168 University of California Publications in Zoology 



Although there are fewer characters supporting a sister-group relationship between 

 Cyclura and Iguana than there are for some of the other relationships proposed in this 

 paper, the monophyly of Iguanina is reasonably well supported. This sister group of 

 Iguanina is not obvious from the results of the present study, but the best candidates are 

 Ctenosaura and Sauromalus (or perhaps a group composed of both these taxa). Only 

 Sauromalus shares a derived character with Iguanina that is not variable within either of 

 these taxa, increased cuspation of the posterior marginal teeth (46-B,-C). The distribution 

 of other derived characters among taxa within Iguanini requires either that one or more of 

 the basic taxa are not monophyletic or that some kind of homoplasy is involved. 



Iguana Laurenti 1768 



Type species (by tautonomy): Lacerta iguana Linnaeus 1758. 



Etymology: (Spanish) Iguana, a modification of the name given to these animals by 

 West Indian natives. 



Definition: The most recent common ancestor oil guana delicatissima and /. iguana and 

 all of its descendants. 



Distribution: Lowlands of the American mainland from Sinaloa and Veracruz, Mexico, 

 southward through Central America and northern South America to southern Brazil and 

 Paraguay; in the Caribbean northward through the Lesser Antilles to the Virgin Islands 

 (Fig. 58). 



Diagnosis: Members of this taxon can be distinguished from other iguanines by the 

 following synapomorphies: 



1. Large ventral process of squamosal (18- A) abuts against dorsal edge of tympanic 

 crest of quadrate. Because the reduction of the ventral process of the squamosal is an 

 iguanine synapomorphy, its reelaboration in Iguana is a character reversal. 



2. Cristae ventrolaterales of parabasisphenoid barely constricted behind basipterygoid 

 processes (28-C). This character also occurs in some Cyclura and, although I have 

 interpreted this as convergence, a wide parabasisphenoid may be a synapomorphy of a 

 more inclusive group. 



3. Crowns of posterior marginal teeth serrate, with numerous small accessory cusps 

 (46-D). 



4. Entire pterygoid tooth patch doubles ontogenetically (49-C). 



5. Posterolateral processes of pleurapophyses of second sacral vertebra absent (57-B). 

 This character occurs also in Ctenosaura and in most Cyclura, and may be a synapomorphy 

 of a more inclusive group. 



