Abronia graminea (Cope, 1864)

Common Name & Body Shape

Abronia graminea, commonly called the Mexican alligator lizard, has a dorsoventrally flattened body, a flattened triangular head, and a weak lateral fold.

Size Measurements

It reaches a maximum snout–vent length of about 10.6 cm (4.2 in), and maximum tail length of 16.0 cm (6.3 in).

Weight Records

Two recorded specimens had weights matching their sizes: one with a 9.8 cm (3.9 in) snout–vent length weighed 21.2 g (0.75 oz), and another with a 10.0 cm (3.9 in) snout–vent length weighed 20.7 g (0.73 oz).

Locomotor Adaptations

This species has a prehensile tail that can regrow if lost, plus long strong limbs and digits suited to its arboreal (tree-dwelling) lifestyle.

Coloration Age Difference

Adult coloration differs noticeably from juvenile coloration.

Adult Base Coloration

Adult males are usually bright emerald green, while adult females have dorsal coloration ranging from bright to dull orange.

Adult Additional Color Features

Additional color features seen in adult individuals include bright yellow skin around the eyes, blue markings on the supralabial scales, and yellow coloring on the snout, lower jaw, and throat.

Dorsal Scale Pigment

The basal half of each dorsal scale has varying amounts of dark pigment.

Female Retained Juvenile Pattern

Females occasionally keep the dark crossband pattern that is characteristic of juvenile coloration.

Juvenile Coloration

Juveniles usually have a light tan base body color with 9 irregular black crossbands on the body and 19 on the tail, plus a dirty yellow belly.

Scale Count Pattern

The typical scale pattern for A. graminea is as follows: 12 longitudinal rows of ventral scales, 25 to 29 transverse dorsal scale rows, 4 to 6 longitudinal nuchal scale rows, 12 to 14 longitudinal dorsal scale rows, 11 supralabial scales, and 2 rows of infralabial scales (5 scales in the first row, 6 scales in the second row).

Scale Texture Characteristics

Preauricular scales are granular, dorsal scales are slightly keeled, head plates are often thickened and rough (creating the species' triangular head shape), and dorsal scales are typically larger than ventral scales.

Endemic Distribution Range

The Mexican alligator lizard is widely distributed but endemic to the highlands of Mexico along the Sierra Madre de Oaxaca mountain range.

Distribution Area & States

Its total estimated distribution area is approximately 11,500 km², covering the Mexican states of Puebla, Veracruz, and Oaxaca.

Elevation Range

It inhabits areas at elevations between 1,350 and 2,743 meters above sea level.

Forest Habitat Type

This species lives in mesic montane forest environments, most commonly in cloud forests or pine-oak forests with humid temperate climates that often see large temperature differences between day and night.

Arboreal Microhabitat

As an arboreal species, it lives among epiphytic vegetation, especially bromeliads, but also lichens and orchids.

Canopy Position & Habitat Tolerance

It can be found as high as 40 meters up in forest canopies, and cannot survive in degraded habitats.

Reproductive Mode

A. graminea is viviparous, meaning it gives birth to live young.

Sexual Maturity & Litter Size

Females usually reach sexual maturity in their third year of life, and can give birth to litters of 1 to 12 offspring.

Mating & Birth Timing

While copulation has not been observed in the wild, mating is thought to occur in summer or fall, with birth taking place in the spring.

Gestation Period

The gestation period lasts approximately 6 to 8 months.