170 University of California Publications in Zoology 



2. Second ceratobranchials of hyoid apparatus much longer than first ceratobranchials 

 (52-53-C). This character also occurs in Brachylophus, in which it is interpreted as 

 convergent. Within Iguana it occurs only in /. iguana and appears to be a synapomorphy 

 of that taxon. 



3. Caudal autotomy septa absent (60-B). This character occurs also in 

 Amblyrhynchina and in Brachylophus, in which it is interpreted as two separate instances 

 of convergence. Within Iguana it occurs only in /. delicatissima and appears to be a 

 synapomorphy of that taxon. 



Fossil record: Fossils referred to Iguana have been reported from Antigua (Wing et al., 

 1968), Barbados (Swinton, 1937; Ray, 1964), Martinique (Hoffstetter, 1946), and 

 Montserrat (Steadman et al., 1984) in the West Indies; Ecuador (Hoffstetter, 1970); and 

 southern California (Norell, 1983). The oldest of these are the Pliocene specimens from 

 southern California. However, since Norell (1983) considers these to be outside of the 

 clade consisting of /. iguana and /. delicatissima, they are not Iguana according to my 

 definition of this taxon, although they are its closest relatives. All other fossils referred to 

 Iguana are either Upper Pleistocene or Holocene in age. 



Comments: I consider the monophyly of Iguana to be reasonably well supported. 

 Nevertheless, three of the derived characters employed in this study occur in some Iguana 

 as well as in Qither Brachylophus (character 52-53-C), Amblyrhynchina (8-B), or both of 

 these taxa (60-B). The reason that I have interpreted these characters as convergent is 

 acceptance of the monophyly not only of Iguana but also of Iguanina and Iguanini, based 

 on other characters. 



Within Iguana, the two currently recognized species both appear to be monophyletic; 

 therefore, neither can be considered to be ancestral to the other. Monophyly of I. iguana is 

 supported by the extreme width of the parabasisphenoid, the enlarged subtympanic scale 

 (Dunn, 1934; Lazell, 1973), and the elongated second ceratobranchials. Monophyly of I. 

 delicatissima is supported by the short frontal bone, absence of autotomy septa in the 

 caudal vertebrae, enlarged bony extemal nares, and possibly the failure of the septomaxillae 

 to reach the roof of the nasal capsule. The possibility that Iguana is a subgroup of of 

 Cyclura is discussed in the comments on the latter taxon, below. 



Cyc/wra Harlan 1824 



Type species (subsequent designation by Fitzinger 1843): Cyclura carinata Harlan 

 1824. 



Etymology: (Greek) Kylclos, circle, -i- oura, tail, referring to the verticils of enlarged, 

 spinous scales on the tails of most species. 



