Myxomycetes of Thailand Thida Win Ko Ko Department of Biology Chiang Mai University Chiang Mai 50200 Thailand Tran Thi My Hanh School of Biotechnology Ho Chi Minh International University Ho Chi Minh City Vietnam Steven L. Stephenson Department of Biological Sciences University of Arkansas Fayetteville, Arkansas 72701 United States David W. Mitchell Walton Cottage Upper Hartfield East Sussex TN7 4AN England Carlos Rojas Department of Biological Sciences University of Arkansas Fayetteville, Arkansas 72701 United States Kevin D. Hyde School of Science Mae Fah Luang University Chiang Rai 57100 Thailand S. Lumyoung Department of Biology? Chiang Mai University Chiang Mai 50200 Thailand 1 Abstract After the first report of myxomycetes from Thailand in 1902, there were only a few papers dealing specifically with these organisms over the period of the next 85 years. In 2004, intensive ecological studies of myxomycetes began at the Mushroom Research Centre north of Chiang Mai. These studies, which considered both specimens that had fruited under natural conditions in the field as well as those appearing in moist chamber cultures prepared with various types of dead plant material, yielded numerous new records for Thailand. At least 132 species of myxomycetes in 30 genera are now known to occur in the country. This total includes several species reported from only a few other localities worldwide. An annotated checklist based on all published and unpublished records is provided herein. INTRODUCTION The myxomycetes (plasmodial slime molds or myxogastrids) are a group of fungus-like organisms usually present and sometimes abundant in terrestrial ecosystems (Martin & Alexopoulos 1969). The exact evolutionary affinities of the myxomycetes are still debated, but these organisms constitute a well-defined and homogenous group of approximately 875 species (Lado 2001). The reproductive, or spore-producing, stage in the myxomycete life cycle can achieve macroscopic dimensions and be collected and preserved for study in much the same way as the sporocarps of fungi. However, most species of myxomycetes tend to be rather inconspicuous or sporadic in their occurrence and thus not always easy to detect in the field. Moreover, fruiting bodies of most species are relatively ephemeral and do not persist in nature for very long. Myxomycetes also spend a portion of their life cycle as true eukaryotic microorganisms, when their very presence in a given microhabitat can be exceedingly difficult if not impossible to determine. Because of their life history strategy and inconspicuous nature, myxomycetes provide an immense challenge in biodiversity assessments and, consequently, often have been neglected in such studies. The first report of myxomycetes from Thailand appears to be that of Rostrup (1902), who listed Lycogala epidendrum and Stemonitis fusca from Koh Chang Island in the Gulf of Thailand. Hein (1962) briefly referred the abundance of these organisms in Thailand, but the first significant contribution to our knowledge of the myxomycete biota was a series of specimens collected in April to June of 1967 by Emory Simmons and deposited in the National Fungus Collections (BPI) in Beltsville, Maryland. These specimens, along with a number of additional specimens collected by Don Reynolds in Thailand during the summer of 1967, were reported by Reynolds and Alexopoulos (1971). The total number of species they listed was 42. All of these records were from localities in central and southern Thailand. Siwasin and Ing (1982) reported 34 species of myxomycetes, mostly from northern Thailand, and 16 of these were new records for the country. Later, Ing et al. (1987) listed 17 species that had been collected in dipterocarp forests in central Thailand, but all of these had been reported previously. In 2004, intensive studies of myxomycetes began at the Mushroom Research Centre north of Chiang Mai. These studies, which considered both specimens that had fruited under natural conditions in the 2 field as well as those appearing in moist chamber cultures prepared with various types of dead plant material, yielded a considerable body of information on the distribution and occurrence of myxomycetes in the forests of northern Thailand (Tran et al. 2006, 2008; Ko Ko et al. 2009, 2010) as well as a number of new records for the country. Several of these are