Sigaus

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 Sigaus campestris Sigaus crassicauda Sigaus collinus Sigaus childi Sigaus dugdali Sigaus minutus Sigaus nitidus Sigaus nivalis Sigaus piliferus Sigaus robustus Sigaus tumidicauda Sigaus villosus

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.

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

The 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
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

1. Hutton, F.W. 1897: "The grasshoppers and locusts of New Zealand and the Kermadec Islands". Transactions of the New Zealand Institute 30: 135-50
2. 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.
3. 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.
4. 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.
5. Bigelow, R.S. 1967. The Grasshoppers of New Zealand, Their Taxonomy and Distribution. University of Canterbury, Christchurch. p. 60.
6. 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.
7. 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.
8. 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.
9. 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.
10. Species prefer altitude.
11. The author and year the species was described.
12. A new species of Sigaus from Alexandra, New Zealand (Orthoptera: Acrididae). New Zealand Journal of Zoology, 26: 43-48.
13. 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
14. Bigelow, R.S. 1967: The Grasshoppers of New Zealand, Their Taxonomy and Distribution. University of Canterbury, Christchurch.
15. 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
16. Species prefer habitat.
17. The number of colour morphs known for adults of this species.
18. Size for adult males: Small less than 6 mm; Medium 6-30 mm & Large greater than 30 mm.
19. Base on the New Zealand Threat Classification System
20. Species wing length.

External links

• Sigaus discussed on RNZ Critter of the Week, 3 March 2017
• Citizen science observations in iNaturalist