Sicariidae - Loxosceles arizonica
Size: 6.00 mm (female)
Group Guild Status
Trogloxene Predator Uncommon
This spider is one of the five brown spider species (Loxosceles) native to Arizona. The eastern brown recluse is a member of this genus, but occurs in Arizona only as a localized, introduced species. Species of Loxosceles are relatively common in caves in southern Arizona, sometimes occurring in large numbers as a significant predator in these habitats. Populations of these species in caves appear to be sensitive to human disturbance. Caves that have robust populations of the spiders seem to be those that receive little visitation, while the spiders never seem to be common in caves that are regularly visited by large numbers of people (RBP personal observation).
With the exception of an unconfirmed observation along one of the tour trails by KCSP staff, this species is recorded only from the Jackrabbit Shaft. The spiders live in the top part of the shaft and prey on surface invertebrates entering the shaft via small openings to the surface. The species is uncommon and has apparently not colonized the cave to any significant depth. They should also be present near the surface at the other cave surface connections, particularly in the collapsed Entrance Sink, but have not been observed in these locations to date.
Based on our observations this species is probably primarily a trogloxene in Kartchner Caverns, but Loxosceles are known to be troglophilic in other caves (RBP personal observation), and this species may occasionally be troglophilic here.
© 2019 R.B. Pape. All rights reserved.