Burrowing performance and the role of limb reduction inLerista (Scincidae, Lacertilia)

Abstract

Size parameters of the fossorial lizardsLerista elegans, L. lineopunctulata andL. praepedita were measured and burrowing performance was observed. InL. elegans all four limbs were fully developed (relative hindlimb length, PHL, is 29.2 % of snout-vent length, SVL) with four toes while inL. lineopunctulata frontlimbs were almost completely reduced and hindlimbs (PHL is 9.0 % of SVL) had not more than one toe and inL. praepedita even the hindlimbs were reduced to short stumps (PHL is 2.1 % of SVL). The smallest SVL and total length (TL) was found inL. elegans (mass 0.597 g, SVL 37.0 mm, TL 80.9 mm, body width, BW, 3.921 mm).L. praepedita did not differ too much fromL. elegans in mass, but had a greater SVL and TL and a smaller BW (mass 0.502 g, SVL 52.8 mm, TL 93.4 mm, BW 2.804 mm).L. lineopunctulata had the biggest mass, SVL and TL (mass 4.113 g, SVL 84.1 mm, TL 142.9 mm, BW 6.367 mm). According to this dataL. elegans is morphologically less adapted to fossoriality than the other two species, what corresponds to field observations of behaviour. The technique of burrowing performance, the time needed and the use of the hindlimbs were compared. During trialsL. elegans showed the least motivation to burrow, whileL. lineopunctulata andL. praepedita burrowed always and almost immediately. Both species also burrowed with higher speed thanL. elegans. L. praepedita burrowed with undulating movements, the limbs were never used, whileL. elegans pushed the body inside the substrate with its limbs and started undulating only after the hindlimbs were burrowed. Burrowing performance ofL. lineopunctulata showed a combination of both techniques. InL. elegans, the time needed for burrowing and the use of the hindlimbs increased with size and mass. InL. lineopunctulata andL. praepedita head size was the most important factor.