Xenosaurus grandis (Gray, 1856)

Common Name and Endemic Range

Xenosaurus grandis, commonly called the knob-scaled lizard, is a species of diurnal, terrestrial lizard that is endemic to Mexico and Guatemala.

Core Rainforest Habitat and Diet

It primarily lives in tropical rainforests, where it dwells in rock crevices and feeds on insects.

Major Population Zones

The species has five distinct major population zones across southern Mexico and Guatemala: central Veracruz, southern Oaxaca, north-central Oaxaca, the highlands of central Chiapas, and central Guatemala.

Recognized Subspecies

These isolated population groups have resulted in the recognition of five subspecies of X. grandis: X. g. grandis, X. g. agrenon, X. g. arboreus, X. g. rackhami, and X. g. sanmartinesis.

Crevice Dwelling Habitat Adaptation

All subspecies of Xenosaurus grandis live exclusively in rock crevices, a trait that lets the species occupy a wide range of habitats including xerophytic vegetation, tropical rainforests, cloud forests, oak forests, and tropical deciduous rainforests.

Site Fidelity

These lizards have very strong site fidelity: 95% of their entire lives are spent in just one to two rock crevices.

Reproductive Mode

Like all other xenosaurids, Xenosaurus grandis is viviparous, meaning it gives birth to live young instead of laying eggs.

Gestation Period

Gestation lasts for 9 months before young are born.

Litter Size

Most litters contain just three offspring, though litter sizes from two to seven have been recorded.

Sexual Maturity Age

Males of this species reach sexual maturity at 28 months, while females reach maturity slightly later, at 32 months.

Offspring Production Frequency

Current evidence suggests X. grandis does not produce offspring every year.