species reported from only a few localities worldwide. The purpose of this paper is to provide an annotated checklist of all myxomycetes now known to occur in Thailand. We hope that this effort will prompt future studies to document more completely the myxomycete biota of other neighboring countries in Southeast Asia. Thailand, with at total area of 514,000 km2, is comparable in size to France and somewhat larger than the state of California in the United States. The country is home to several distinct geographic regions. The northern part of the country is mountainous, with the highest point being Doi Inthanon at 2,565 m (8,415 ft). The northeastern part of Thailand consists of the Khorat Plateau, bordered to the east by the Mekong river. The center of the country is dominated by the predominantly flat Chao Phraya River Valley, which runs into the Gulf of Thailand. The southern part consists of the narrow Kra Isthmus that widens into the Malay Peninsula. The climate throughout the country is tropical and characterized by monsoons. The northeat monsoon extends from October/November to February/March, whereas the southwest monsoon lasts from April/May to October. Northern Thailand has three distinct seasons (rainy from May to October, cool-dry from November to February, and hot-dry from March through April. The southern isthmus is always hot and humid. Temperatures vary considerably with the season, latitude and elevation. Frost can occur in the northern mountains but afternoon temperatures can exceed 40 C in other parts of the country. No comprehensive and generally accepted classification of the vegetation of Thailand exists, but forest types that have been recognized include such diverse examples as tropical rain forest, evergreen monsoon forest, deciduous monsoon forest, dry forest, pine-oak forest and coastal mangrove forest. Total forest cover has steadily declined over the past century as a result of such factors as urban expansion and the demand for agricultural land, and only about 15% of the country is still forested (Maxwell 2004). However, overall botanical biodiversity in Thailand is high, and it would be anticipated that this would be accompanied by high levels of biodiveristy in other groups of organisms, including myxomycetes. Annotated List of Species In the list that follows, myxomycetes recorded from Thailand are arranged alphabetically by genus and then species. Information is provided on the source(s) of each record, along with comments on particularly noteworthy examples. Nomenclature essentially follows Lado (2001) and Lado (2005-2010), with exception of Stemonitis nigrescens and Stemonitis smithii for which the treatment of Martin & Alexopoulos (1969) has been followed. The abbreviation ‘cf.’ in the name of a species indicates that the specimen representing the source of the record could not be identified with certainty. This usually indicates scanty or aberrant material. Specimens of species not reported previously in print as occurring in Thailand are deposited in the herbaria of Chiang Mai University 3 (CMU) or the University of Arkansas (UARK). Collection numbers are those of coauthors Ko Ko (TWKK), Stephenson (SLS),Mitchell (DWM) and Rojas (CR). Arcyria cf. afroalpina Rammeloo First reported from Thailand by Tran et al. (2008). The single most distinctive macroscopic feature of this species is the exceedingly long stalk. Some forms of the very variable Arcyria cinerea can have a long stalk but the latter is relatively straight, whereas the usual situation in A. afroalpina is for the stalk to be flexous. The material from Thailand is limited but does seem to fit the concept of the latter species. Arcyria cinerea (Bull.) Pers. First reported from Thailand by Reynolds and Alexopoulos (1971) and also listed by Siwasin and Ing (1982), Ing et al. (1987) and Tran et al. (2006, 2008). Arcyria denudata (L.) Wettst. First reported from Thailand by Reynolds and Alexopoulos (1971) and also listed by Siwasin and Ing (1982), Ing et al. (1987) and Tran et al. (2006, 2008). Arcyria globosa Schwein. First reported from Thailand by Tran et al. (2006, 2008). Arcyria incarnata (Pers. ex J. F. Gmel.) Pers. First reported from Thailand by Tran et al. (2008) Arcyria insignis Kalch. & Cooke First reported from Thailand by Reynolds and Alexopoulos (1971) and also listed by Siwasin and Ing (1982). Arcyria magna Rex First reported from Thailand by Reynolds and Alexopoulos (1971). Arcyria oerstedii Rostaf. First reported from Thailand by Siwasin and Ing (1982). Badhamia cf. melanospora Speg. First reported from Thailand Tran et al. (2006). 