Urosaurus bicarinatus Duméril

Castiglia, Riccardo, Annesi, Flavia, Bezerra, Alexandra M. R., García, Andrés & Flores-Villela, Oscar, 2010, Cytotaxonomy and DNA taxonomy of lizards (Squamata, Sauria) from a tropical dry forest in the Chamela-Cuixmala Biosphere Reserve on the coast of Jalisco, Mexico, Zootaxa 2508, pp. 1-29 : 16

Urosaurus bicarinatus Duméril (Tropical tree lizard)

Specimens analysed: one male from Chamela (CEAC19), one specimen from Rio Grande, Oaxaca (MZFC 12046), one specimen from Epatlan, Puebla (MZFC 6863).

Distribution: Mexican endemic. Pacific coast of Mexico, from Sonora to Chiapas.

Subspecies: U. b. bicarinatus , distributed from Michoacán to central Guerrero, and in the Río Balsas basin up to Morelos and southern Puebla; U. b. anonymorphus, found in east Guerrero, Oaxaca, and possibly western Chiapas; U. b. nelsoni, localized in northern Oaxaca; U. b. tuberculatus, distributed in Southern Sonora southward to Jalisco and Colima with isolated populations in Sinaloa; U. b. spinosus, from southwestern Chiapas. However, Wiens (1993) did not find morphological differences among the subspecies.

Karyotype: Unfortunately, we did not obtained good metaphases from this species.

DNA taxonomy: There is no sequence deposited in GenBank for this species. The available rDNA 16S sequences in GenBank are for U. ornatus , U. nigricaudus , U. microscutatus , and U. graciosus ( Reeder 1995) . We aligned these sequences with the sequence of U. bicarinatus from Chamela belonging to U. b. tuberculatus and with sequences from two additional individuals (Rio Grande, Oaxaca and Epatlan, Puebla) possibly belonging to U. b. nelsoni and performed a phylogenetic analysis using Sceloporus utiformis as the outgroup. The obtained tree is shown in Figure 8 . Interestingly, the phylogenetic relationships among species are different from those identified using morphological characters by Wiens (1993) and are congruent with Reeder’s (1995) results. Molecular analysis shows that U. bicarinatus has an external position with respect to the other species, which form a monophyletic group (supported only by NJ, 62%). Moreover in our tree U. ornatus is clearly the sister species of U. graciosus (supported by 87–99%). Conversely, phylogenetic relationships based on morphological characters show that U. graciosus was external to U. bicarinatus , U. nigricaudus , U. ornatus and U. microscutatus ( Wiens 1993) . The topology obtained with molecular data is congruent with the distribution of the species. U. bicarinatus is nested in the southern part of the range of the genus while the other species, which cluster together in the tree, are localized in the northern part.

The highest interspecific distance has been found between U. bicarinatus and the other species (8.4– 9.4%), while lower values have been found between the other species (3.5–7.7%). A low divergence value (1.8%) was found between sequences of the Rio Grande (Oaxaca) and Epatlan (Puebla) populations of U. bicarinatus . Greater distance was found between these two localities and the sequences from Chamela (4.3– 4.5%) belonging to a different subspecies. In the absence of additional data, it is very difficult to infer a conclusion regarding the taxonomic status of the Chamela population. These findings suggest that a complete intra and interspecific revision of the genus is needed using additional molecular markers.

Figures

FIGURE 8. Neighbour-Joining tree of 16 S rDNA haplotypes (455 bp) of Urosaurus species. Bootstrap values (%) obtained by the NJ, ML and MP are shown. The substitution model selected for ML was Tamura-Nei model (Tamura & Nei 1993) with rate variation among sites (+ G), and a gamma distribution shape parameter of 0.0855.