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Squamata · XenosauridaeEntry 21,457 of 21,572
Knob-scaled Lizard, Xenosaurus grandis

Reptilia · Squamata

Xenosaurus grandisGray, 1856

Knob-scaled Lizard

Identification not confirmed. One observer recorded this animal as this species and no one has since agreed, so the photograph may show a different animal.

Photograph by Liliana Ramírez-Freire, CC BY, via iNaturalist

A rock-dwelling, day-active, meat-eating lizard from the Neotropic region, reaching 133 mm snout to vent.

Reptilia › Squamata › Xenosauridae › Xenosaurus

Grows to
133mm
greatest recorded
Eats
Carnivorous
Active
Diurnal
Lives up to
12.8years

What is known

43 sourced facts, each taken from a named scientific dataset. How to read these.

Cited from a dataset unless a row is marked otherwise.

Standing in the world

Still living
Extant
Conservation status
Vulnerable
Status assessed · the year the Red List last looked
2007
Population trend
Decreasing
Red List criteria
B1ab(iii,v)

The animal itself

Limbs
Four legs
Venomous
No
Fangs
None
Longest recorded life
12.8years

Slavens and Slavens 1999

Preferred body temperature · chosen in a laboratory gradientmeasured
25.6°C
Body temperature when active · measured in the wild
22.55°C73 °F

mean body temperature of active individuals in nature

Body temp in the wild · mean, when active
21.4–22.7°C71–73 °F

body temperature of active animals in nature

Size

Length snout to vent · greatest recorded
133mm5.25 in

max 133 mm SVL (Feldman et al. 2016)

Length snout to vent · adult female mean
110.9mm4.25 in
Largest female · snout to vent
110.9mm4.25 in

snout-vent length; the source column mixes this with straight carapace length

Hatchling length · snout to vent
45mm1.75 in
Largest juvenile · snout to vent
45mm1.75 in
Body mass · greatestcomputed
56.4g2 oz

computed from length by a family-level allometric equation, not weighed

How it lives

Diet
Carnivorous

Arthropods, gastropods and small lizards (see Lemos-Espinal et al. 2012, Lemos-Espinal 2003), a salamander (Cazares-Hernandez et al. 2017)

How it hunts
Sit and wait

Mesquita et al. 2016, also implied by Lemos Espinal 2003

Active
Diurnal
Where it lives
Saxicolous

(e.g., Mesquita et al. 2016), and Leaf Litter?

Habitat
Forest, Rocky, Shrubland
Biome
Tropical & Subtropical Moist Broadleaf Forests
Region
Neotropic
Mainland or island
Mainland
Elevation · above sea level
720–1800m

Gadsden and Woolrich-Pina 2017: 1100, Woolrich-Pina et al. 2020: 1040

Range size
5387km²
Density
8.8–135per hectare

Breeding

Reproduction
Viviparous
Average clutch
3.9eggs
Eggs or young per clutch
1–8eggs

2.7-5.1 neonates, Zuniga-Vega 2011, mean 3.2 (Lemos-Espinal et al. 2003) SEE ALSO Zamora-Abrego et al. 2007, 2-8, mean 5.1 (Lemos Espinal 2003), mean 5.1-5.7, 2.7 in X. g. agrenon (Woolrich-Pina et al. 2014), means 2.1-5.7 (Mesquita et al. 2016), mean 5l.1 (Zuniga-Vega et al. 2017)

Mean clutch
2.1–5.7eggs
Clutches in a year
0.42per year
Clutches a year
0.33–0.5per year
First breeds at
32months

Naming and history

Suborder
Sauria
Infraorder
Anguimoprha
Subspecies
Xenosaurus grandis grandis (GRAY 1856) Xenosaurus grandis sanmartinensis WERLER & SHANNON 1961
Described by
Gray
Moved to another genus · since it was first described
Yes
Described in
1856
Type locality
Mexico

Keeping one

Knob-scaled Lizard is assessed as Vulnerable on the IUCN Red List. Species at risk in the wild are often covered by CITES and by national law, which decide what may be bought, sold, moved across a border or kept at all — and captive-bred and wild-caught animals are usually treated differently. Check the rules where you are before acquiring one. Nothing below is a judgement about keeping this species; it is what a published welfare standard says about space, and what the animal itself was measured doing.

