Cryptoendolith communities in Antarctic dry valley region sandstones: Potential analogues of Martian life-forms

Introduction: Cryptoendolithic communities colonizing sandstones in the Dry Valleys of Antarctica have been the subject of much research over recent years, owing to their potential as analogues of Martian life-forms. Interest in them stems from the similarities between the Antarctic cold desert ecosystems, representing some of the most extreme of terrestrial environmental habitats, and the conditions pertaining at the Martian surface [1]. Cryptoendolithic microbial communities occur in the interstitial spaces of certain translucent sandstones [2, 3] and extend down to 10mm below the rock surface (Figure 1). They primarily consist of symbiotic or free living lichen and cyanobacteria and their presence is identified by three coloured zones in the profile of the substratum: 1) black pigmented lichen; 2) white lichen, predominantly hyaline fungi; and, 3) microalgae (green algae and/or cyanobacteria) [4].