ON RHIZOCARPON VIRIDIATRUM (WULFEN) KÖRB. IN NORTH-EASTERN IRAN

Introduction The lichen genus Rhizocarpon introduced by Ramond in Flore Francaise ed. III (Lamarck and Candolle, 1805) has been subject to taxonomic debate. Originally its species were included in Lecidea, Buellia and Diplotomma. Since 1871 new attempts have been made to delimit a separate genus Rhizocarpon Lam. ex DC. as a cosmopolitan with ca. 200 species (Feuerer, 1978). Traditionally the genus is divided in a group of species with yellow-green thallus and a group with non-yellowgreen, generally grayish or brownish thallus (Thomson, 1967). The yellow group is distributed in the Arctic and the Antarctic and the temperate zones of the world, as well as at high elevations in the mountains of warmer zones (Runemark, 1956). The presence of the genus in Iran is very poorly known, as is knowledge generally for lichens, while recent investigations are beginning to change that situation. The lichenological knowledge in Iran experienced a considerable improvement in the last decade (Seaward et al., 2004; 2008). As a result, the presence of ten species and one subspecies of Rhizocarpon in Iran, including six species for Razavi Khorasan province, have been reported (Seaward et al. 2008; Moniri et al. 2009). Razavi Khorasan province in the northeast of Iran with an area of c. 127,432 km biogeographically belongs to Irano-Touranian region (Takhtajan, 1977). Razavi and Northern Khorasan provinces have more mountain ranges than any other parts in the country, including Ala Dagh, Binaloud, Hazar Masjid and Kopet Dagh (Zomorodian, 2002), and certainly they must have a greater saxicolous lichen diversity than the little attention to the area has revealed so far. The present study is a continuation of our analyses of Rhizocarpon in Razavi Khorasan province (Haji Moniri et al., 2010; Haji Moniri & Kamyabi, 2010), and deals with morphology, anatomy, chemistry and distribution of R. viridiatrum (Wulfen) Korb. The ecology is not yet included because more extensive sampling of other regions of the province, especially mountainous zones, as well as microhabitat studies are needed to improve our knowledge of the species. Archive of SID