4 Ceratiomyxa fruticulosa (O.F. Mull.) T. Macbr. First reported from Thailand by Reynolds and Alexopoulos (1971) and also listed by Siwasin and Ing (1982) and Tran et al. (2006, 2008). This species is usually considered along with the myxomycetes, but results from molecular studies (Fiore-Donno et al. 2010) indicate that the genus Ceratiomyxa is actually a sister group to the myxomycetes. However, it shares many of the same features and occurs in some of the same habitats as the “true” myxomycetes. There are two other macroscopic members of the genus that appear to be restricted to the tropics, but neither has been recorded thus far from Thailand. Clastoderma debaryanum Blytt. First reported from Thailand by Reynolds and Alexopoulos (1971) and also known from several specimens that appeared in moist chamber culture on plant debris collected at the Mushroom Research Centre. Collaria arcyrionema (Rostaf.) Nann.-Bremek. ex Lado First reported (as Lamproderma arcyrionema Rostaf.) from Thailand by Reynolds and Alexopoulos (1971) and also listed by Siwasin and Ing (1982), Ing et al. (1987) and Tran et al. (2006, 2008). Comatricha alta Preuss First reported from Thailand by Tran et al. (2008). Comatricha elegans (Racib.) G. Lister First reported from Thailand by Reynolds and Alexopoulos (1971) and also listed by Tran et al. (2006, 2008). Comatricha laxa Rostaf. First reported from Thailand by Reynolds and Alexopoulos (1971) and also listed by Tran et al. (2006, 2008). Comatricha nigra (Pers. ex. J.F. Gmel.) J. Schrot. First reported from Thailand by Tran et al. (2006, 2008). Comatricha pulchella (C. Bab.) Rostaf. First reported from Thailand by Tran et al. (2006). 5 Comatricha tenerrima (M.A.Curtis) G. Lister. First reported from Thailand by Reynolds and Alexopoulos (1971) and also listed by Tran et al. (2008). Cornuvia serpula (Wigand) Rostaf. Not reported in print as occurring in Thailand but appearing in moist chamber culture on a sample of forest floor litter collected in a montane tropical forest at the Mushroom Research Centre north of Chiang Mai (19º 34’ N, 99º 26’ E) in 2007, TWKK 530. Cornuvia serpula is a rare species known from only scattered localities throughout the world. Craterium atrolucens Flatau Not reported in print as occurring in Thailand but recorded on forest floor litter in a montane tropical forest, Ban Pha Dang Village north of Chiang Mai (19º 07’ N, 98º 44’ E), 28 June 2007, KWKK 525. Craterium aureum (Schumach.) Rostaf. First reported from Thailand by Tran et al. (2006, 2008). Craterium concinnum Rex First reported from Thailand by Tran et al. (2006, 2008). Craterium leucocephalum (Pers. ex J.F.Gmel.) Ditmar First reported from Thailand by Tran et al. (2006, 2008). Craterium minutum (Leers) Fr. First reported from Thailand by Tran et al. (2006, 2008). Cribraria aurantiaca Schrad. First reported from Thailand by Tran et al. (2006, 2008). Cribraria cancellata (Batsch) Nann.-Bremek. First reported (as Dictydium cancellatum (Batsch) T. Macbr.) from Thailand by Reynolds and Alexopoulos (1971) and also listed by Siwasin and Ing (1982), Ing et al. (1987) and Tran et al. (2006, 2008). Cribraria costata Dhillon & Nann.-Bremek. 6 Not reported in print as occurring in Thailand but recorded from decaying wood in a montane tropical forest on the grounds of the Mushroom Research Centre north of Chiang Mai (19º 34’ N, 99º 26’ E), 20 October 2006, TWKK 202. Cribraria languescens Rex First reported from Thailand by Siwasin and Ing (1982). Cribraria microcarpa (Schard.) Pers. First reported from Thailand by Reynolds and Alexopoulos (1971) and also listed by Ing et al. (1987) and Tran et al. (2006, 2008). Cribraria minutissima Schwein. Not reported in print as occurring in Thailand but appearing in moist chamber culture on bark from Pinus merkusii collected in Doi Inthanon National Park (18º 31’ N, 98º 29’ E) in 2008, DWM 7242a. Cribraria rufa (Roth) Rostaf. First reported from Thailand by Siwasin and Ing (1982). Cribraria tenella Schrad. First reported from Thailand by Tran et al. (2006). As pointed out by Farr (1976), this species and Cribraria intricata Schrad. are morphologically very close, and the two species sometimes seem to be connected by intermediate forms. However, C. tenella tends to be relatively smaller and has a peridial net with few free ends, two features that characterize our material. Cribraria violacea Rex. First reported from Thailand by Reynolds and Alexopoulos (1971) and also listed by Tran et al. (2006, 2008). Diachea bulbillosa (Berk. & Broome) Lister First reported from Thailand by Tran et al. (2006). Diachea leucopodia (Bull.) Rostaf. First reported from Thailand by Siwasin and Ing (1982) and also listed by Tran et al. (2006, 2008). 