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Evarcha bakorensis

From Wikipedia, the free encyclopedia

Evarcha bakorensis
The related Evarcha arcuata
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Chelicerata
Class: Arachnida
Order: Araneae
Infraorder: Araneomorphae
Family: Salticidae
Subfamily: Salticinae
Genus: Evarcha
Species:
E. bakorensis
Binomial name
Evarcha bakorensis
Rollard & Wesołowska, 2002
Synonyms
  • Evawes bakorensis (Rollard & Wesołowska, 2002)

Evarcha bakorensis is a species of jumping spider in the genus Evarcha that lives in Guinea, Ivory Coast and Nigeria. It thrives in savanna grasslands. The species was first described in 2002 by Christine Rollard and Wanda Wesołowska. The spider is small, with a cephalothorax measuring between 1.6 and 1.8 mm (0.06 and 0.07 in) long and an abdomen that is between 1.3 and 1.9 mm (0.05 and 0.07 in) long. The female is larger than the male. The cephalothorax has a light brown topside, or carapace, yellow underside, or sternum, and darker sides. The abdomen is greyish-brown or brown and has a lighter pattern on it. The spider has generally brown legs. It has distinctive copulatory organs. The female has a large membrane in the centre of its epigyne while the male has a straight and blunt tibial apophysis, or projection on its palpal tibia.

Taxonomy

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Evarcha bakorensis is a species of jumping spider that was first described by Christine Rollard and Wanda Wesołowska in 2002.[1] It was one of over 500 species identified by the Polish arachnologist Wesołowska during her career, making her one of the most prolific authors in the field.[2] They allocated it to the genus Evarcha, that had been first circumscribed by Eugène Simon in 1902.[3] The genus is one of the largest, with members found on four continents.[4] The species is named for the place that was first found.[5]

In 1976, Jerzy Prószyński had placed the genus Evarcha in the subfamily Pelleninae, along with the related genera Bianor and Pellenes.[6] In Wayne Maddison's 2015 study of spider phylogenetic classification, the genus Evarcha was moved to the subtribe Plexippina.[7] This is a member of the tribe Plexippini, in the subclade Simonida in the clade Saltafresia.[8] It is closely related to the genera Hyllus and Plexippus.[9] Analysis of protein-coding genes showed it was particularly related to Telamonia.[10] In the following year, in 2016, Prószyński added the genus to a group of genera named Evarchines, named after the genus, along with Hasarinella and Nigorella based on similarities in the spiders' copulatory organs.[11]

Prószyński placed the spider in a new genus Evawes in 2018 based on its copulatory organs and the way that they differ from other Evarcha spiders. The new genus name is a combination of Evacha and Wesołowska.[12] This designation is not widely accepted and the species remains in the Evarcha genus in the World Spider Catalog.[1][13] At the same time, Prószyński also noted the similarity between the species and those in the genus Pellenes, speculating that its relationship with other jumping spiders may not be closed.[14]

Description

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Evarcha bakorensis is small with looks that are typical for the genus. The spider's body is divided into two main parts: an oval cephalothorax and an egg-shaped abdomen. The male has cephalothorax that measures typically 1.6 mm (0.06 in) long and 1.1 mm (0.04 in) wide.[15] The carapace, the hard upper part of the cephalothorax, is convex and high. Largely light brown with darker sides, it is covered with delicate colourless hairs. It has a dark brown eye field with small fawn scales between some of the eyes. Some examples also have a triangular patch between the eyes. The underside of the cephalothorax, or sternum, is dark yellow or yellowish-brown. Its mouthparts are distinctive. They are generally light brown. The chelicerae have two teeth to the front and a single tooth to the back, while the labium and maxillae have light tips. The spider's face, or clypeus, has a covering of fawnish-yellow hairs.[16][17] Some examples have a reddish-orange band on the clypeus, similar to the related Evarcha ignea.[18]

The male has an abdomen that is smaller than the carapace, measuring between 1.3 and 1.4 mm (0.05 and 0.06 in) long and 0.9 and 1 mm (0.04 and 0.04 in) wide.[15][16] It is a brown oval with a pattern consisting of a lighter patch shaped like a leaf and four white patches on its back. The underside is grey or yellowish. The spider has dark spinnerets. Its legs are generally brown. The first pair are darker.[17]

