Taxonomy
The Rhinoceros Iguana is a species of lizard belonging to the genus Cyclura. The generic name (Cyclura) is derived from the Ancient Greek cyclos (κύκλος) meaning "circular" and ourá (οὐρά) meaning "tail", after the thick-ringed tail characteristic of all Cyclura.[1] The Rhinoceros Iguana's specific name, cornuta, is from from the Latin word cornutus, meaning "horned" and refers to the horned projections on the snouts of males of the species. The species was first identified by Pierre Joseph Bonnaterre in 1789.[2][3]
There are two subspecies of Cyclura cornuta, the Mona Ground Iguana (Cyclura cornuta stejnegeri) and the Navassa Island Iguana (Cyclura cornuta onchiopsis), although the latter species is believed to be extinct in the wild.[4][3]
Anatomy and morphology
The Rhinoceros Iguana, like other members of the genus Cyclura, is a large bodied, heavy headed lizard with strong legs and a vertically flattened tail[5]. A crest of pointed horned scales extends from the nape of their neck to the tip of their tail[5]. Their color is a uniform gray to brown drab.[5]
These iguanas are characterized by the growth of bony prominent tubercles on their snouts which resemble horns.[6] Dr. Thomas Wiewandt, who spent an extended period on Mona Island studying Cyclura cornuta stejnegeri, suggested that the horns, along with lateral spines and prominent parietal bulges, function as protective armor against sharp rocks or as defensive tools to facilitate the escape of males from the grasp of one another.[6][7] Males possess an adipose pad in the form of a helmet on the occipital region of the head, and a large dewlap. Males of this species, like other species within the Genus Cyclura, are larger than females, and have more prominent dorsal crests and "horns" in addition to femoral pores on their thighs, which are used to release pheromones. Females lack these pores and have shorter crests than the males, making the animals sexually dimorphic.
