Phylogenetic Systematics oflguanine Lizards 95 



head scales are pointed and conical, giving the head a rugose texture. This condition is 

 more strongly developed in Amblyrhynchus than in Conolophiis. All other iguanines have 

 flat or only slighdy domed dorsal head scales. In Sauromalus hispidus these scales are 

 more strongly pointed than in the other taxa, but the condition is not nearly as extreme as in 

 the Galapagos iguanas. 



Like most iguanines, crotaphytines, oplurines, and most basiliscines have relatively flat 

 head scales. Laemanctus serratus is the only basiliscine with conical head scales, but these 

 scales are confined to the casque on the back of the head and do not extend onto the frontal 

 and nasal regions as in the Galapagos iguanas. The dorsal head scales of morunasaurs are 

 variable. In Hoplocercus and Morunasaurus these scales are convex but not pointed; in 

 Enyalioides they are pointed and conical, but are relatively much smaller than those of the 

 Galapagos iguanas. Thus, the condition of the dorsal head scales in Amblyrhynchus and 

 Conolophus is not seen in any of the outgroups and must be considered apomorphic. 



Superciliaries. Etheridge and de Queiroz (1988) noted variation in the superciliary 

 scales of iguanines. In Dipsosaurus these scales are elongate anteroposteriorly and overlap 

 one another extensively, especially in the anterior portion of the row. Amblyrhynchus and 

 Sauromalus possess the opposite extreme in which the superciliaries are roughly 

 quadrangular and nonoverlapping. The remaining iguanines are intermediate, with only 

 moderate overlap of the superciliaries. Outgroup comparison indicates that the condition of 

 the superciliaries has been relatively plastic at this level of comparison, making 

 determination of its polarity ambiguous. Quadrangular, nonoverlapping superciliaries 

 occur in morunasaurs and the basiliscine Corytophanes. Elongate, strongly overlapping 

 superciHaries occur in oplurines, and an intermediate condition occurs in crotaphytines and 

 the basiliscines Basiliscus and Laemanctus. 



Suboculars. The morphology of the subocular scales is also variable in iguanines 

 (Etheridge and de Queiroz, 1988). Dipsosaurus and Ctenosaura have one long and several 

 shorter suboculars. In all other iguanines except Amblyrhynchus, which is intermediate, 

 all of the suboculars are approximately equal in size. The condition of the suboculars in the 

 four outgroups is too variable to allow inference about the polarity of this character. 

 Basiliscines, morunasaurs, and some Crotaphytus have suboculars that are subequal in 

 size. Other Crotaphytus have one moderately elongate subocular. Gambelia and oplurines 

 have one very long subocular and several much shorter ones. 



Anterior Auricular Scales (Van Denburgh, 1922). Sauromalus differs from all other 

 iguanines in the scales that border the tympanum anteriorly, the anterior auricular scales. 

 From two to five of these scales are enlarged relative to the neighboring scales and project 

 posterolaterally over the tympanum, offering protection to this delicate membrane. In all 

 other iguanines except Dipsosaurus, the anterior auricular scales are small and the 

 tympanum is completely exposed. Dipsosaurus possesses a row of slightly enku-ged 

 anterior auricular scales. Outgroup comparison indicates that the enlarged anterior 

 auriculars of Sauromalus are apomorphic. Basiliscines, Crotaphytus, Hoplocercus, 

 Morunasaurus, and some Enyalioides lack enlarged anterior auricular scales, while in 

 Gambelia and oplurines they are only slightly enlarged, roughly comparable to those of 



