Mexican spiny-tailed iguana

Description

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. C. pectinata has distinctive keeled scales on its long tail, to which its common name refers. It is one of the larger members of the genus Ctenosaura, capable of growing to 1.3 m (4.3 feet) in total length (including tail), with females being slightly smaller than males at 1.0 m (3.3 ft). It is usually brown or grey-brown in coloration dorsally, with a yellowish ventral surface. It has a crest of long spines which extend down the center of its back. Hatchlings are often a bright green color with no body pattern, and darken as they age. Ctenosaura pectinata often (but not always) has an irregular piebald pattern on the head or dorsal areas. Although the tail may be banded with light and dark crossbands, C. pectinata typically lacks a clear or well developed crossband pattern on the body, which is often present in the similar appearing and closely related species Ctenosaura similis and Ctenosaura acanthura. Ctenosaura pectinata varies from gray to a brownish-black, with some males exhibiting yellowish colors, and females orange color, on the lateral sides of the body.