The lichen family Physciaceae in Thailand-I. The genus Pyxine Author Mongkolsuk, Pachara Lichen Research Unit, Biology Department, Faculty of Science, Ramkhamhaeng University, Ramkhamhaeng road 24, Bangkok, 10240 Thailand. Email: pm-tamrapap @ ru. ac. th Author Meesim, Sanya Lichen Research Unit, Biology Department, Faculty of Science, Ramkhamhaeng University, Ramkhamhaeng road 24, Bangkok, 10240 Thailand. Email: pm-tamrapap @ ru. ac. th Author Poengsungnoen, Vasun Lichen Research Unit, Biology Department, Faculty of Science, Ramkhamhaeng University, Ramkhamhaeng road 24, Bangkok, 10240 Thailand. Email: pm-tamrapap @ ru. ac. th Author Kalb, Klaus Lichenologisches Institut Neumarkt, Im Tal 12, D- 92318 Neumarkt, Germany. Email: klaus. kalb @ arcor. de & University of Regensburg, Institute for Botany, Universitätsstra e 31, D- 39040 Regensburg, Germany text Phytotaxa 2012 2012-07-13 59 1 32 54 http://biotaxa.org/Phytotaxa/article/view/phytotaxa.59.1.2 journal article 10.11646/phytotaxa.59.1.2 1179-3163 5061495 20. Pyxine subcoralligera Kalb, Mongkolsuk & Boonpragob sp. nov. ( Fig. 3D ) Mycobank MB 800695 Similar to Pyxine coralligera Malme , but containing a different array of terpenes, and having concave lobes with ± marginal pseudocyphellae which do not become reticulate. Holotype :— THAILAND . Chiang Mai ; Queen Sirikit Botanic Garden , in a dry dipterocarp forest, on Syzygium claviflora , 750 m , 18°53'54'' N , 98°51'38'' E , 1 July 1994 , Boonpragob 2665 ( RAMK 17615 ). Thallus corticolous and saxicolous, 1–3 cm wide, loosely to tightly adnate. Lobes radiating, discrete to ± contiguous, plane to slightly concave, 0.5–1.0 mm wide, subrotund to truncate at the apices. Upper surface pale to dark grey or brownish to greenish grey, epruinose; true isidia and soralia absent. Pseudocyphellae marginal, rarely spreading to the upper surface, not becoming reticulate. Polysidiangia slender, mainly marginal, occasionally laminal, scattered or clustered, nodular to subcylindrical or clavate, short, ± branched, pustulate, bursting apically to release corticate fragments, no soredia. Medulla (upper part) creamy yellow to yellow-orange or yellow-brown, lower part white. Lower surface black in the centre, paler towards the margin; rhizines ± dense, simple or irregularly branched. Apothecia and pycnidia not seen. Chemistry: Cortex K+ yellow, C-, KC-, P+ yellow, UV-; medulla upper part: K-, C-, P+ orange, lower part: all spot tests negative; containing atranorin (major), chloroatranorin (minor), testacein (major), unknown terpenes (minor). Distribution and habitat :—A rare species, on bark and rocks in dry dipterocarp, dry evergreen and mixed deciduous forests. So far known only from Thailand , where it occurs at 390–750 m elevation. Notes :— P. subcoralligera is characterized by the marginal polysidiangia, cortical atranorin, the pale yellow to yellow-orange medulla, and by the presence of medullary testacein and a characteristic array of terpenes. It is morphologically similar to P. coralligera , but the latter differs in containing a different suite of terpenes, convex lobes with distinct, irregular to linear laminal pseudocyphellae, which become ± reticulate subapically. P.maculata is also similar, but this species is characterized by reticulate laminal pseudocyphellae. Material from Thailand examined :— Loei ; Na Haeo National Park , in a dry dipterocarp forest on Neolithea sp., 540 m , 17°28'40'' N , 100°03'30'' E , 15 July 1995 , P . Mongkolsuk 6378 ( RAMK 17628 ).— Loei ; Phu Luang Wildlife Sanctuary , Huai Baeng Forest Ranger Station , in a dry evergreen forest on an unidentified tree, 390 m , 17°16'48'' N , 101°34'00'' E , S . Meesim 745 ( RAMK 16306 ).— Nakhon Ratchasima ; Khao Yai National Park , creek to Heaw Plakung waterfall, in a mixed deciduous forest on rock, 580 m , 14°31'25'' N , 101°16'22'' E , 28 June 2000 , W . Polyiam 20722 ( RAMK 17627 ) .