Sigaus is a genus of grasshoppers in the tribe Catantopini that is endemic to New Zealand. All but one Sigaus species is endemic to the South Island: Sigaus piliferus is the only North Island representative[2] and is the type species. Most species in this genus are restricted to alpine habitats. All are wingless and make no sounds.
| Sigaus | |
|---|---|
| |
| Sigaus piliferus | |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Orthoptera |
| Suborder: | Caelifera |
| Family: | Acrididae |
| Tribe: | Catantopini |
| Genus: | Sigaus Hutton, 1897[1] |
| Species | |
|
Sigaus australis | |
There are thirteen species in the genus[3] all are adapted to cold conditions,[4] and many are coloured for camouflage against rocky ground.[5][6] The largest species Sigaus villosus can reach 48mm (body length of adult female).[5] The smallest species Sigaus minutus and S. childi are threatened with extinction.[7]
Taxonomy
editThe taxonomy of New Zealand endemic grasshoppers was substantially revised by Bigelow in 1967, based mostly on female genitalia,[5] and again in 2023 using genetic data.[3] The New Zealand radiation of cold-adapted grasshoppers is monophyletic but neither genetics nor morphology resolve distinctive genera, therefore it was suggested that all thirteen species be placed in the genus Sigaus.[3] The genus Sigaus is distinguished from other Acrididae as flightless, silent acridids with short tegmina, crypsis colouration and endemic to New Zealand. Each species has distinctive pronotum shape and structures of the internal male genitalia: the epiphallus lophi are saddle-like in shape with the mesal protuberance of the lophus having a smooth, rounded outline.[8] The genus is monophyletic and sister to grasshoppers from Tasmania, Australia.[9]
| Sigaus australis | Sigaus campestris | Sigaus childi | Sigaus australis (homerensis) | Sigaus minutus | Sigaus piliferus | Sigaus australis (obelisci) | Sigaus australis (takahe) | Sigaus villosus | |
|---|---|---|---|---|---|---|---|---|---|
| Photograph |  |
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 |
 |
 |
 |
 |
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| Elevation[10] | 1,300–1,700 m (4,300–5,600 ft) |
400–1,500 m (1,300–4,900 ft) |
200–500 m (660–1,600 ft) |
900–1,000 m (3,000–3,300 ft) |
300–800 m (980–2,600 ft) |
1,600–1,800 m (5,200–5,900 ft) |
1,000–1,400 m (5,900–6,900 ft) |
1,800–2,100 m (–6,900 ft) | |
| Described[11] | 1897[1] Hutton |
1897 Hutton |
1999[12] Jamieson |
2003[13] Morris |
1967[14] Bigelow |
1897 Hutton |
1967 Bigelow |
2003 Morris |
1950[15] Salmon |
| Habitat[16] | Tussock grasslands | Dry rocky hillsides/ tussock grasslands |
Dry rocky hillsides | Tussock grasslands | Fluvial outwash | Tussock grasslands | Alpine lichen fields | Tussock grasslands | Scree |
| Polymorphism[17] | Highly cryptic | Highly cryptic | Highly cryptic | 2 | Highly cryptic | 2 | Highly cryptic | 1 | |
| Regions | Canterbury Otago |
Canterbury Otago Southland |
Otago | Southland | Canterbury | Waikato Gisborne Hawke's Bay Manawatū-Whanganui Wellington |
Otago | Southland | Canterbury |
| Size[18] | Medium | Medium/large | Medium | Medium | Very small | Large | Large | Medium | Large |
| Status[19] | Not threatened | Not threatened | Nationally Critical | Range Restricted | Nationally Endangered | Not threatened | Range Restricted | Range Restricted | Not threatened |
| Wings[20] | Micropterous 2–3 mm |
Micropterous 2–3 mm |
Micropterous 1–2 mm |
Micropterous 2–3 mm |
Micropterous 1 mm |
Micropterous 3–4 mm |
Micropterous 3–4 mm |
Micropterous 2–4 mm |
References
edit- ^ a b Hutton, F.W. 1897: "The grasshoppers and locusts of New Zealand and the Kermadec Islands". Transactions of the New Zealand Institute 30: 135-50
- ^ Meza-Joya, Fabio Leonardo; Morgan-Richards, Mary; Trewick, Steven A. (2024). "Phenotypic and genetic divergence in a cold-adapted grasshopper may lead to lineage-specific responses to rapid climate change". Diversity and Distributions. 30 (6). doi:10.1111/ddi.13848. ISSN 1366-9516.
- ^ a b c Trewick, Steven A.; Koot, Emily M.; Morgan-Richards, Mary (2023). "Māwhitiwhiti Aotearoa: Phylogeny and synonymy of the silent alpine grasshopper radiation of New Zealand (Orthoptera: Acrididae)". Zootaxa. 5383 (2): 225–241. doi:10.11646/zootaxa.5383.2.7. ISSN 1175-5334.
- ^ Koot, Emily M.; Morgan-Richards, Mary; Trewick, Steven A. (2022). "Climate change and alpine-adapted insects: modelling environmental envelopes of a grasshopper radiation". Royal Society Open Science. 9 (3). Bibcode:2022RSOS....911596K. doi:10.1098/rsos.211596. ISSN 2054-5703. PMC 8889178. PMID 35316945.
- ^ a b c Bigelow, R.S. 1967. The Grasshoppers of New Zealand, Their Taxonomy and Distribution. University of Canterbury, Christchurch. p. 60.
- ^ 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.
- ^ 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. Bibcode:2012NZEnt..35..131T. doi:10.1080/00779962.2012.686318. ISSN 0077-9962. S2CID 219564547.
- ^ Morris, S.J. 2002: Identification guide to grasshoppers (Orthoptera: Acrididae) in Central Otago and Mackenzie Country. DOC Science Internal Series 26. Department of Conservation, Wellington. 17 p.
- ^ Koot, Emily M.; Morgan-Richards, Mary; Trewick, Steven A. (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. Bibcode:2020MolPE.14706783K. doi:10.1016/j.ympev.2020.106783. ISSN 1055-7903. PMID 32135305. S2CID 212567788.
- ^ Species prefer altitude.
- ^ The author and year the species was described.
- ^ A new species of Sigaus from Alexandra, New Zealand (Orthoptera: Acrididae). New Zealand Journal of Zoology, 26: 43-48.
- ^ Morris, S.J. 2003: "Two new species of Sigaus from Fiordland, New Zealand (Orthoptera: Acrididae)". New Zealand entomologist, 26: 65–74. PDF Archived 2011-07-21 at the Wayback Machine
- ^ Bigelow, R.S. 1967: The Grasshoppers of New Zealand, Their Taxonomy and Distribution. University of Canterbury, Christchurch.
- ^ Salmon, J.T. 1950: A new species of Acrididae (Insecta: Orthoptera) from New Zealand. Transactions of the Royal Society of New Zealand, Vol. 78, Part 1, page 69, February 1950
- ^ Species prefer habitat.
- ^ The number of colour morphs known for adults of this species.
- ^ Size for adult males: Small less than 6 mm; Medium 6-30 mm & Large greater than 30 mm.
- ^ Base on the New Zealand Threat Classification System
- ^ Species wing length.
External links
edit
- Sigaus discussed on RNZ Critter of the Week, 3 March 2017
- Citizen science observations in iNaturalist