Ground surface spider fauna in an arid tropical community in Baja California Sur, Mexico

Abstract

Seasonal distribution, specific richness, and diversity of xeric shrub ground spiders were studied at a site in the Cape Region. Weekly collections of spiders were made in 1991-1992 using pit-fall traps. We captured 4 322 specimens in 53 families. Families with the highest number of individuals were: Miturgidae (42%) Oonopidae (23.5%), Caponiidae (8.0%), and Gnaphosidae (7.9%). The most abundant species were Syspira tigrina Chamberlin (37.1%); Oonops nov. sp. (13.7%), Scaphiella hespera Chamberlin (7.8%), and Tarsonops sternalis Chamberlin (5.2%), representing 63.7% of the total specimens captured. Gnaphosidae was the richest in species (11) followed by Salticidae (7). Species richness was nearly constant during all the year, with a small increase in summer (29) and a small decline in winter (24); seasonal diversity was also constant (H’= 3.3-3.7). The highest relative abundance occurred in spring and autumn and the highest specifi c richness was in autumn. The diversity and relative abundance of spiders were high, in spite of the high abundance of Miturgidae. Distribution of the major species had a marked seasonality.