TAXONOMICAL AND ECOLOGICAL ANALYSIS OF REDDISH PATINAS OF TRENTEPOHLIA UMBRINA (KÜTZING) BORNET GROWING ON STONE SURFACES IN LAZIO (ITALY)

Stone surfaces can be subjected to biodeterioration due to the growth of photosynthetic organisms where favourable conditions of the environment and specific substrate materials are present. In this work, we investigated through genetic analysis and ecological observations the widely occurring reddish patinas, which are spread on stones in particular environmental conditions. We collected patina occurrence and environmental data at sites in the Lazio region covering an altitude range of 0 to 650 m asl and distances up to 70 km from the coast to define the ecological range. The results of blast analysis of DNA sequences confirmed a dominant presence of the filamentous terrestrial green alga Trentepohlia umbrina (Kützing) Bornet in all sites, sometimes mixed to cyanobacteria of the genus Gloeocapsa. In one site we identified T. aurea (L.) C. Martius, which occurs in different micro-environmental conditions. Originally the distribution of Trentepohliales was given as pan-tropical, but some temperate taxa have now been identified, such as T. umbrina. Preferred environmental conditions of this species were a relatively low humidity, vertical (or near vertical) surfaces, temporal diurnal shade-exposure and a mainly northern aspect. Coastal areas were more favourable for its growth, as the patinas were much more developed compared to sites further inland. Cement materials and mortars resulted particularly bioreceptive, possibly due to their soluble salt content, but tuffs and marble were also colonised under favourable conditions. The findings here suggest that the ecological preference of this species is wider than previously thought and urges the need for detailed studies on its biodeteriogenic nature.