Phylogenetic Systematics of I guanine Lizards 1 45 



iguanines, Brachylophus also exhibits enlargement of the second and third postxiphisternal 

 inscriptional ribs, which may also unite to form continuous chevrons. 



10. Large dewlap present (88-E). The two species oi Brachylophus differ in that a 

 large dewlap is present in both sexes of B. vitiensis but only in male B.fasciatus 

 (Gibbons, 1981). The polarity of this character is uncertain. If presence of a large dewlap 

 is derived, then the phylogenetic relationships proposed here require that it has evolved 

 convergently in Iguana and in some species of Ctenosaura. 



In addition, the following derived character occurs in some Brachylophus: 

 Posterior marginal teeth with a fourth cusp (46-B). This character occurs in all other 

 iguanines except Amblyrhynchus and some Ctenosaura; it may thus be a synapomorphy of 

 a more inclusive group, perhaps of all iguanines. 



Fossil record: Bones thought to be remains of Brachylophus are known from 

 archaeological sites on Tongatapu and Lifuka in the Tonga Islands group (approximately 

 2000 years before present). If correcdy referred, these bones indicate that Brachylophus 

 once reached much larger sizes than they do today (Etheridge, pers. comm.; Pregill, pers. 

 comm.). 



Comments: Gibbons (1981) discusses the authorship oi Brachylophus, crediting the 

 name to Wagler (1830), since Cuvier (1829) had used the informal apellation les 

 Brachylophes. The relationships oi Brachylophus to Dipsosaurus and other iguanines are 

 discussed in the comments on Dipsosaurus, above. 



IguaniniBell 1825 



Type genus: Iguana Laurenti 1768. 



Etymology: Modification of Iguana, the name of its type genus. 



Definition: The most recent common ancestor of Ctenosaura, Sauromalus, 

 Amblyrhynchina, and Iguanina, and all of its descendants. 



Distribution: Southwestern United States southward through Mexico, Central America, 

 and northern South America to southern Brazil and Paraguay, the West Indies, and the 

 Galapagos Islands. 



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

 {Brachylophus and Dipsosaurus) by the following synapomorphies: 



1. Lateral process of palatine contacts jugal behind infraorbital foramen (23-B). This 

 character does not occur in some Sauromalus, where it is interpreted as a reversal. It does 

 occur in Brachylophus and may thus be a synapomorphy of a more inclusive group. 



