Coleonyx elegans Gray

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 : 10-11

Coleonyx elegans Gray (Yucatan Banded Gecko)

Specimens analysed: one female (CEAC8), two specimens from Petén, Guatemala (UTA R 50283, UTA R 50286).

Distribution: Mexico, Belize, Guatemala, and El Salvador.

Subspecies: C. e. elegans Gray distributed from central Veracruz, Mexico to northern Guatemala and Belize and on the Pacific coast from eastern Chiapas, Guatemala to western El Salvador; C. e. nemoralis Klauber is localized along the Pacific coast of Mexico from Nayarit to southeast Oaxaca.

Following Klauber (1945), the diagnostic characters distinguishing the two subspecies of the Yucatan Banded Gecko are a non-triangular mental and the upper prenasals in contact in C. elegans elegans ; the mental is usually triangular, the prenasals are usually not in contact, and there are fewer tubercular scales laterally in C. e. nemorali s. The studied specimen from Chamela is within the range of C. e. nemoralis, however, it represents intermediate morphological characters since the mental is clearly not triangular and since the upper prenasals are not in contact.

Karyotype: this is the first description of the karyotype for this species. It shows 2n = 31 and FN = 32 ( Fig. 4 ). The karyotype is composed of one single unpaired metacentric (the largest chromosome) and 30 acrocentric chromosomes. The metacentric chromosome clearly represents a Robertsonian fusion of two acrocentric chromosomes. Among the species studied, this karyotype is most similar to that described for C. variegatus , with a 2n=32 all-acrocentric karyotype, but differs considerably from C. switaki (2n = 24, FN = 26). Therefore, it is the first instance of chromosomal heteromorphism reported for Eublepharidae . Few cases of heteromorphism due to Robertsonian fusion or fission have been reported in Gekkonidae , e.g., in Gehyra australis and G. variegata ( King 1984) , in Gekko chinensis Lau et al. (1997) , in Phyllodactylus lanei (see below) and in Christinus marmoratus ( King & Rofe 1976) . Clearly, additional data will be necessary to understand if this chromosomal heteromorphism represents a sex chromosome system, hybridization between chromosomal cytotypes or an intra-population autosomal polymorphism.

DNA taxonomy: only one rDNA 16S sequence from C. elegans is present in GenBank ( Jonniaux & Kumazawa 2008) but the studied specimen belonged to a pet-shop (Yoshi Kumazawa, pers. comm.). For this reason we include two specimens from Petén ( Guatemala) belonging to the other subspecies, C. e. elegans . The sequence of the specimen from Chamela differs by 4.5% with respect to the other haplotypes that are, conversely, very similar. This level of divergence is high but lower relative to that found between different species ( C. variegatus vs C. brevis , 9.8%; C. mitratus vs C. elegans , 14–15.2%). In absence of additional data these results are in agreement with a subspecific status of the populations from Jalisco and Guatemala.

Figures

FIGURE 4. Karyotype of Coleonyx elegans, female (2 n = 31 and FN = 32). Note the single large metacentric (no. 1) that it is tentatively paired with two medium sized acrocentric chromosomes.