Ctenosaura pectinata is a species of moderately large lizard in the family Iguanidae. The species is native to western Mexico. The standardized English name is the western spiny-tailed iguana. However, an earlier edition of standardized names applied the name Mexican spinytailed iguana to Ctenosaura pectinata. Confoundedly the name Mexican spiny-tailed iguana was applied to Ctenosaura acanthura which was referred to as the northeastern spinytailed iguana in the earlier edition of standardized names. It has also been called simply the spiny-tailed iguana, black spiny-tailed iguana, Guerreran spiny-tailed Iguana, broad-ringed spiny-tailed iguana among other common names. The taxonomic status, relationships, and validity of a number of spiny-tailed iguana, particularly Ctenosaura acanthura, C. pectinata, and C. similis have an extensive history of confusion in both scientific and popular literature. The status and relationship of Ctenosaura acanthura and C. pectinata remains unstable (as of 2021) with some limited molecular evidence suggesting Ctenosaura acanthura is a synonym (the same species) of C. pectinata, while others recognize the two as allopathic, morphologically distinct species. The common names Mexican spiny-tailed iguana and black spiny-tailed iguana (among many other common names) have been loosely and informally applied to all three species at various times. Geographic range In Mexico it is found from central Sinaloa to southern Chiapas. It has also been introduced to the United States in the very southern tip of the state of Texas and in the state of Florida. Taxonomy C. pectinata was first described by German zoologist Arend Friedrich August Wiegmann in 1834. The generic name, Ctenosaura, is derived from two Greek words: ctenos (Κτενός), meaning "comb" (referring to the comblike spines on the lizard's back and tail), and saura (σαύρα), meaning "lizard". Its specific name is the Latin word pectinata meaning "combed", also referring to the comblike spines on the lizard's back. The genus it belongs to represents the most diverse group of iguanas with 15 currently recognized species. These species inhabit lowland (below 1200m elevation) dry forests on both coasts of Mexico and Central America. All species of Ctenosaura fall within one of seven clades. Distributions of these clades fall geographically within well established areas. Closely related species show allopatry whereas species from divergent clades show sympatry. Phylogenic study shows this species to be most closely related to C. acanthura, the Northeastern spinytail iguana. Additional mitochondrial DNA research is being performed to determine whether additional subspecies may exist. Because of the different