Four species belonging to the H. tranquillus group can be found in the region, although only two of these are described in Griswold (1987). Members of this species group are unique in Habronattus in being primarily "arboreal" rather than ground-dwelling - H. hirsutus can be found both on the ground and in vegetation, while the other three species (see below) have only been collected on vegetation. All species share a well-fringed first leg with unique characteristics.

H. tranquillus - The "yellow-legged" form pictured above corresponds to the original 1901 description of H. tranquillus by the Peckham's. Although the distributional limits of this species are unclear, all available information suggests that H. tranquillus is endemic to creosote bush (Larryea) of the lower Colorado desert. The species is known to be sympatric with H. scottsdalei in this region, with H. scottsdalei found only on desert scrubs other than Larryea.

H. "scottsdalei" - The darker form pictured above corresponds to the description of Griswold (1987), but not to the original description by the Peckham's. The appropriate name for this form appears to be H. scottsdalei. The species has a desert distribution in CA and B.C.N, perhaps north to Kern county.

H. hirsutus- This species is probably the most widespread and ecologically variable species of Habronattus in the western U.S. The species can be found in habitats ranging from sea level to over 3000 meters, either on the ground on in low vegetation. H. hirsutus is easily distinguished from other Habronattus in having the ventral surface of the first femur concave and shiny black, with a narrow greenish-yellow stripe along the anterior margin. Griswold highlights several characters which are geographically variable in H. hirsutus - the photos above illustrate some of this variation in dorsal patterning and coloration.