TWO NEW SUBSPECIES OF CROTAPHYTUS (SAURIA: IGUANIDAE) Nathan M. Smiths and Wilmer W. Tanner^ Abstract. — Analysis of the Crotaphytus collaris complex reveals at least eight subspecies in two distinct groupings. The co//arzi-complex containing C. c. auriceps, C. c. baileyi, C. c. fuscus, and C. c. collaris lies essentially to the east of the Colorado River. The greatest portion of the western-complex containing C. c. bicinctores, C. i. vestigium, C. c. dickersonae and C. i. insularis lies to the west of the Colorado River except through western Arizona and northern Mexico. Two previously undescribed subspecies, C. c. bicinctores and C. i. vestigium, are de-scribed and named. This paper presents a brief portion of an extensive study of the western collared lizards from the Great Basin and the Baja California Peninsula. The complete report will soon appear in the Biological Series of the Brigham Young University Science Bulletin. The range of the western collared lizard, Crotaphytus collaris baileyi, includes a vast area of the western United States and Mexico. One of us (Tanner, in Fitch and Tanner, 1951; Ingram and Tanner, 1971) has suspected for a number of years that the lizards occurring in this vast area represent a heterogenous population. Stejneger (1890) described Crotaphytus baileyi as a species; however, as data became available it was recognized to be a western subspecies of Crotaphytus collaris Say (1823), the form found east of the Con-tinental Divide. Two insular forms, Crotaphytus dickersonae Schmidt (1922) from Tiburon Island, and Crotaphytus insularis Van Den-burgh and Slevin (1921) from Angel de la Guardia Island, Mexico, although given species rank, have long been recognized as closely related to C. c. baileyi. Allen (1933) referred to the collared lizards from Tiburon Island as C. c. dickersonae. Burt (1928) considered all collared lizards to be closely related. Fitch and Tanner (1951) established C. c. auriceps from the upper Colorado River Basin. Ingram and Tanner (1971) reaffirmed C. c. auriceps as a subspecies and, upon redefinition of the char-acteristics of C. c. baileyi, established C. c. fuscus as a subspecies found in the Chihuahuan Desert south of the range of baileyi. The type locality for that subspecies being 6.5 miles N and 1.5 miles W of Chihuahua City, Chihuahua, Mexico. The techniques described by Ingram and Tanner (1971) were used to compare four subspecies of the western-complex with four subspecies of the collaris-complex. This technique permitted both an intercomplex and an intracomplex comparison. Relationships To determine relationships, Ward's Minimum Variance Cluster Analysis (Wishart, 1968) was used to group lizards in clusters of highest morphological similarity. Lizards were chosen to represent 'Department of Zoology, Brigham Young University, Provo, Utah 84601 . 25
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