountains of the South Island, New Zealand. This species can be distinguished from other ground wētā by their three superior retrolateral spines on their mid tibia and females have relatively long ovipositors. This omnivorous ground wētā species is listed as "not threatened" by the New Zealand Department of Conservation.

<i>Paprides</i>

Paprides is a genus of short-horned grasshoppers in the family Acrididae. There are at least two described species in Paprides, found in New Zealand. Both species were moved to the genus Sigaus in 2023

<i>Brachaspis collinus</i> Species of grasshopper

The Green Rock-hopper grasshopper, Brachaspis collinus is an alpine species of short-horned grasshopper in the family Acrididae. It is found in New Zealand in the mountains of northern South Island, above the tree line and as high as 2000 m asl. In New Zealand alpine grasshoppers can freeze solid at any time of the year and are alive when they thaw out when temperatures rise.

<i>Hemiandrus furoviarius</i> Species of wētā

Hemiandrus furoviarius, commonly known as the Tekapo ground wētā, is a wētā of the family Anostostomatidae. They are a small, flightless, and nocturnal orthopteran endemic to the Mackenzie Basin of New Zealand's South Island.

<i>Hemiandrus brucei</i> Species of wētā

Hemiandrus brucei is a species of ground wētā in the family Anostostomatidae endemic to New Zealand. They are nocturnal and found in forests in the North Island and northern South Island.

References

  1. ↑ "Sigaus minutus". NZTCS. Retrieved 27 May 2022.
  2. 1 2 3 4 5 6 7 8 Jamieson, Colleen D. (1999). "A new species of Sigaus from Alexandra, New Zealand (Orthoptera: Acrididae)". New Zealand Journal of Zoology. 26 (1): 43–48. doi: 10.1080/03014223.1999.9518176 . ISSN   0301-4223.
  3. ↑ "genus Sigaus Hutton, 1898: Orthoptera Species File". orthoptera.speciesfile.org. Retrieved 21 January 2022.
  4. 1 2 3 4 Bigelow, R. S. (1967). The Grasshoppers of New Zealand: their Taxonomy and Distribution. Pegasus Press, University of Canterbury.
  5. ↑ Jamieson, C. D. (Colleen Dusk) (1996). The grasshopper Sigaus minutus in Central Otago : a pilot study. New Zealand. Department of Conservation. Wellington, N.Z.: Dept. of Conservation. ISBN   0-478-01842-8. OCLC   53018797.
  6. ↑ Trewick, S. A.; Morris, S. J.; Johns, P. M.; Hitchmough, R. A.; Stringer, I. A.N. (2012). "The conservation status of New Zealand Orthoptera". New Zealand Entomologist. 35 (2): 131–136. doi:10.1080/00779962.2012.686318. ISSN   0077-9962. S2CID   219564547.
  7. ↑ "Galloway No. 1 Inland Saline Wetland Complex". www.orc.govt.nz. Retrieved 1 January 2024.
  8. 1 2 3 Jamieson, C. D. (Colleen Dusk) (1998). Distribution of the endangered grasshopper Sigaus minutus on the Earnscleugh tailings historic reserve. Dept. of Conservation. OCLC   154660958.
  9. ↑ Koot, Emily M.; Morgan-Richards, Mary; Trewick, Steven A. (1 June 2020). "An alpine grasshopper radiation older than the mountains, on Kā Tiritiri o te Moana (Southern Alps) of Aotearoa (New Zealand)". Molecular Phylogenetics and Evolution. 147: 106783. doi:10.1016/j.ympev.2020.106783. ISSN   1055-7903. PMID   32135305. S2CID   212567788.
  10. ↑ Heliövaara, K.; Väisänen, R. (1993). Insects and pollution. CRC Press. ISBN   1-351-08207-8. OCLC   1022776171.
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