The Mexican spiny tail iguana is mainly herbivorous and feed on leaves and flowers. However, juveniles of this species consume insects such as spiders, ants, and beetles. Furthermore, the diet of immature iguanas overlaps with the adults. Durtsche (2000) studied the ontogenetic shift that occurs in this species between the juvenile and immature size classes. Adults were observed to rarely eat insects and eat mostly plants. It was observed that these iguanas mainly ate plants from the family Fabacea that constantly produce flowers throughout the year for their consumption. Species of this plant family are legumes and contain a large source of nitrogen for protein. It was suggested that juveniles eat insects to have enough nutrients and protein for the required growth rate to reach adults size. The ontogenetic shift in diet does not reflect a change in the morphology of their digestive tract because there were no morphological differences in digestive tract organ lengths and volumes among age groups. However, juveniles do not have the digestive ability and lack nematodes and microbe colonies to ferment plant fiber. Retaining an herbivore gut structure throughout life may help juveniles grow by allowing them to eat a variety of foods.
The Mexican spiny tail iguana is named after their distinctive keeled scales on their long tails. It has an elongate and depressed head with a pronounced transverse gular fold (Oelrich 1956). They have small and fine scales. To distinguish this species from the black spiny tail iguana (Ctenosaura similis), the Mexican spiny tail iguana have 0-20 scales separating rows of intercalary scales between whorls of enlarged caudal scales near the base of the tail (Townsend et al 2003). This species is a moderate sized lizard but is one of the largest in the Ctenosaura genus. Adult iguanas can grow more than 1 meter in length. Adults of this species are either black or gray in color with yellow spots scattered over the body and lack dark dorsal crossbands. Juveniles are bright green and gray with dark crossbands. Females of this species are smaller than the males and do not possess the elongate dorsal spines that are present on the males.
The skull of this species is comprised of cartilage, fibrous membranes, and bones in different degrees of ossification (Oelrich 1956). The non-specialized condition of this species is reflected in the snout, orbits, and temporal fossae of the skull, which are all of moderate size and are about equal in length. Additionally, the maxillary segment is elevated and depressed on the occipital segment and makes the skull kinetic. This characteristic helps lizards chew. These lizards also have a nasal salt gland to excrete hypertonic concentrations of salts (Templeton 1967).
The native range of this species is from central Sinaloa to southern Chiapas in Mexico. Central Sinaloa consists of valleys with a temperate to hot climate. The southern part of Chiapas is a coastal plain next to the Pacific Ocean. The climate of this area is humid and the temperature ranges from 32 degrees F to 104 degrees F. They are also an introduced species to the United States, and have established populations in southern Texas near Brownsville and in Miami, Florida.
The Mexican spiny tail iguana inhabit elevations below 1,500m and has adapted to landscapes that can be described with black volcanic rocks and black soil with sparse vegetation. The dark rocks and soil allow this species to camouflage into the environment. Villages and gardens provide sufficient shelter and food and water. They also prefer open areas with objects where they can hide in such as holes, crevices, wood, and rock walls (Conant and Collins 1998). They can also be found in rocky hillsides and in trees (Oelrich 1956).
Unlike other members of the Ctenosaur genus and other reptiles such as anoles and geckos, Mexican spiny tail iguanas are rather social, but can also be timid (Faria et al 2010). They like to aggregate where the ecological conditions favor lizard communities such as villages and gardens. Evans (1951) revealed that a male dominance hierarchy exists in this species and it has evolved from territorial behavior. Males will select and defend a territory that possesses shelter, food and water supplies, and a lookout point. It was observed that dominant males (referred to as “tyrants”) would patrol their territory by observing and challenging other males. Challenging involves strutting and head nodding with an open mouth, distended throat, and flattened sides.
