Xenus lithophylli
Xenus lithophylli is a species of lichenized ascomycete fungus discovered in 1992, composing the entire monotypic genus Xenus. It is found parasiting the calcified algae Lithophyllum, and lives attached to corals in Belize, in the Caribbean. This species is currently under incertae sedis in the order Pyrenulales. References

Lichen species
Pyrenulales
Lichens described in 1992