Diagnosis.  - Metasomal segments I-IV without short, reddish, intercarinal setae ventrally;  metasomal segment III length/width ratio in adult males 1.8 or less, junveniles and adult females 1.7 or less, immatures 1.6 or less; carapace length/pectin length ratio in adult females 1.2 or more; pectinal teeth in females 22 or fewer (rarely 23 or 24); adult carapace length usually less than 6.5 mm in males and 7.0 mm in females.

Comparisons. -  The closely related genus Paruroctonus lacks the numerous short, reddish, intercarinal ventral setae on metasomal segments I-IV, and differs significantly in the other four characters above (see Haradon 1983).

Subordinate taxa. - The genus Smeringerus includes four species (one of which is divided into two subspecies).  

Distribution. - Western North America, southern Canada southward into Mexico.  The genus is represented in California by the following taxa: