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Gasteracantha

{{Short description|Genus of spiders}}

{{Automatic taxobox

| image = Spiny-backed orb-weaver (Gasteracantha sanguinolenta) female dorsal Principe.jpg

| image_caption = G. sanguinolenta dorsal side

| taxon = Gasteracantha

| authority = Sundevall, 1833

| type_species = G. cancriformis

| type_species_authority = (Linnaeus, 1758)

| subdivision_ranks = Species

| synonyms =

  • Bunocrania Thorell, 1878
  • Paurotylus Tullgren, 1910

| synonyms_ref =

}}

Gasteracantha is a genus of orb-weaver spiders first named by Carl Jakob Sundevall in 1833.{{cite book |last=Sundevall |first=C. J. |year=1833 |title=Conspectus Arachnidum |location=Lund, Sweden |page=14 }} Species of the genus are known as spiny-backed orb-weavers, spiny orb-weavers, or spiny spiders. The females of most species are brightly colored with six prominent spines on their broad, hardened, shell-like abdomens. The name Gasteracantha is derived from the Greek {{Transliteration|grc|gaster}} ({{lang|grc|γαστήρ}}), meaning "belly, abdomen", and {{Transliteration|grc|akantha}} ({{lang|grc|άκανθα}}), meaning "thorn, spine".{{cite web |title=Genus Gasteracantha |publisher=BugGuide |accessdate=2019-05-13 |url=https://bugguide.net/node/view/1982}} Spiny-backed orb-weavers are sometimes colloquially called "crab spiders" because of their shape, but they are not closely related to the true crab spiders.{{cite web |title=Species Gasteracantha cancriformis - Spinybacked Orbweaver |url=https://bugguide.net/node/view/2026 |website=BugGuide.net |accessdate=4 August 2019}} Other colloquial names for certain species include thorn spider,{{cite web |last1=Williams |first1=Steven |title=Spiky Spiders |url=https://morethanadodo.com/2016/06/13/spiky-spiders/ |website=More than a Dodo |publisher=Oxford Museum of Natural History |accessdate=4 August 2019}} star spider,{{cite book |last1=Horwell |first1=David |last2=Oxford |first2=Pete |title=Galápagos Wildlife |date=August 2005 |publisher=Bradt Travel Guides Ltd |location=Chalfont St Peter, Bucks SL9 9QE, England |isbn=9781841621005 |page=26 |edition=2}} kite spider, or jewel spider.

Members of the genus exhibit strong sexual dimorphism. Females are several times larger than males, which lack prominent spines or bright colors.{{cite journal |last1=Sankaran |first1=Pradeep M. |last2=Jobi |first2=Malamel J. |last3=Sebastian |first3=Pothalil A. |title=Redescription of the orb-weaving spider Gasteracantha geminata (Fabricius, 1798) (Araneae, Araneidae) |journal=Zootaxa |date=February 2015 |volume=3915 |issue=1 |pages=147–150 |doi=10.11646/zootaxa.3915.1.10 |url=https://biotaxa.org/Zootaxa/article/view/zootaxa.3915.1.10 |accessdate=4 August 2019|url-access=subscription }}

Other genera in the same family are also known as spiny orb-weavers.{{cite journal |last1=Scharff |first1=Nikolaj |last2=Coddington |first2=Jonathan A. |last3=Blackledge |first3=Todd A. |last4=Agnarsson |first4=Ingi |last5=Framenau |first5=Volker W. |last6=Szűts |first6=Tamás |last7=Hayashi |first7=Cheryl Y. |last8=Dimitrov |first8=Dimitar |title=Phylogeny of the orb‐weaving spider family Araneidae (Araneae: Araneoidea) |journal=Cladistics |date=23 April 2019 |volume=36 |pages=1–21 |doi=10.1111/cla.12382|hdl=1956/22200 |hdl-access=free }}

Distribution

Gasteracantha species are distributed worldwide in tropical and subtropical climates. The genus is most diverse in tropical Asia, from India through Indonesia.{{cite web|title=Gen. Gasteracantha Sundevall, 1833|url=https://wsc.nmbe.ch/genus/323/Gasteracantha|website=World Spider Catalog|publisher=Natural History Museum Bern|accessdate=18 November 2021}} One species, G. cancriformis, occurs in the Americas.