7 Diachea radiata G. Lister et Petch First reported from Thailand by Reynolds and Alexopoulos (1971). Diachea splendens Peck First reported from Thailand by Tran et al. (2006, 2008). Diachea subsessilis Peck Not reported in print as occurring in Thailand but recorded from forest floor litter in a montane tropical forest on the grounds of the Mushroom Research Centre north of Chiang Mai (19º 34’ N, 99º 26’ E), 18 May 2007, TWKK 406. Diderma effusum (Schwein.) Morgan First reported from Thailand by Tran et al. (2006, 2008). Diderma hemisphaericum (Bull.) Hornem. First reported from Thailand by Tran et al. (2006, 2008). Diderma radiatum (L.) Morgan First reported from Thailand by Siwasin and Ing (1982). Diderma rimosum Eliasson & Nann.-Bremek. Not reported in print as occurring in Thailand but appearing in moist chamber culture on a sample of liana collected in a montane tropical forest, Mushroom Research Centre north of Chiang Mai (19º 34’ N, 99º 26’ E), TWKK 478. Our collection consists of only a few sporocarps, but these are characterized by a peridium falling away in plates, the most important distinguishing feature of Diderma rimosum. Diderma rugosum (Rex) T. Macbr. First reported from Thailand by Tran et al. (2006, 2008). Didymium anellus Morgan Not reported in print as occurring in Thailand but appearing in moist chamber culture on forest floor litter collected in a montane tropical forest, Lampang Water Fall near Lampang (19º 05’ N, 99º 43’ E), TWKK 425. Didymium bahiense Gottsb. 8 First reported from Thailand by Siwasin and Ing (1982) and also listed by Tran et al. (2008). Prior to the description of this species by Gottsberger and Nannenga-Bremekamp 1971), collections of Didymium bahiense would have been reported as D. iridis or possibly D. nigripes. Didymium clavus (Alb. et Schwein.) Rabenh. First reported from Thailand by Reynolds and Alexopoulos (1971) and also listed by Siwasin and Ing (1982) and Tran et al. (2006, 2008). Didymium difforme (Pers.) Gray First reported from Thailand by Tran et al. (2008). Didymium flexuosum Yamash. Not reported in print as occurring in Thailand but collected from forest floor litter in a montane tropical forest, Mushroom Research Centre north of Chiang Mai (19.1187 N, 98.7313 E), TWKK 494. Didymium iridis (Ditmar) Fr. First reported from Thailand by Reynolds and Alexopoulos (1971) and also listed by Tran et al. (2006, 2008). Didymium leoninum Berk. & Broome First reported from Thailand by Tran et al. (2006). Didymium minus (Lister) Morgan First reported from Thailand by Tran et al. (2006, 2008). This species is sometimes difficult to define, and some reports of Didymium minus in the literature probably represent atypical forms of D. nigripes or possibly even D. squamulosum. Didymium nigripes (Link) Fr. First reported from Thailand by Siwasin and Ing (1982) and also listed by Tran et al. (2006, 2008). Didymium ochroideum G. Lister Not reported in print as occurring in Thailand but appearing in moist chamber culture on a sample of aerial litter collected in a dry deciduous forest, Sakaerat Environmental Research Station, Nakorn Rachisima (14º 29’ N, 101º 55’ E), summer of 2004, SLS 21379. 