Karyological Comparison of Sphenops sepsoides, Chalcides chalcides, and C. ocellatus (Reptilia: Scincidae): Taxonomic Implications

Abstract

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Standard karyotype of Chalcides boulengeri (Anderson, 1896) (Reptilia: Scincidae) from Tunisia and Morocco

“…Like the results of Caputo et al (1993a), the present data thus evidence a strong karyological relatedness between the species previously attributed to the genus Sphenops and those of Chalcides. Indeed, the morphological traits used to determine the taxonomic status of Sphenops (see Pasteur and Bons, 1960) evolved in response to strong selective pressures (Caputo, 2004) and arose in several groups of sand-dwelling lizards by convergence (e.g., Luke, 1986), whereas karyological features, not being directly under selection, may be more appropriate to recognize evolutionary affinity, and in the present case strongly suggest a monophyletic origin of these scincid lizards.…”

“…This may indicate the absence of chromosome changes that could act as reproductive barriers between these populations, and that they constitute a single reproductive community (see Caputo and Odierna, 1992, for similar considerations). The karyotype of C. boulengeri closely resembles those of C. sepsoides (Caputo et al, 1993a) and C. sphenopsiformis (Capriglione, 1987), from which it differs by two and three pericentric inversions, respectively. In particular, the 6 th chromosome pair is metacentric in boulengeri and subtelocentric in sepsoides and sphenopsiformis, whereas the 9 th pair is subtelocentric in boulengeri and metacentric in sepsoides and sphenopsiformis; the 10 th pair is subtelocentric in boulengeri and acrocentric in sphenopsiformis.…”

“…subgenus Sphenops Wagler 1830, previously considered a distinct genus, but recently included in Chalcides Laurenti, 1768 based on karyological and osteological data (see Caputo et al, 1993a, andCaputo, 2004; see also Mateo et al, 1995). It inhabits sandy regions around the north African Sahara desert from Morocco to Libya (Mellado and Dakki, 1988;Le Berre, 1989;Bons and Geniez, 1996;Schleich et al, 1996).…”

“…It is a diurnal species, but becomes nocturnal in the hottest months of the summer. Two species of the subgenus Sphenops have been karyotyped so far: C. sphenopsiformis (Duméril) (Capriglione, 1987) and C. sepsoides (Audouin) (Caputo et al, 1993a), both sharing a karyotype of 28 chromosomes and differing only by a pericentric inversion involving the 10 th pair. We describe the standard karyotype of C. boulengeri The karyotypes analysed come from three adult females from Morocco (Hamada du Dra, environs of Zagora) and from six adults (3 males and 3 females) from south western Tunisia (Gouifla steppe, environs of Gafsa).…”

The cranial osteology and dentition in the scincid lizards of the genusChalcides(Reptilia, Scincidae)

“…They live about 5 cm below the surface and move through sinuous body undulations and oscillations of the head (Schleich et al, 1996). Caputo et al (1993), based on the comparison of the chromosome complements of Chalcides chalcides, C. ocellatus, Sphenops sepsoides and S. sphenop-siformis, suggested that the species attributed to the genera Chalcides and Sphenops constitute a monophyletic group, with the species commonly ascribed to Sphenops being the result of speciation within the genus Chalcides triggered by specific ecological conditions (adaptation to desert environments).…”