The Arizona brown spider, scientifically known as Loxosceles arizonica, is a venomous spider species found in the southwestern United States, primarily in the state of Arizona. It belongs to the family Sicariidae, which is commonly referred to as “recluse spiders” due to their elusive nature and tendency to hide away in secluded areas.
Taxonomy and Classification
The Arizona brown spider was first described in 1961 by Mulaik and Gertsch, who identified it as a distinct species within the genus Loxosceles. The genus Loxosceles consists of venomous spiders commonly known as “brown spiders” or “recluse spiders.” These spiders are known for their characteristic violin-shaped markings on the cephalothorax, which is why they are often referred to as “violin spiders.”
Physical Description
The Arizona brown spider is relatively small compared to other spider species, with adults typically measuring around 0.25 to 0.5 inches (6 to 12 mm) in body length. Like other recluse spiders, it has six eyes arranged in three pairs, unlike most spiders which have eight eyes. The cephalothorax and abdomen of the spider are uniformly colored in shades of brown, ranging from light tan to dark brown.
One distinguishing characteristic of the Arizona brown spider is the presence of a dark violin-shaped marking on the cephalothorax. This marking is not always clearly defined, and it may vary in shape and intensity of coloration among individuals. The legs are long and slender, and the spider has a characteristic “drumstick” appearance when viewed from the side.
Distribution and Habitat
The Arizona brown spider is endemic to the southwestern United States, with its primary range centered in the state of Arizona. It can also be found in neighboring states such as New Mexico, Nevada, Utah, and California. Within its range, the spider prefers arid and semi-arid habitats, including deserts, scrublands, and rocky areas.
These spiders are known to be particularly abundant in human-altered environments such as buildings, where they often seek refuge in dark and undisturbed areas. They are capable of establishing populations indoors, especially in houses, garages, and storage areas.
Behavior and Venom
Arizona brown spiders are nocturnal and tend to be more active during the warmer months of the year. During the day, they hide in dark and secluded places, such as cracks in walls, under furniture, or inside shoes. At night, they emerge to search for prey, which primarily consists of small insects and other spiders.
Like other recluse spiders, the Arizona brown spider possesses venom that contains a mixture of enzymes and proteins. The venom is primarily used to immobilize and digest prey. While the bite of an Arizona brown spider can be painful, it is usually not life-threatening to humans. However, in some cases, it can lead to necrotic lesions, causing tissue damage and potentially requiring medical attention.
Conservation Status
The conservation status of the Arizona brown spider has not been specifically assessed. However, as a relatively common and adaptable species, it does not face significant conservation concerns. Its populations may fluctuate depending on habitat alterations and the presence of suitable prey sources, but overall, the species is considered to be stable.
Interaction with Humans
Due to their venomous nature, Arizona brown spiders are often regarded with caution and sometimes fear by humans. While they are capable of biting if provoked or trapped, they generally try to avoid contact with humans. To minimize the risk of encountering these spiders, it is recommended to take precautions such as shaking out clothing and bedding that has been stored for a long time.
If a bite occurs, it is advisable to seek medical attention to ensure proper wound care and potential administration of antivenom, although such cases are relatively rare. Proper identification of the spider responsible for the bite can aid in appropriate medical treatment and reduce unnecessary concern.