Phylogenetic Systematics of I guanine Lizards 151 



2. Modal number of presacral vertebrae (Table 4): (0) 24; (1) 25. 



3. Modal number of premaxillary teeth (Table 3): (0) seven; (1) five. Although 

 Ctenosaura defensor is the only species with a mode of five premaxillary teeth (range 5-6), 

 the occurrence of five. premaxillary teeth in some specimens of C. clarki and C. 

 quinquecarinata, but in no other Ctenosaura, suggests that these three species form a 

 monophyletic group. 



4. Anterior orbital region (Fig. 10): (A) lacrimal contacts palatine behind lacrimal 

 foramen; (B) prefrontal contacts jugal behind lacrimal foramen. 



5. Cristae cranii (Fig. 12): (0) form smooth curve from frontal to prefrontal; (1) 

 frontal portions protrude anteriorly forming a step from frontal to prefrontal. 



6. Parietal roof: (0) remains deeply notched posteriorly throughout ontogeny, so that 

 the braincase is broadly exposed in dorsal view; (1) extends posteriorly as a flat shelf 

 during postembryonic ontogeny, so that the braincase comes to be largely covered in dorsal 

 view. This character is partially correlated with character 1, body size. 



7. Ontogenetic convergence of lateral edges of parietal roof: (A) eventually meet 

 posteriorly and form a midsagittal crest, giving the parietal roof a Y-shaped outline; (B) fail 

 to meet, or meet but fail to form a midsagittal crest, giving the parietal roof a trapezoidal or 

 triangular outline. This character is partially correlated with character 1, body size. 



8-9. Crowns of posterior marginal teeth: (AO) with a maximum of four cusps; (BO) 

 with a maximum of five or more cusps; (Al) with a maximum of three cusps. 



10. Pendulous dewlap: (0) absent; (1) present but small; (2) present and large. 



11. Parietal eye: (0) conspicuous externally; (1) external signs inconspicuous or 

 absent. This character may also be manifested in a reduction in the parietal foramen in C. 

 defensor, but my osteological sample of this taxon is small (N=l). 



12. Dorsal crest scales I: (0) conform in color and pattern to adjacent body scales; 

 adjacent crest scales similar in size; (1) unicolored and differing from body color; large, 

 flap-like crest scales separated by one or more smaller scales. 



13. Dorsal crest scales II: (0) high-keeled, large, and conspicuous, at least in neck 

 region; (1) low-keeled to flat, inconspicuous throughout length of crest. 



14. Middorsal scale row: (0) continuous from neck onto tail, or narrowly interrupted 

 in sacral region; (1) broadly discontinuous in lumbosacral region. 



15. Scales of anterodorsal surface of leg: (0) not enlarged or spinous; (1) enlarged and 

 spinous on shank but not on thigh; (2) enlarged and spinous on both shank and thigh. An 

 additional state could be recognized, since C. clarki and C. quinquecarinata have large 

 anterodorsal thigh scales compared to those of most other Ctenosaura, but these scales are 

 not as large as in C. defensor, and they are not spinous. 



16. Subdigital scales at the base of pedal digit 111: (0) with relatively small anterior 

 keels or with moderately large anterior keels that are separate from those of adjacent scales; 

 (1) with relatively large anterior keels fused at their bases to form a comb. 



17. Tail: (0) strongly spinose proximally, but not distally, and always longer than 

 body (snout- vent length/total length = 0.27-0.45), more than 30 caudal vertebrae; (1) tail 