Predators and defense mechanisms

Some species of orb-weavers use stridulation as an antipredator defense mechanism.Corey, T. B., & Hebets, E. A. (2020). Testing the hypothesized antipredator defence function of stridulation in the spiny orb-weaving spider, Micrathena gracilis. Animal Behaviour, 169, 103–117. https://doi.org/10.1016/j.anbehav.2020.09.003 Orb-weavers' bites are generally harmless to humans.{{Cite web| url=https://entomology.ca.uky.edu/spider-chart#orb| title=Urban Spider Chart}}

Taxonomy and systematics

Gasteracantha has a complex taxonomic history, and many questions of species limits and distribution and generic interrelationships remain unanswered. Furthermore, challenges include the variability within individual Gasteracantha species (e.g., color polymorphism and variable length and shape of spines), a lack of male specimens and descriptions for many species, missing or damaged type specimens, and ambiguous initial descriptions in 18th- and 19th-century scientific literature.{{cite journal |last1=Tan |first1=Ji |last2=Chan |first2=Zi Yang |last3=Ong |first3=Ching Ang |last4=Yong |first4=Hoi Sen |title=Phylogenetic relationships of Actinacantha Simon, Gasteracantha Sundevall, Macracantha Hasselt and Thelacantha Simon spiny orb-weavers (Araneae: Araneidae) in Peninsular Malaysia |journal=Raffles Bulletin of Zoology |date=14 February 2019 |volume=67 |pages=32–55 |doi=10.26107/RBZ-2019-0003 |url=https://lkcnhm.nus.edu.sg/app/uploads/2018/11/RBZ-2019-0003.pdf |accessdate=3 August 2019}} The 69 species currently recognized by World Spider Catalog include dozens of synonyms and subspecies, many based on literature well over 100 years old.

A 2019 study examining three mitochondrial and two nuclear genes found that Gasteracantha is paraphyletic with respect to Macracantha, Actinacantha, and Thelacantha. M. arcuata is allied with G. hasselti and A. globulata, while T. brevispina is closer to G. kuhli and G. diardi. The authors, however, did not propose generic reassignments based on their findings.

Micrathena orb-weavers in North and South America also have hardened abdomens with variously shaped spines, but they are not closely related to Gasteracantha within the orb-weaver family.

=Species=

{{as of|2021|11}}, the genus Gasteracantha contains 69 species and 18 subspecies:

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Gallery

Spiny_backed_orbweaver_spider.jpg|G. cancriformis

Hasselt's spiny spider, gasteracantha hasselti - Kaeng Krachan National Park.jpg|G. hasselti
Krachan National Park, Thailand

Gasteracantha - Spiny orb-weavers.jpg |G. geminata
Lalbagh Botanical Garden, Bangalore, India

20111029 DSC 0030 (10191378843).jpg |G. dalyi
Karnataka, India

Gasteracantha quadrispinosa by Danny S.-1.JPG |G. quadrispinosa
Queensland, Australia

Spider with fangs - Mecufi district of Mozambique, close to the sea coast.jpg |G. falcicornis
Mecúfi District, Mozambique

References

{{Reflist}}

External links

{{Commons}}

{{Wikispecies|Gasteracantha}}

  • [https://www.youtube.com/watch?v=Zw9UUuUpmcQ Video of a spiny orbweaver's heart beating]

{{Taxonbar|from=Q2175752}}

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Category:Araneidae

Category:Araneomorphae genera

Category:Cosmopolitan spiders

Category:Taxa named by Carl Jakob Sundevall