Two Vernal Ground-Surface Arachnid Populations in Tularosa Basin, New Mexico

Abstract

Two distinctly different ground-surface arachnid populations were inadvertently discovered in the Tularosa Basin of New Mexico by the operation of alcohol-glycol charged can traps from June through August of 1972. A population just south of Alamogordo, N.M. was dominated by a web-building spider, Psilo- chorus imitatus Gertsch and Mulaik, supported by 11 relatively common spiders and a common solpugid. A much smaller population within White Sands National Monument was dominated by three prevalent spiders, Callilepis n. sp., Lycosa coloradensis Banks, and P. imitatus in that order of abundance, supported by five relatively common spiders and a common scorpion. This investigation of ground-surface arachnids in the Tularosa Basin of New Mexico was originally designed as a short term study of possible effects of natural gypsum, calcium sulfate, deposits in White Sands National Monument on coloration of solpugids occurring within the basin. The solpugid specimens collected indicated no coloration effects, but family, generic and specific makeup of the two sampled ground-surface arachnid populations were significantly dif- ferent and are considered worthy of record here. So far as I have been able to determine, only three previous publica- tions have dealt with comparative ground-surface spider populations in either adjacent or nearby plant associations or ecosystems. All three of these studies, Duffey (1962), Whitcomb, et al. (1963) and Muma (1973), were conducted in high rainfall areas. The following vernal