Is the black form (yellow on black) only found in the Northeast?

Townes & Townes (1978) say: "There is considerable regional variation in color. Specimens from New England and adjacent parts of New York are darkest, from which area the populations are progressively paler toward the west and south. Darker individuals have the ground color blackish brown, which towards the south and the west becomes fulvous brown or fulvous. Yellow markings are most restricted in the northeastern part of the range, most extensive in the west. Specimens from Arizona and New Mexico have the yellow bands on the abdomen unusually wide, but the yellow on the thorax of only moderate extent. In New England and adjacent parts of New York, the yellow banding on the abdomen is usually restricted to the basal 3-5 tergites. The wings are rather uniformly brown, except that in specimens from the Great Plains and foothils of the Rocky Mts. the apex of the front wing is hyaline."

I find it strange that they mention Arizona because they listed no specimens from Arizona nor had any dots in Arizona on their map. They named a western (WA,CA, NV, UT, CO, NM) subspecies (sicca), but that is distinguished in the key on the basis of the spacing of the hairs on the face and hind femur (sparcer in sicca).