Loxosceles arizonica

Gertsch & Mulaik, 1940

Arizona brown spider, Arizona Recluse

Loxosceles arizonica, commonly known as the Arizona brown spider or Arizona Recluse, is a recluse spider in the Sicariidae. Field studies indicate that ants constitute its primary prey, particularly species in the Novomessor and Camponotus. Like other Loxosceles species, it possesses cytotoxic venom capable of causing necrotic , though documented cases of envenomation in humans appear limited compared to more widespread relatives such as L. reclusa.

Pronunciation

How to pronounce Loxosceles arizonica: /lɒkˈsɒsɪliːz æˌrɪˈzoʊnɪkə/

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Identification

Positive identification requires examination of arrangement: six eyes in three pairs forming a U-shaped pattern, with distinct spacing between each pair. The characteristic violin-shaped marking on the may be present but is variable and unreliable as a sole diagnostic feature. Similar markings occur in numerous unrelated spider . Distinguishing L. arizonica from other southwestern Loxosceles species and from harmless brown-colored spiders requires expert examination of specimens.

Distribution

Southwestern United States, primarily Arizona. Distribution records from GBIF confirm occurrence in the USA.

Diet

Ants, particularly in the Novomessor and Camponotus.

Ecological Role

of ants in arid and semi-arid southwestern .

Human Relevance

Possesses medically significant cytotoxic venom capable of causing necrotic skin (), though documented human envenomation cases appear less common than with more widespread recluse . Misidentification with harmless brown spiders and other Loxosceles species is frequent.

Similar Taxa

Loxosceles reclusaOverlaps in general appearance and arrangement; distinguished by geographic range (central and southeastern USA versus southwestern USA for L. arizonica) and subtle morphological differences requiring expert identification.
Loxosceles desertaAnother southwestern recluse with similar preferences and appearance; requires detailed morphological examination for reliable separation.
Non-venomous brown spiders (various families)Many spiders share brown coloration and superficial markings; distinguished definitively by the six- arrangement unique to Sicariidae among common household spiders.