A novel subaerial Dunaliella species growing on cave spiderwebs in the Atacama Desert.

Strategies for life adaptation to extreme environments often lead to novel solutions. As an example of this assertion, here we describe the first species of the well-known genus of green unicellular alga Dunaliella able to thrive in a subaerial habitat. All previously reported members of this microalga are found in extremely saline aquatic environments. Strikingly, the new species was found on the walls of a cave located in the Atacama Desert (Chile). Moreover, on further inspection we noticed that it grows upon spiderwebs attached to the walls of the entrance-twilight transition zone of the cave. This peculiar growth habitat suggests that this Dunaliella species uses air moisture condensing on the spiderweb silk threads as a source of water for doing photosynthesis in the driest desert of the world. This process of adaptation recapitulates the transition that allowed land colonization by primitive plants and shows an unexpected way of expansion of the life habitability range by a microbial species.