Lepidophyma flavimaculatum Dumeril , 1851

Castiglia, Riccardo, Flores-Villela, Oscar Alberto, Bezerra, Alexandra M. R., Gornung, Ekaterina, Annesi, Flavia, Munoz-Alonso, Luis Antonio & Solano, Emanuela, 2020, Detection of cryptic diversity in lizards (Squamata) from two Biosphere Reserves in Mesoamerica, Comparative Cytogenetics 14 (4), pp. 613-638 : 613

Lepidophyma flavimaculatum Dumeril, 1851

Note.

Bezy and Camarillo (2002) did not recognize subspecies, although they admitted that populations of this taxon form a complex, therefore representing more than one taxon. It is the only vertebrate species with unisexual parthenogenetic populations that are of non-hybrid origin ( Sinclair et al. 2010).

Distribution.

Found on the Gulf of Mexico coast from Veracruz and Oaxaca, crossing the base of the Yucatan peninsula, through Central America to Panama.

Samples.

RCMX207 (female*), RCMX208 (male*), RCMX212 (female*), RCMX213 (male*), and RCMX232 (female*) from Montes Azules, Chiapas state, Mexico.

DNA taxonomy.

Our samples have been identified on a morphological basis as Lepidophyma flavimaculatum , a species already reported for Chiapas. We aligned our 309 bp MT-CYB sequences to the 14 haplotypes of the same species published in Sinclair et al. (2010) from Honduras, Nicaragua and Belize, as well as the unisexual populations from Costa Rica and Panama; L. reticulatum Taylor, 1955 and L. lipetzi Smith et Del Toro, 1977 were used as outgroups. The phylogenetic trees (Fig. 6A ) showed that our samples are sister to the L. flavimaculatum clade, but it forms a separate and well supported lineage (p.p. = 1) with 3.9% of genetic divergence. The TCS network (Fig. 6B ) confirms that the samples from Chiapas are differentiated from all the other populations of L. flavimaculatum by 8 substitutions, whereas the other haplotypes differ from each other by not more than 3 substitutions. The shallow distinction of the Chiapas population may reflect the phylogeographic structure of the species, in accordance with its distant geographical location. Moreover, Bezy (1989) found that Chiapas specimens are morphologically distinct from other southern Mexican samples. Therefore, additional comparative studies at the northern edge of the species range are needed.

Chromosomes.

Diploid chromosome complements vary from 2n = 24 to 2n = 40 in Xantusiidae ( Olmo and Signorino 2005). Within Xantusia Baird, 1859 the karyotypic formula is highly conserved with all studied species displaying 2n = 40, while the genus Lepidophyma is much more variable with diploid number ranging from 2n = 32 to 2n = 38 ( Olmo and Signorino 2005). There is no evidence of heteromorphic sex chromosomes within the family, but recently a ZZ/ZW sex chromosomes system was described in the X. henshawi Stejneger, 1893 ( Nielsen et al. 2020). In L. flavimaculatum unisexual parthenogenetic populations are known from Panama and southeastern Costa Rica, whereas northern populations are bisexual. All unisexual populations so far studied are diploid (2n = 38), except one mosaic individual (2n/3n) ( Bezy 1972). All individuals presently analysed (Fig. 7 ) showed 2n = 38 with 18 macrochromosomes and 20 microchromosomes, as previously reported by Bezy (1972).

Figures

Figure 6. Bayesian phylogenetic tree (A) and TCS network (B) of 16 S haplotypes belonging to Lepidophyma flavimaculatum. The colors refer to the geographic provenience of individuals. In bold, the new specimens from this study.

Figure 7. The karyotype of Lepidophyma flavimaculatum (2 n = 38, RCMX 208 male).