Cnemidophorus is a genus of lizards in the family Teiidae. Species in the genus Cnemidophorus are commonly referred to as whiptail lizards or racerunners. The genus is native to South America, Central America, and the West Indies.

Taxonomy: Reeder et al. (2002) re-examined the nomenclature for the genus Cnemidophorus (sensu lato) and split it into the two genera Aspidoscelis and Cnemidophorus (sensu stricto). A further split by Harvey et al. (2012) added the genera Ameivula and Contomastix.

Etymology: The name Cnemidophorus literally means "greave-wearing", from the Ancient Greek ´ (combining form of ´, "greave", a leg armor) and ("bearer").

Reproduction: In some of the Cnemidophorus species, there are no males, and they reproduce through parthenogenesis. This is well known in bees and aphids, but is very rare in vertebrates. Those species without males are now known to originate through hybridization, or interspecific breeding. Occasionally, a mating between a female of one species and a male of another produces a parthenogen, a female that is able to produce viable eggs that are genetically identical to her own cells. The lizards that hatch from these eggs are thus also parthenogens that can again produce identical eggs, resulting in an asexual, clonal population. Parthenogenetic species resulting from a single hybridization are diploid (that is, they have two sets of chromosomes just as sexual species do), but sometimes these females mate with other males, producing offspring which are triploid (that is, they have three sets of chromosomes, or 50% more than equivalent sexual species; see polyploidy). Over 30% of the genus Cnemidophorus are parthenogenic.

Species: The genus Cnemidophorus (sensu stricto) contains the following species which are recognized as being valid.

• Cnemidophorus arenivagus
• Cnemidophorus arubensis – Aruba whiptail
• Cnemidophorus cryptus – cryptic racerunner
• Cnemidophorus duellmani
• Cnemidophorus espeuti
• Cnemidophorus flavissimus
• Cnemidophorus gaigei – Gaige´s rainbow lizard
• Cnemidophorus gramivagus
• Cnemidophorus lemniscatus – rainbow whiptail
• Cnemidophorus leucopsammus
• Cnemidophorus murinus – Laurent´s whiptail
• Cnemidophorus nigricolor
• Cnemidophorus pseudolemniscatus – Cole´s racerunner
• Cnemidophorus rostralis
• Cnemidophorus ruatanus
• Cnemidophorus ruthveni
• Cnemidophorus senectus
• Cnemidophorus splendidus – blue rainbow lizard
• Cnemidophorus vanzoi – Saint Lucia whiptail, Vanzo´s whiptail

Nota bene: A binomial authority in parentheses indicates that the species was originally described in a genus other than Cnemidophorus.