Adult Galápagos lava lizards range from around 50 to 100 mm long SVL (snout-to-vent length; excluding tail which can be equal or longer to SVL), with average and maximum sizes varying between islands.
Males are on average larger than females, being twice to three times as heavy, with average body sizes of 77 to 91 mm SVL, compared to 63–71 mm of females.
In addition to size, there are significant color and morphological differences between sexes, although color varies across islands.
Males are blue gray to brownish, spotted black to ash gray, and tend to have dark crossbands on the neck and anterior portion of the back.
The throat has a large black blotch, extending to the base of the forelimbs.
Males have a crest of spined scales running down the length of the body, which are longer than those of females.
Males also have proportionally longer hind legs.

Females are largely unmarked or have light speckles, and lack the dark crossbars of males, although may have dark banding on tail, especially young females.
Adult females lack the black throat blotch of males, and instead have a distinctive "cheek patch": a patch of salmon, orange, or brick red extending from the base of the front legs to the snout, and up to the eye.
The cheek patch appears as females attain reproductive maturity.
Adult Galápagos lava lizards range from around 50 to 100 mm long SVL (snout-to-vent length; excluding tail which can be equal or longer to SVL), with average and maximum sizes varying between islands. Males are on average larger than females, being twice to three times as heavy, with average body sizes of 77 to 91 mm SVL, compared to 63–71 mm of females. In addition to size, there are significant color and morphological differences between sexes, although color varies across islands. Males are blue gray to brownish, spotted black to ash gray, and tend to have dark crossbands on the neck and anterior portion of the back. The throat has a large black blotch, extending to the base of the forelimbs. Males have a crest of spined scales running down the length of the body, which are longer than those of females. Males also have proportionally longer hind legs.
Females are largely unmarked or have light speckles, and lack the dark crossbars of males, although may have dark banding on tail, especially young females. Adult females lack the black throat blotch of males, and instead have a distinctive "cheek patch": a patch of salmon, orange, or brick red extending from the base of the front legs to the snout, and up to the eye. The cheek patch appears as females attain reproductive maturity.
Microlophus albemarlensis