Morphological variation and geographical distribution in the South African lizards Typhlosaurus caecus (Cuvier 1817) and Typhlosaurus vermis Boulenger 1887 (Scincidae: Acontinae)

Abstract

The most recent evaluation of morphological variation in Typhlosaurus caecus was based on only six specimens, including one from Port Nolloth here referred to T. vermis. We report on morphological variation in 25 T. caecus and 33 T. vermis from several localities within their known ranges. The two species are allopatric and distinguishable on the basis of differences in head shield arrangement, numbers of scale rows round body, tail length/total length ratios, snout-vent length/body diameter ratios, numbers of subcaudals, and the position of the eye relative to the proximal end of the longitudinal groove in the rostral. All known locality records for the two species, including several new records, are documented and mapped. Typhlosaurus caecus is restricted to the coastal regions of the Western Cape province, while T. vermis occurs in the coastal regions of Namaqualand district, Northern Cape province. Although we confirm the identification of a T. vermis collected about 400 km to the east of the nearest other record for the species, further collecting is needed to confirm this locality.