Sicariidae

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Sicariidae
Brown recluse spider, Loxosceles reclusa.jpg
Brown recluse spider (Loxosceles reclusa)
Scientific classification edit
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Chelicerata
Class: Arachnida
Order: Araneae
Infraorder: Araneomorphae
Superfamily: Scytodoidea
Family: Sicariidae
Keyserling, 1880[1]
Genera

See text.

Diversity[2]
3 genera, 163 species
Distribution.sicariidae.1.png
Synonyms[1]

Loxoscelidae

Sicariidae is a family of six-eyed venomous spiders known for their potentially necrotic bites. The members of this family are haplogyne, possessing unsclerotised genitals in females. The family consists of three genera and about 160 species. Well known spiders in this family include the brown recluse spider, Loxosceles reclusa, and the six-eyed sand spider, Hexophthalma hahni.

Description[edit]

The genus Loxosceles, commonly known as recluse spiders or violin spiders, is distributed nearly worldwide in warmer areas. The genera Hexophthalma and Sicarius, sand spiders or assassin spiders, are desert spiders that live in the Southern Hemisphere, in (southern Africa and South and Central America respectively), known primarily for their self-burying behavior. All have six eyes arranged in three groups of two (dyads) and the violin spiders are usually brownish with a darker brown characteristic violin marking on the cephalothorax. Hexophthalma and Sicarius resemble the crab spiders of the family Thomisidae and lack this marking. Individuals of these two genera can live for as much as 15 years, which makes these among the longest-lived araneomorphae spiders (some tarantulas can live well over 20–30 years.) Most Loxosceles can live for one and a half to two years. Members of all three genera can live for very long times without food or water.

Taxonomy[edit]

The family was first described by Eugen von Keyserling in 1880. Classically (e.g. in Eugène Simon's account in 1893), it contained many genera, but by 1991 had been reduced to one, Sicarius, with Loxosceles placed in its own family, Loxoscelidae. Platnick et al. reduced Loxoscelidae to a subfamily of Sicariidae, producing a family of two genera, each in its own subfamily.[3][4] A phylogenetic study in 2017 showed that the African species of Sicarius were distinct, and placed them in the revived genus Hexophthalma. The relationship found between the genera is shown in the following cladogram:[3]

Sicariidae
Loxoscelinae

Loxosceles

Sicariinae

Hexophthalma

Sicarius

Genera[edit]

As of July 2018, the World Spider Catalog accepted the following genera:[1]

Venom[edit]

All genera are able to produce sphingomyelinase D or related proteins. This is a potent tissue-destroying substance, unique to the family among spiders, and otherwise only found in a few pathogenic bacteria. The venom of many Sicariidae species is highly necrotic (dermonecrotic) in effect, capable of causing lesions (open sores) as large as a US quarter (about one inch or 25 mm in diameter). The wounds take a long time to heal and they may require skin grafts. If these open wounds get infected there can be serious consequences. Rarely, the venom is carried by the blood stream into internal organs causing systemic effects. Bites from most of the Neotropical species of Sicarius are not known to display dermonecrotic activity, although proteins of the sphingomyelinase D family are found in the venom.[5][3]

See also[edit]

References[edit]

  1. ^ a b c "Family Sicariidae Keyserling, 1880", World Spider Catalog, Natural History Museum Bern, retrieved 2018-07-17
  2. ^ "Currently valid spider genera and species", World Spider Catalog, Natural History Museum Bern, retrieved 2018-07-17
  3. ^ a b c Magalhães, I.L.F.; Brescovit, A.D. & Santos, A.J. (2017), "Phylogeny of Sicariidae spiders (Araneae: Haplogynae), with a monograph on Neotropical Sicarius", Zoological Journal of the Linnean Society, 179 (4): 767–864, doi:10.1111/zoj.12442
  4. ^ Platnick, N.I.; Coddington, J.A.; Forster, R.R. & Griswold, C.E. (1991), "Spinneret morphology and the phylogeny of haplogyne spiders (Araneae, Araneomorphae)", American Museum Novitates, 3016: 1–73
  5. ^ Binford, Greta J.; Wells, Michael A. (2003). "The phylogenetic distribution of sphingomyelinase D activity in venoms of Haplogyne spiders" (PDF). Comparative Biochemistry and Physiology B. 135: 25–33.

External links[edit]