Lilloa (Dec 2007)
The lichen Caloplaca felipponei growing on quartz sandstone in Mar del Plata (Argentina): SEM observations
Abstract
Rosato, Vilma G. 2007. “The lichen Caloplaca felipponei growing on quartz sandstone in Mar del Plata (Argentina): SEM observations”. Lilloa 44 (1-2). Caloplaca felipponei Zahlbr. (Teloschistales, Teloschistaceae) is a lichen species growing on rocks in Mar del Plata (Buenos Aires Province, Argentina), with bright orange-red colonies that contrast with the colour of the substratum. It densely colonizes quartz sandstone slabs decorating the building formerly used by INIDEP (National Institute of Fisheries Research). Small rock specimens were obtained and left with the lichen; others were treated with hydrogen peroxide to remove organic matter. These samples, as well as non-colonized rock specimens, were covered with gold in a sputter and observed under Scanning Electron Microscope (SEM). Electron Dispersive Spectrometry (EDS) microanalyses were also performed. The rock is hard and compact, and the lichen can penetrate it only up to 70 µm. However, the areolae of the thallus are inmersed in the rock up to 150 mm, creating mesopits. As regards EDS microanalyses results, no evidence of a chemical action of the lichen could be found, though this should be confirmed with X-ray diffraction studies. In conclusion, C. felipponei affects the rock mainly by mechanical action, causing mostly mesopits (Small pits visible to the naked eye). There is also an aesthetical damage, but in this case the lichen colonies add colour to the building.
