Chrysothrix septemseptata is a species of crustose lichen in the family Arthoniaceae.

The type specimen was collected in the Sundarbans Biosphere Reserve (West Bengal); here it was found growing on the bark of the mangrove tree Tamarix gallica.

The lichen grows as a thin lemon-yellow crust measuring 0.5–2 cm (0.2–0.8 in) in diameter, with isolated patches sometimes coalescing.

It contains vulpinic acid as a major secondary chemical, and minor amounts of calycin.

The specific epithet septemseptata refers to the seven septa that are characteristic of the ascospores of this lichen.