The spider has a distinctive copulatory organs with yellowish-brown pedipalps and a palpal tibia that has a small number of long bristles. The tibia has a single straight, wide and blunt protrusion, or tibial apophysis. The palpal bulb is rounded with a large protusion at its base. The embolus emanating from the top of the bulb is thin and curved.[15] It is the spider's copulatory organs that most help identify it. For example, the blunt end to the spider's tibial apophysis helps distinguish it from the related Evarcha awashi, Evarcha carbonaria and Evarcha ignea.[18][19][20]

The female is larger than the male, with a cephalothorax that is between 1.6 and 1.8 mm (0.06 and 0.07 in) in length and typically 1.3 mm (0.05 in) wide. The abdomen has a length between 1.7 and 1.9 mm (0.07 and 0.07 in) and a width of between 1.3 and 1.5 mm (0.05 and 0.06 in).[17] It has a light brown carapace with darker sides similar to the male, with the area around the eyes black and a covering of colourless hairs apart from long brown bristles near the eyes themselves. The sternum is yellow. The chelicerae and brown while the labium and maxillae are brownish with light tips.[21] The clypeus is covered in orange hairs.[22]

The abdomen is greyish-brown on top and yellow with a hint of grey underneath. The top has a lighter pattern of a large butterfly-shape patch on forward half, three chevrons to the rear, and for round spots at the very back. The underside is marked by dots that form four lines. The spinnerets are yellowish-grey. The spider has patches of yellow on its otherwise brown legs, which have dark hairs and spines. It has a large membrane in the centre of its epigyne. The copulatory openings lead to sclerotized receptacles, or spermathecae,[17]

Distribution and habitat

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Evarcha spiders live across the world, although those found in North America may be accidental migrants.[23] Although the genus is found across Africa, Evarcha bakorensis has only been found living in Guinea, Ivory Coast and Nigeria.[1] The male holotype for the species was found in 1956 on the road to Bakoré, Guinea, at an altitude of 500 m (1,600 ft) above sea level.[5] The first examples found in Nigeria were discovered in 1974 in both the International Institute of Tropical Agriculture in Ibadan and the Borgu Game Reserve in Kwara State. Other specimens were subsequently found near Mokwa.[15] In 1975, the first examples were collected in Ivory Coast.[22]

The first example of the species was found in grasses of the Andropogon genus and subsequent examples have been often found living in savanna grasslands.[24] One example was found in 14 year old savanna regrowth. Some Evarcha bakorensis spiders have also been found living in debris left on the side of a river from flooding.[15]

References

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Citations

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  1. ^ a b c World Spider Catalog (2017). "Evarcha bakorensis Rollard & Wesolowska, 2002". World Spider Catalog. 18.0. Bern: Natural History Museum. Retrieved 19 July 2017.
  2. ^ Wiśniewski 2020, p. 6.
  3. ^ Rollard & Wesołowska 2002, p. 60.
  4. ^ Prószyński 2018, p. 132.
  5. ^ a b Rollard & Wesołowska 2002, p. 288.
  6. ^ Maddison & Hedin 2003, p. 540.
  7. ^ Maddison 2015, p. 250.
  8. ^ Maddison 2015, pp. 246, 280.
  9. ^ Maddison, Bodner & Needham 2008, p. 56.
  10. ^ Maddison & Hedin 2003, p. 536.
  11. ^ Prószyński 2017, p. 51.
  12. ^ Prószyński 2018, p. 153.
  13. ^ Kropf et al. 2019, p. 445.
  14. ^ Prószyński 2018, p. 134.
  15. ^ a b c d e Wesołowska & Russell-Smith 2011, p. 568.
  16. ^ a b Rollard & Wesołowska 2002, p. 289.
  17. ^ a b c d Wesołowska & Russell-Smith 2011, p. 569.
  18. ^ a b Wesołowska & Cumming 2008, p. 175.
  19. ^ Wesołowska & Tomasiewicz 2008, p. 11.
  20. ^ Wesołowska 2012, p. 204.
  21. ^ Wesołowska & Russell-Smith 2011, pp. 569, 612.
  22. ^ a b Wesołowska & Russell-Smith 2022, p. 23.
  23. ^ Maddison & Hedin 2003, p. 543.
  24. ^ Wesołowska & Russell-Smith 2022, p. 136.

Bibliography

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