The lichen family Physciaceae in Thailand-II. Contributions to the genus Heterodermia sensu lato Author Mongkolsuk, Pachara Lichen Research Unit, Biology Department, Faculty of Science, Ramkhamhaeng University, Ramkhamhaeng 24 road, Bangkok, 10240 Thailand. Author Meesim, Sanya Lichen Research Unit, Biology Department, Faculty of Science, Ramkhamhaeng University, Ramkhamhaeng 24 road, Bangkok, 10240 Thailand. Author Poengsungnoen, Vasun Lichen Research Unit, Biology Department, Faculty of Science, Ramkhamhaeng University, Ramkhamhaeng 24 road, Bangkok, 10240 Thailand. Author Buaruang, Kawinnat Lichen Research Unit, Biology Department, Faculty of Science, Ramkhamhaeng University, Ramkhamhaeng 24 road, Bangkok, 10240 Thailand. Author Schumm, Felix Mozartstrasse 9, D- 73117 Wangen, Germany. Author Kalb, Klaus Lichen Research Unit, Biology Department, Faculty of Science, Ramkhamhaeng University, Ramkhamhaeng 24 road, Bangkok, 10240 Thailand. & Lichenologisches Institut Neumarkt, Im Tal 12, D- 92318 Neumarkt, Germany. Email: klaus. kalb @ arcor. de & Lichen Research Unit, Biology Department, Faculty of Science, Ramkhamhaeng University, Ramkhamhaeng 24 road, Bangkok, 10240 Thailand. & University of Regensburg, Institute of Plant Sciences, Universitätsstraβe 31, D- 39040 Regensburg, Germany Corresponding author-email: pm-tamrapap @ ru. ac. th & Lichen Research Unit, Biology Department, Faculty of Science, Ramkhamhaeng University, Ramkhamhaeng 24 road, Bangkok, 10240 Thailand. klaus.kalb@arcor.de text Phytotaxa 2015 2015-11-20 235 1 448 450 http://dx.doi.org/10.11646/phytotaxa.235.1.1 journal article 10.11646/phytotaxa.235.1.1 1179-3163 13631327 Leucodermia Kalb , gen. nov. Mycobank MB 813825 Synonym: Anaptychia Körb. sect. Polyblastidium Kurok. ser. leucomelaenae Kurok., Beih. Nova Hedwigia 6: 8 (1962) . Type species:— Leucodermia leucomelos (L.) Kalb; Lichen leucomelos L., Sp. Pl., ed. 2, 2: 1613 (1763). America meridionali (LINN 1273.109, holotype n.v., fide Jørgensen et al. 1994: 329 , 378). Etymology :—The generic name has been combined from ser. leuco melaenae and Hetero dermia . The new genus is characterized by a loosely adnate or, in part, unattached thallus with ribbon-like, linear elongate, dichotomously branched lobes with conspicuous long marginal rhizines, a paraplectenchymatous upper cortex and a lower ecorticated surface. Apothecia stipitate with triangular lobules, disc brown, ± densely whitish to gray pruinose. Ascospores brown, of Polyblastidia - type , with sporoblastidia. Remarks : — Leucodermia is closely related to Heterodermia comosa -group, but differs mainly in having linear elongate, dichotomously branched lobes and a foliose to subfruticose thallus. In contrast, the lobes in H. comosagroup are usually ascending, spathulate or paddle-shaped.