Evans (1951) briefly described their courtship behavior. It was observed that both sexes participated in the courtship ritual rather than the female being passive. The male courtship display is similar to the challenging behavior towards other males. This includes head nodding and side flattened strutting. The female would then react positively to the display by approaching the male and nodding. Females move from site to site to find a male with suitable territory to nest. In this species, females were found to be genetically monogamous within a breeding season and multiple paternity occurs at a low frequency (Faria et al 2010)
Ayala-Guerrero and Huitron-Resendiz (1991) studied the sleep patterns of Mexican spiny tail iguanas. Their results showed that this species displayed four vigilance states (active wakefulness, quiet wakefulness, quiet sleep, and active sleep) throughout their nyctohemeral cycle (also known as circadian cycle). In the active wakefulness stage, their eyes are open and their bodies are fully lifted by standing on their four legs. They are also seen eating during this stage. During the quiet wakefulness stage, their eyes are still open, but they are less active than in active wakefulness. These iguanas spend most of their nyctohemeral cycle in the quiet sleep stage in which they are completely relaxed and motionless. Their eyes are closed and their bodies are fully extended along the ground while their limbs extend close to their body. They spend a short period of time in the active sleep stage. In this stage, their eyes are also closed, but sometimes open and coincide with their movements. Although they are lying down in this stage they are not entirely motionless. For instance, their eyes, head, jaw, tail, and legs move. Furthermore, their anterior leg movement resembles a swimming motion.
In addition to their social behavior, Mexican spiny tail iguanas are excellent climbers and are fast moving. Furthermore, they will use their tails to deter predators. They will spend most of their time motionless to blend into the environment.
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.[4]: 58–59 p. However, an earlier edition of standardized names applied the name Mexican spinytailed iguana to Ctenosaura pectinata.[5]: 46 p. Confoundedly the name Mexican spiny-tailed iguana was applied to Ctenosaura acanthura[4]: 58–59 p. which was referred to as the northeastern spinytailed iguana in the earlier edition of standardized names.[5]: 45–46 p. It has also been called simply the spiny-tailed iguana,[6]: 506 p. [7]: 216 p. black spiny-tailed iguana,[8]: 265 p. Guerreran spiny-tailed Iguana,[1] broad-ringed spiny-tailed iguana[9]: 144 p. 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.[10][11][12][13] 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.
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.
C. pectinata was first described by German zoologist Arend Friedrich August Wiegmann in 1834.[14] 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".[15] Its specific name is the Latin word pectinata meaning "combed", also referring to the comblike spines on the lizard's back.[16] The genus it belongs to represents the most diverse group of iguanas with 15 currently recognized species.[17] These species inhabit lowland (below 1200m elevation) dry forests on both coasts of Mexico and Central America.[17] All species of Ctenosaura fall within one of seven clades.[17] Distributions of these clades fall geographically within well established areas.[17] Closely related species show allopatry whereas species from divergent clades show sympatry.[17] Phylogenic study shows this species to be most closely related to C. acanthura, the Northeastern spinytail iguana.[18] Additional mitochondrial DNA research is being performed to determine whether additional subspecies may exist.[19] Because of the different human cultures throughout this species distribution, the clades are being evaluated for their impact from humans.[19] For example, these iguanas are not eaten in their northern ranges by humans as they are in the southern ranges, but the hatchlings in the southern ranges have a better survival rate due to better environmental conditions.
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.[15] It has a crest of long spines which extend down the center of its back.[15] Hatchlings are often a bright green color with no body pattern, and darken as they age.[20]
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.[21]: 144 p. 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.[22]: 143 p. The young are bright green and unmarked except for black tail bands, present also on adults.[23]: 123 p.
