Document Type


Publication Date

Fall 12-2-1953


Preliminary collections were made in the summer of 1951 in an effort to determine whether altitudinal zonation exists among spiders. These collections were continued and completed in the summer of 1952. A total of 1212 determined specimens represent the basis for this thesis. Despite the fact that collections were made during two summers, the number of specimens obtained for some species was very small, making definite zonal restriction difficult. On the basis of the entire collection, however, altitudinal zonation was quite evident. Sixty-nine of the total 101 species occurred in only one zone. That such a high proportion of species are unizonal is significant and can only be interpreted as indicating that spiders do conform, at least to some extent, to altitudinal zones. The results of this study should not be accepted as conclusive, however. Intensive and extensive collecting will be necessary to validate the present data. On the basis of field experience three species were found to be common and characteristic of certain habitats. Pardosa sternalis can always be found in meadows of the plains zone during the summer months. Pardosa yavapa is also found in meadows but prefers the foothills and montane zones. Agelenopsis utahana is easily found in buildings in the plains zone. Three female specimens representing the genera Allotheridion, Paraphidippus and Haplodrassus have not been identified. They are probably new species and will be described and published after ascertaining that they have not been previously recorded.