Sceloporus utiformis Cope (Cope's largescale spiny lizard)

Specimens analysed: three males (CEAC 12, CEAC13, CAEC14)

Distribution: Mexican endemic. It is distributed along the Pacific slope from southern Sinaloa to western Guerrero.

Subspecies: no subspecies have been described.

Karyotype and DNA taxonomy: the karyotype for this species has been described from two specimens, one male and one female, both from Jalisco in a locality (northwest of Puerto Los Mazos) about 70 Km from Chamela (Cole 1971). The diploid number was 2n = 34 and the male carried a heteromorphic pair of microchromomes that were not present in the female. This polymorphism has been interpreted as a XY sex chromosomal system (Cole 1971). The specimens analysed in this study show a karyotype identical to the one previously reported (Fig. 7). It is composed of 12 biarmed chromosomes and 22 microchromosomes. In these male individuals one of the microchromosomes is very small. Therefore we confirm the presence of a XY sex chromosome system in this species.

The rDNA 16S has been studied for a single specimen from Jalisco (Boca de Iguanas), which is near the locality for specimens in the present study (Wiens & Reeder 1997; Flores-Villela et al. 2000). The from Chamela differ by 3% from the previous studied sample, which is a low value of divergence consistent with an intraspecific divergence.