These geckos are part of the Phelsuma group, which consists of in excess of 70 species and subspecies.

They are commonly referred to as the Madagascar giant day gecko, due to their large size.

The species Phelsuma grandis described by Gray 1870 was elevated from subspecies status (P. madagascariensis grandis) by Raxworthy et al. in 2007,[3] after environmental niche modeling revealed significant and reliable differences between it and other members of the P. madagascariensis-clade.

These red markings are quite variable, and in some cases, completely absent, though the line extending from the nostril to the eye is always present.

Young individuals of the species often exhibit much more red than their parents, but as time passes, many of the markings fade, to leave those that will stay for the remainder of the gecko's life.

When stressed, the colouration darkens, rendering the whole animal a dark green, and the red markings on the face and back more orange in hue.

Breeding behavior includes, the shaking of the tail or body, vocalizing, and if the female does not accept the male she may turn a darker green.

[14] These day geckos feed on various insects and other invertebrates, and occasionally have been recorded consuming small vertebrates.