Orsonwelles

Orsonwelles
Orsonwelles graphicus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Arachnida
Order: Araneae
Suborder: Araneomorphae
Family: Linyphiidae
Genus: Orsonwelles
Hormiga, 2002
Type species
Orsonwelles polites
Hormiga, 2002
Diversity
13 species
Range of Orsonwelles in the Hawaiian Islands

Orsonwelles is a genus of spiders belonging to the family Linyphiidae. The 13 known species, all native to the Hawaiian Islands, include the largest known linyphiids, reaching maximum body lengths of 14 millimeters (0.55 inches), an example of island gigantism. Each species occurs on a single island, often at high elevations. The spiders have large jaws, and are generalist predators. The genus name honors the actor and film-maker Orson Welles and many of the species names commemorate elements from Welles' films, radio productions, or roles. One species has not been collected since the 1890s, and is believed to be extinct.

Description

Orsonwelles spiders are large, with females ranging from 8.06 to 14.07 mm in body length, and males ranging from 6.2 to 11.35 mm; the largest individuals recorded are in the species O. malus. The jaws (chelicerae) are large and massive, with many cheliceral teeth.[1] Orsonwelles contains the largest known members of the family Linyphiidae, with the next largest, Laminacauda gigas, attaining body lengths of just under 10 mm. The large size is an example of island gigantism, a phenomenon where lineages on islands evolve large body size relative to mainland relatives.[2] The carapace and abdomen are dark brown or gray with a light band running down the middle of the carapace, and light blotches or chevron-shaped markings sometimes present on the dorsal surface of the oval-shaped abdomen.[3] The femurs (second limb segment) of the third and fourth leg pairs possess one to six trichobothria (large sensory hairs), a trait unique among the Linyphiidae: all others lack femoral trichobothria.[1]

Natural history

Orsonwelles spiders primarily live in remnants of rainforests and mixed mesic forests. Many are restricted to higher elevations, where environmental disturbance is less severe and non-native species less common, but some species occur in disturbed areas as low as 500 m (1,600 ft) above sea level. Individuals are nocturnal, remaining hidden during the day and appearing upside down in the center of their webs at night. They are generalist predators, and feed on a variety of arthropods including on moths and terrestrial amphipods.[4] Their webs often contain native Hawaiian species of Argyrodes (A. hawaiiensis, A. ilipoepoe, and A. laha): tiny spiders (around 3 mm body length) which are kleptoparasites of Orsonwelles, feeding on remains caught in the web. Orsonwelles webs typically contain 10 to 25 individual Argyrodes per web, and may have up to 60.[5]

Species

The first species now classified in Orsonwelles were described in 1900 by the French naturalist Eugène Simon, who described Labulla torosa and Labulla graphica, in the genus Labulla (now restricted to certain Eurasian species).[6] In 2002, eleven new species were described by Gustavo Hormiga of George Washington University who established a new genus, Orsonwelles, to encompass them and Simon's two species (with torosa and graphica becoming torosus and graphicus since Orsonwelles is a masculine noun). The genus name commemorates actor and filmmaker Orson Welles,[7] and the names of the species described by Hormiga derive from or allude to names of various productions or roles of Welles.[8] Each species of Orsonwelles is endemic to a single island, with Kauai harboring the most (six species), followed by Oahu with three species, Molokai with two, and Maui and the Island of Hawaii with a single species each.[9][10] The species O. torosus of Kauai is believed to be extinct, as it was last collected in the 1890s and has not been collected since.[11]

Species Distribution Etymology[8]
Orsonwelles ambersonorum Hormiga, 2002 Oahu Named for Welles' 1942 film The Magnificent Ambersons
Orsonwelles arcanus Hormiga, 2002 Oahu Named for Welles' 1955 film Mr. Arkadin (also known as Confidential Report; arcanus meaning "hidden" or "confidential" in Latin)
Orsonwelles bellum Hormiga, 2002 Kauai Named for Welles' 1938 radio drama The War of the Worlds (bellum meaning "war" in Latin)
Orsonwelles calx Hormiga, 2002 Kauai Named for Harry Lime, Welles' character in Carol Reed's 1949 film The Third Man (calx meaning "lime" in Latin)
Orsonwelles falstaffius Hormiga, 2002 Maui Named for the character Falstaff, played by Welles in his 1966 film Chimes at Midnight
Orsonwelles graphicus (Simon, 1900) Hawaii Graphicus, Latin: "belonging to painting or drawing"
Orsonwelles iudicium Hormiga, 2002 Kauai Named for Welles' 1962 film The Trial (iudicium meaning "judgement" or "trial" in Latin)
Orsonwelles macbeth Hormiga, 2002 Molokai Named for Welles' 1948 film Macbeth
Orsonwelles malus Hormiga, 2002 Kauai Named for Welles' 1958 film Touch of Evil (malus meaning "evil" in Latin)
Orsonwelles othello Hormiga, 2002 Molokai Named for Welles' 1952 film Othello
Orsonwelles polites Hormiga, 2002 Oahu Named for Welles' 1941 film Citizen Kane (polites meaning "citizen" in Greek)
Orsonwelles torosus (Simon, 1900) Kauai Torosus, Latin for "muscular" or "fleshy"
Orsonwelles ventus Hormiga, 2002 Kauai Named for Welles' unfinished film The Other Side of the Wind (ventus meaning wind in Latin)

Classification

Orsonwelles is in the family Linyphiidae a large family of spiders with global distribution. The closest relative of Orsonwelles is unknown.[10]

See also

References

  1. 1 2 Hormiga 2002, pp. 381–386.
  2. ↑ Hormiga 2002, pp. 377.
  3. ↑ Hormiga 2002, pp. 381–384.
  4. ↑ Hormiga 2002, p. 381.
  5. ↑ Rivera, Malia; Gillespie, Rosemary G. (2010). "New species of endemic kleptoparasitic spiders of the genus Argyrodes (Araneae: Theridiidae) in the Hawaiian Islands". Pacific Science. 64 (2): 221–231. doi:10.2984/64.2.221.
  6. ↑ Simon, Eugène (1900). Arachnida. Pages 443–519 in Fauna Hawaiiensis, or the zoology of the Sandwich Isles: Being results of the explorations instituted by the Royal Society of London promoting natural knowledge and the British Association for the Advancement of Science, London. Vol. II. Royal Society, London.
  7. ↑ Hormiga 2002, p. 388.
  8. 1 2 Hormiga, Gustavo (2002). "Orsonwelles, a new genus of giant linyphiid spiders (Araneae) from the Hawaiian Islands" (PDF). Invertebrate Systematics. 16: 369–448.
  9. ↑ Hormiga 2002, p. 378.
  10. 1 2 Hormiga, Gustavo; Arnedo, Miquel; Gillespie, Rosemary G. (2003). "Speciation on a Conveyor Belt: Sequential Colonization of the Hawaiian Islands by Orsonwelles Spiders (Araneae, Linyphiidae)". Systematic Biology. 52 (1): 70–88. doi:10.1080/10635150390132786.
  11. ↑ Hormiga 2002, p. 391.
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