Syncesia madagascariensis is a rare species of crustose lichen in the family Roccellaceae.

Found in Madagascar, it was formally described as a new species in 2010 by Damien Ertz, Dorothee Killmann, Tahina Razafindrahaja, Emmanuël Sérusiaux, and Eberhard Fischer.

The type specimen was collected south of Ambositra in Ankazomivady (Ambalamanakana) at an altitude of 1,705 m (5,594 ft).

It is only known to occur at the type locality, where it grows on tree trunks in a montane forest of mostly Myrtaceae and Syzygium.

[1] The lichen has a crustose, water-repellent thallus that is creamy with a greenish tinge and measures up to 15 cm (6 in) in diameter.