10 University of California Publications in Zoology 



widespread within Iguanidae and found in several other lizard families as well (Paull et al, 

 1976). Only Iguana iguana has been reported to differ from this seemingly primitive 

 condition in that this species supposedly lacks one pair of microchromosomes (Cohen et 

 al., 1967), but even this finding was contradicted in another study (Gorman et al., 1967; 

 Gorman, 1973). 



Iguanine relationships have only been studied superficially with relatively new and 

 increasingly popular biochemical techniques. Gorman et al. (1971) presented evidence for 

 close relationship among iguanines based on immunological studies of lactic 

 dehydrogenases and serum albumins in turtles and various diapsids. Higgins and Rand 

 (1974, 1975) showed that the serum proteins and hemoglobins of Amblyrhynchus and 

 Conolophus were more similar to each other than to those of Iguana. Unfortunately, other 

 iguanines were not examined. Wyles and Sarich (1983) performed immunological 

 comparisons of the serum albumins of 10 species of iguanines including representatives of 

 all eight genera. However, antisera were prepared to the albumins of only four of the 

 species, and comparisons with all others are given only for the antisera to the albumins of 

 Amblyrhynchus and Conolophus. Because of the incompleteness of the data, only very 

 general phylogenetic inferences can be drawn from them. 



The unique colon of iguanines was studied by Iverson (1980, 1982), who reported that 

 the iguanine colon differed from that of all other iguanids and most other lizards in the 

 possession of transverse valves or folds. However, Iverson (1980) felt that the variation in 

 these structures within iguanines was of httle value for inferring phylogenetic relationships. 



Peterson (1984) has recently surveyed the scale surface microstructure of iguanids. 

 Although some intergeneric variation in the morphology of the scale surface is known to 

 occur in iguanines, representatives of only three iguanine genera {Iguana, Dipsosaurus, and 

 Sauromalus) have been studied at this time. 



One final hypothesis about iguanine relationships deserves mention. At the prompting 

 of a colleague (Ernest Williams) some twenty-five years ago, Richard Etheridge drew up a 

 phylogenetic diagram depicting his views on the interrelationships among the iguanid 

 genera. The character basis for this diagram was not specified, and Etheridge (pers. 

 comm., 1981) informs me that the relationships shown among the iguanine genera were 

 strongly influenced by his knowledge about the geographic distributions of these animals. 

 Although he never intended the diagram to be published, it has been published in modified 

 form (Paull et al., 1976; Peterson, 1984), and has also appeared in several graduate theses. 

 I reproduce the original diagram here (Fig. 4), noting that its creator does not grant the 

 hypothesis the conviction seemingly implied by a branching diagram. 



GOALS OF THIS STUDY 



A detailed study aimed at revealing the pattern of phylogenetic relationships among the 

 various iguanine lizards is sorely needed. It would provide invaluable information for the 

 many people studying other aspects of iguanine biology, particularly in an evolutionary 

 context. I have attempted such a study here with the following as my goals: (1) to provide 



