Trichonephila
Female Trichonephila clavipes
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Chelicerata
Class: Arachnida
Order: Araneae
Infraorder: Araneomorphae
Family: Nephilidae
Genus: Trichonephila
Dahl, 1911[1]
Type species
T. clavipes
(Linnaeus, 1767)
Species

12, see text

Trichonephila is a genus of golden orb-weaver spiders that was first described by Friedrich Dahl in 1911, as a subgenus of Nephila.[2] Trichonephila was elevated to the level of genus (new rank) by Kuntner et al. in 2019.[3] The genus Trichonephila belongs to the Nephilidae family.

Distribution and habitat

Regions and seasons

The genus Trichonephila can be found living in Africa, Oceania, Asia, Central America, the West Indies, South America, and the southeastern region as well as the gulf states in the United States.[4][5] This genus of spiders like to make its web where prey is fruitful, often in open wooded areas, between tree branches, shrubs, tall grasses, and around light fixtures.  The two sexes can be found more actively in different parts of the year, with the males being more abundant in the months of July to September, while the females are most abundant late into fall. [5]

Species

As of August 2019 it contains twelve species and fourteen subspecies, found in Africa, Oceania, Asia, and over all the Americas:[1]

Body

External anatomy

The Orb Weavers body is composed of two separate regions: Prosoma (anterior end) and Opisthosoma (posterior end).[5] Both regions are responsible for their own functions and are linked together by a narrow stalk called a pedicil.[5] The prosoma of the spider is segmented and protected by the sternum, carapace, and a plate on both the dorsal and ventral side.[6]  The prosoma is the location of the central nervous system, and it oversees nervous integration, movement and food uptake.[4] Also connected are the eyes, chelicerae, maxilla, sternum, fangs and four pairs of legs.[4] Its unsegmented soft counterpart, the opisthosoma, contains the spinnerets while also being held accountable for digestion, circulation, respiration, reproduction, and silk production.[4][6]

Behavior

Sexual dimorphism

When comparing the sizes of genders of the genus Trichonephila, you will find that the female spiders have the size advantage and are the dominant sex.[7] One reason for the size difference amongst the genus is that following their mating sequence, the females will sometimes perform cannibalistic actions towards their mating partner and kill them.[8] Male spiders will fight over a female partner, leaving the dominant spider to successfully mate and potentially be killed by the female afterwards. Over the past few decades, its believed that female spiders have selectively and actively chosen to have a small male counterpart.[8][7]

Courtship dance

The courtship dance is a mating dance males enact, attempting to be accepted by the females as a mate.[7] [8]This dance provides multiple functions for the spider rather than just for reproduction. To begin the courtship, a male must find a female’s web and make vibrations to let her know he’s not prey, it is very common for the male to be mistook as prey and eaten alive by the females before or after they mate.[7] The vibrating of the web reduces the risk of aggravating the female.[9]

Environmental adaptations

The genus Trichonephila must be able to adapt to environmental conditions in order to thrive in their environments. The males being the sex that leave their web and traverse for a female, have more competition when it comes to reproduction, food, and shelter.[10] The trichonephila genus of spiders has a yellow-colored web and this is due to the Xanthurenic acid content in the web, believed to assist the spider in attracting its prey.[11] The genus also has its own adaptation when it comes to heavy rain, unlike its relatives. Spiders will hang off its web from only its fourth pair of legs, which in turn reduces rain impact damage and helps with draining the water off the web.[12] A new recent enemy introduced to the genus that has considerably shrunk the size of the spiders, are pesticides, as spiders have been reported smaller in size when living in areas present.[13]

References

  1. 1 2 "Gen. Trichonephila Dahl, 1911". World Spider Catalog Version 20.0. Natural History Museum Bern. 2019. doi:10.24436/2. Retrieved 2019-09-06.
  2. ↑ Dahl, F. (1911). "Die Verbreitung der Spinnen spricht gegen eine frühere Landverbindung der Südspitzen unsrer Kontinente". Zoologischer Anzeiger. 37: 270–282.
  3. ↑ Kuntner, Matjaž; Hamilton, Chris A.; Cheng, Ren-Chung; Gregorič, Matjaž; Lupše, Nik; Lokovšek, Tjaša; Lemmon, Emily Moriarty; Lemmon, Alan R.; Agnarsson, Ingi; Coddington, Jonathan A.; Bond, Jason E. (2019). "Golden orbweavers ignore biological rules: phylogenomic and comparative analyses unravel a complex evolution of sexual size dimorphism". Systematic Biology. 68 (4): 555–72. doi:10.1093/sysbio/syy082. PMC 6568015. PMID 30517732. S2CID 54562033.
  4. 1 2 3 4 Bartlett, Troy (2013). "Family Araneidae - Orb Weavers". bugguide.net. Retrieved 2022-04-05.
  5. 1 2 3 4 Weems, Jr., H.V. (2001). "golden silk spider". entnemdept.ufl.edu. Retrieved 2022-04-22.
  6. 1 2 Foelix, Rainer F. (2011). Biology of Spiders. Oxford University Press. pp. 1–49 – via Academia.edu.
  7. 1 2 3 4 Silva, Amanda Vieira da (2020-02-19). "Web wars: males of the golden orb-web spider Trichonephila clavipes escalate more in contests for mated females and when access to females is easier". {{cite journal}}: Cite journal requires |journal= (help)
  8. 1 2 3 Vollrath, Fritz; Parker, Geoff A. (1992). "Sexual dimorphism and distorted sex ratios in spiders". Nature. 360 (6400): 156–159. Bibcode:1992Natur.360..156V. doi:10.1038/360156a0. ISSN 1476-4687. S2CID 4320130.
  9. ↑ wignall, anne (2021). "Male courtship reduces the risk of female aggression in web-building spiders but varies in structure". Retrieved 2022-04-05.
  10. ↑ Vollrath, Fritz; Selden, Paul (2007-12-01). "The Role of Behavior in the Evolution of Spiders, Silks, and Webs". Annual Review of Ecology, Evolution, and Systematics. 38 (1): 819–846. doi:10.1146/annurev.ecolsys.37.091305.110221. ISSN 1543-592X.
  11. ↑ Fujiwara, Masayuki; Kono, Nobuaki; Hirayama, Akiyoshi; Malay, Ali D.; Nakamura, Hiroyuki; Ohtoshi, Rintaro; Numata, Keiji; Tomita, Masaru; Arakawa, Kazuharu (2021). "Xanthurenic Acid Is the Main Pigment of Trichonephila clavata Gold Dragline Silk". Biomolecules. 11 (4): 563. doi:10.3390/biom11040563. ISSN 2218-273X. PMC 8070366. PMID 33921320.
  12. ↑ Barrantes, Gilbert; Masis, Denisse Sanchez (2021). "Spiders hanging out in the rain". Arachnology. 18 (7): 778–781. doi:10.13156/arac.2020.18.7.778. ISSN 2050-9928. S2CID 232210498.
  13. ↑ jung, jong-kook (2020). ":: Korean Journal of Applied Entomology ::". entomology2.or.kr. 59 (3). doi:10.5656/KSAE.2020.07.0.034. Retrieved 2022-04-05.
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