C. pectinata is native to Western Mexico from Sinaloa to Oaxaca.[15][16]
This iguana has been introduced to Brownsville, Texas and South Florida and reproduces in the wild in several feral populations.[24] On the south-eastern Florida coast, these iguanas have been found on Key Biscayne, Hialeah, and in Broward County. On the south-western Florida coast, it has been reported on Gasparilla Island.[25] It is currently estimated as of December 2007 that there are 12,000 iguanas on this island, descended from a trio of pet lizards released by a resident in the 1970s.[26]
They are regarded as a "nuisance animal" on Gasparilla island because the iguanas eat ornamental flowers and shrubs and prey on nesting birds and sea turtle eggs.[26] They have been known to chew through electrical and telephone cables.[26] They may also carry salmonella and their appearance has been known to scare timid residents.[26] As the iguanas like to burrow in the sand it is feared that their tunnels could cause dunes and even seawalls to collapse and deprive the island of crucial protection from landfalling hurricanes.[26]
C. pectinata is a social lizard, which has adapted to living in groups as opposed to other species of Ctenosaura which tend to be solitary animals.[27] These iguanas are excellent climbers, and prefer a rocky habitat with plenty of crevices to hide in, rocks to bask on, and nearby trees to climb.[15][24] They are diurnal and fast moving, employing their speed to escape predators but will lash with their tails and bite if cornered.[15] They are often found dwelling near or in towns in their native Mexico and where they have been introduced elsewhere.[24]
Juveniles consume a diet consisting mostly of insects. However, adults are primarily herbivorous, eating a variety of flowers, leaves, stems, and fruit, but they will opportunistically eat small animals, eggs, and arthropods.[24]
Mating of C. pectinata occurs in the spring. Males show dominance and interest by head bobbing, eventually chasing the female until he can catch her and subdue her.[15] Within eight to ten weeks, the female will dig a nest and lay clutches of up to 50 eggs in a burrow of loose soil.[15][20] These eggs hatch in 90 days with the bright green babies digging their way out of the sand.[15] The bright green hatchlings first appear around July and are abundant in August.[23]: 123 p.
C. pectinata is used as a traditional food source in its native Mexico.[28] This species is listed as "Least Concern" by the IUCN Redlist, but the species is listed on the Mexican Red List NOM-059-2001 as threatened and it is currently illegal to hunt them in Mexico.[19] This protection does not apply to areas in North America where they have been introduced, however.
Although hunting, trapping, and killing of these iguanas is illegal throughout Mexico; the Balsas depression along the borders of the states Michoacán and Guerrero is one of the largest illegal hunting and trading areas.[28] The remoteness of the areas and lack of enforcement of the laws is seen as the main reason.[28] A study is being conducted by the Instituto de Biologia, UNAM, to solve the over-exploitation problem and to determine if the iguanas can be successfully farmed as a food source similar to the Green Iguana and the closely related Ctenosaura similis.[19]
Male showing yellow coloring on the lateral sides of the body, Rio Tamazula, Parque Las Riberas, Culiacan, Sinaloa, Mexico (23 March 2010)
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A female from Puerto Escondido, Oaxaca, Mexico (23 December 2016)
A female from the Huatulco Coast area of Oaxaca, Mexico (29 December 2010)
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A female photographed in the Huatulco Coast area in Oaxaca, Mexico (2013)
Ventral view of a Ctenosaura pectinata from the vicinity of Acapulco, Guerrero, Mexico (16 September 2013)
Juveniles are a bright green color as this one from the Bosque de la Primavera region of Jalisco, Mexico (2013)
Ctenosaura pectinata from the area of Playa Escobilla, Oaxaca, Mexico (13 September 2010)
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.: 58–59 p. However, an earlier edition of standardized names applied the name Mexican spinytailed iguana to Ctenosaura pectinata.: 46 p. Confoundedly the name Mexican spiny-tailed iguana was applied to Ctenosaura acanthura: 58–59 p. which was referred to as the northeastern spinytailed iguana in the earlier edition of standardized names.: 45–46 p. It has also been called simply the spiny-tailed iguana,: 506 p. : 216 p. black spiny-tailed iguana,: 265 p. Guerreran spiny-tailed Iguana, broad-ringed spiny-tailed iguana: 144 p. 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.
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