Loxosceles, commonly known as "recluse spiders" or "violin spiders", is distributed nearly worldwide in warmer areas. Hexophthalma and Sicarius, commonly known as "sand spiders" or "assassin spiders", live in the deserts of southern Africa and South to Central America, respectively. They are known for their self-burying behavior and the ability to go for long periods without food or water. All members have six eyes arranged in three groups of two. Violin spiders are usually brownish with a darker brown characteristic violin marking on the cephalothorax. They are also haplogyne, meaning the females possessing unsclerotised genitals. Hexophthalma and Sicarius resemble crab spiders and lack this marking. With the tarantulas, these are some of the longest living spiders, some living up to fifteen years old. Most Loxosceles can live for one and a half to two years.
Venom
All genera are able to produce sphingomyelinase D or a related tissue-destroying substance. It is unique to the family among spiders, and otherwise only found in a few pathogenic bacteria. Bites from most of the Neotropical species of Sicarius are not known to display dermonecrotic or systemic activity, except the highly venomous Sicarius ornatus which has active proteins of the sphingomyelinase D family found in the venom. The venom of many Sicariidae species is highly hemolytic and dermonecrotic, capable of destroying red blood cells and causing lesions as large as in diameter that take a long time to heal. Some require skin grafts and if the open wound gets infected, there can be even more serious consequences. Rarely, the venom is carried by the blood stream into internal organs causing systemic effects. Unlike spiders that use neurotoxins, many of the venoms used by these spiders do not have a known anti-venom.
Taxonomy
The family was first described by Eugen von Keyserling in 1880, and marked as a subfamily and synonym for "Loxoscelidae" in 1893. The status of "Loxoscelidae" as a family or subfamily of "Sicariidae" has been argued both ways. The World Spider Catalog currently accepts Loxoscelinae as a subfamily of Sicariidae, but this placement is still being debated. 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:
Genera
, the World Spider Catalog accepts the following genera:
