Plestiodon Duméril and Bibron

The genus Eumeces has been recently split into four genera, namely Pariocela, Eumeces, Eurylepis, and Mesoscincus (Schmitz et al. 2004) . Because of priority reasons, the name Plestiodon has been adopted instead of Pariocela for those American species formerly referred to as Eumeces, except for those placed in Mesoscincus (Smith 2005) . The differences among the groups were based in part on analyses of chromosomes numbers. A large number of studies showed that all species of the American Plestiodon have 2n = 26 chromosomes (Deweese & Wright 1970; Wu 1983; Capriglione 1987; Guo & Dong, 1988; Kato et al. 1998), while all the African species of the genus Eumeces are unique in having a constant 2n = 32 chromosomes (Gorman 1973; Kupriyanova 1973; De Smet 1981; Kupriyanova 1986; Eremchenko et al. 1992; Caputo et al. 1993, 1994; Hassan 1996). The Eurylepis taeniolatus group can be also differentiated from other groups by uniquely having 2n = 28 chromosomes (Ivanov & Bogdanov 1975; Kupriyanova 1986; Eremchenko et al. 1992).

Molecular phylogenetic analysis by Schmitz et al. (2004), which included American species, identified four species groups in Plestiodon: a group comprised of P. anthracinus, P. egregius and, surprisingly, Neoseps reynoldsi; a “ laticeps ” species-group including laticeps, inexpectatus, fasciatus, obsoletus, septentrionalis and obstusirostris; a “ skiltonianus ” species-group with skiltonianus, gilberti and rubricaudatus; a clade composed of the two Mexican species P. brevirostris and P. l y n x e.

Following the recent systematic revision of the genus, Plestiodon “ sensu stricto ” contains 41 species. Ten species have been karyotyped and all showed 2n = 26 (12 macro- and 14 microchromosomes) (Caputo et al. 1994). The karyotypes differ in the morphology of microchromosomes, however, this can be partly due to the interpretation of smaller chromosomes by different authors.