21 in × 21 in × 13 in(53 × 53 × 33 cm)

Minimum length × width × height, for one animal. Bigger is always better.

The standard sizes ground-dwelling species at 4 × 4 × 2.5 times snout-vent length.

Lives on rock, so stable hard surfaces and basking ledges suit it.

Mindestanforderungen an die Haltung von Reptilien (Sachverständigengutachten), German Federal Ministry for Nutrition, Agriculture and Forestry, Animal Welfare Division, 10 January 1997. The standard states these floor areas are recommendations rather than binding limits.

From this animal’s own snout-vent length of 5.25 in (133 mm), at 4 × 4 × 2.5 times it, following the German federal welfare standard — how this is worked out.

In a laboratory thermal gradient this species settled at 78 °F (25.6 °C).

Preferred body temperature, recorded in a laboratory gradient where the animal could choose freely. A measurement of the animal, not a setting for a thermostat.

Feeding

A prey item should be no wider than the space between the animal's eyes.

Widely used across reptile husbandry references. The stated reason is that the gap approximates the width of the throat, so wider prey is associated with impaction. This is established practice, not a measurement.

7kJ per day

Worked out for an animal of 56 g, the heaviest recorded for Knob-scaled Lizard — so it is the top of the range, not a figure for a particular animal. Weigh yours and the number will be lower.

An upper estimate, not a feeding target, and not veterinary advice. The equation covers only what an animal burns staying alive, so a growing, gravid or recovering animal needs more — and it was measured on wild animals, which move far more than one in an enclosure. Body condition and a vet who knows the species are what a feeding decision should rest on. Where this comes from.

What nobody knows

These are not gaps in our research. No scientific dataset records them for this species — and saying so is information you cannot get from a reference that simply leaves a field out.

  • — Length snout to vent · adult male mean
  • — Length snout to vent · adult mean
  • — Length nose to tail · greatest recorded
  • — Female length · mean, nose to tail
  • — Length nose to tail · adult male mean
  • — Length nose to tail · adult mean
  • — Largest male · snout to vent
  • — Largest female · shell length
  • — Largest male · shell length
  • — Hatchling length · nose to tail
  • — Largest juvenile · shell length
  • — Egg length
  • — Egg width
  • — Body mass · a typical adult
  • — Body mass · adult female, mean
  • — Body mass at hatching
  • — Eats arthropods
  • — Eats vertebrates
  • — Eats plant matter
  • — How the young develop
  • — Gestation or incubation
  • — Hatchling length · smallest recorded
  • — Hatchling length · largest recorded
  • — Age at first breeding · female
  • — Mature from · youngest recorded
  • — Mature by · oldest recorded
  • — Size at maturity · smallest recorded
  • — Size at maturity · largest recorded
  • — Colour on the back
  • — Pattern on the back
  • — Pupil
  • — Sex decided by
  • — Active season · shortest recorded
  • — Active season · longest recorded
  • — Home range · largest recorded
  • — Active in

Others in Xenosauridae

Take this data

Everything on this page is available as data under CC BY 4.0 — use it freely, credit it, no permission needed.

This species as JSON · the whole dataset

Cite this page

The Reptile & Amphibian Encyclopedia (2026). Xenosaurus grandis. Retrieved 2026-09-08, from https://www.allanglescreatures.com/species/xenosaurus-grandis

@misc{xenosaurus_grandis_2026,
  title  = {Xenosaurus grandis},
  author = {{The Reptile & Amphibian Encyclopedia}},
  year   = {2026},
  url    = {https://www.allanglescreatures.com/species/xenosaurus-grandis}
}

Sources

  1. Meiri, S. (2024). SquamBase — a database of squamate (Reptilia: Squamata) traits. Global Ecology and Biogeography. Public domain (CC0).
  2. Oskyrko, O. et al. (2024). ReptTraits: a comprehensive dataset of ecological traits in reptiles. Scientific Data. Used under CC BY 4.0.
  3. Catalogue of Life (dataset 3LR), used under CC BY.