9 Didymium squamulosum (Alb. & Schwein.) Fr. First reported from Thailand by Reynolds and Alexopoulos (1971) and also listed by Siwasin and Ing (1982), Ing et al. (1987) and Tran et al. (2006, 2008). Echinostelium minutum de Bary First reported from Thailand by Reynolds and Alexopoulos (1971) and more recently appearing in moist chamber culture on bark collected from an unidentified tree growing in a montane tropical forest, Mushroom Research Centre north of Chiang Mai (19º 34’ N, 99º 26’ E), DWM observed but not collected. Echinostelium minutum is exceedingly common in the bark microhabitat in temperate forests of the northern hemisphere, but the species seems to be rare in the same microhabitat of tropical forests such as those in Thailand. Fuligo aurea (Penz.) Y. Yamam. First reported from Thailand (as Erionema aureum Penz.) by Reynolds and Alexopoulos (1971). Fuligo septica (L.) F.H. Wigg. First reported from Thailand by Siwasin and Ing (1982) and also listed by Tran et al. (2006, 2008). Hemitrichia calyculata (Speg.) M.L. Farr First reported (as Hemitrichia stipata) from Thailand by Reynolds and Alexopoulos (1971) and also listed by Siwasin and Ing (1982), Ing et al. (1987) and Tran et al. (2006, 2008). Hemitrichia pardina (Minakata) Ing Not reported in print as occurring in Thailand but appearing in moist chamber culture on a sample of forest floor litter collected in a dry deciduous forest, Sakaerat Environmental Research Station, Nakorn Rachisima (14º 29’ N, 101º 55’ E), summer of 2004, SLS 19323. Hemitrichia serpula (Scop.) Rostaf. ex. Lister First reported from Thailand by Reynolds and Alexopoulos (1971) and also listed by Siwasin and Ing (1982) and Tran et al. (2006, 2008). Lamproderma scintillans (Berk. & Broome) Morgan 10 First reported from Thailand by Siwasin and Ing (1982) and also listed by Tran et al. (2006, 2008). Licea biforis Morgan First reported from Thailand by Reynolds and Alexopoulos (1971) and also listed by Tran et al. (2008). Licea bulbosa Nann.-Bremek. & Y. Yamam. Not reported in print as occurring in Thailand but appearing in a moist chamber culture prepared with bark from an unidentified tree, montane tropical forest on the grounds of the Mushroom Research Centre north of Chiang Mai (19º 34’ N, 99º 26’ E), 2008, DWM 7253. Our collection extends the known distribution of this species to southeast Asia. It appears to be rare, since no more than about a dozen collections are known worldwide (Wrigley de Basanta and Lado 2005). Licea erecta K.S.Thind & Dhillon First reported from Thailand by Reynolds and Alexopoulos (1971) and also listed by Tran et al. (2006). This species, described originally from Japan (Thind and Dhillon 1967, is known from fewer than half a dozen localities worldwide (Wrigley de Basanta and Lado 2005). These limited data suggest a distribution centered in the tropics, but our collection is the first from Southeast Asia. Licea floriformis T.N.Lakh. & R.K.Chopra Not reported in print as occurring in Thailand but appearing in moist chamber culture on the bark surface of pieces of an orchid root collected from the Bai Orchid Farm near Chiang Mai (18° 93' N, 98° 85' E) in 2007 (TWKK 435). Described originally from Europe, this is another rare species of Licea known from fewer than a dozen localities worldwide (Wrigley de Basanta and Lado 2005). Our collections are the first from Southeast Asia. Licea operculata (Wingate) G.W.Martin Not reported in print as occurring in Thailand but appearing in moist chamber culture on aerial litter collected from a premontane moist seasonal forest dominated by Quercus eumorpha in the Doi Inthanon complex (18°31'34" N and 98°29'44" E) in 2008 (CR 2117). Licea pedicellata (H.C. Gilbert) H.C. Gilbert Not reported in print as occurring in Thailand but appearing in moist chamber culture on pieces of a dead liana collected in a montane tropical forest in Doisuthep near Chiang Mai (18º 48’ N, 98º 55’ E), TWKK 580. 11 Lycogala epidendrum (L.) Fr. First reported from Thailand by Rostrup (1902) and also listed by Tran et al. (2006, 2008). Lycogala exiguum Morgan First reported from Thailand by Reynolds and Alexopoulos (1971) and also listed by Siwasin and Ing (1982) and Tran et al. (2006, 2008). Macbrideola cornea (G.Lister & Cran) Alexop. Not reported in print as occurring in Thailand but appearing in moist chamber culture on Pinus kesiya bark collected from a premontane moist seasonal forest dominated by the same pine tree in the Doi Inthanon complex (18°31'9" N and 98°31'4" E) in 2008 (CR 2125). Macbrideola scintillans H.C. Gilbert Not reported in print as occurring in Thailand but appearing in moist chamber culture on the bark of Lagerstroemia sp. in a montane tropical forest on the grounds of the Mushroom Research Centre north of Chiang Mai (19º 34’ N, 99º 26’ E), January 2008, DWM 7261. Perichaena chrysosperma (Curr.) Lister First reported from Thailand by Reynolds and Alexopoulos (1971) and also listed by Siwasin and Ing (1982) and Tran et al. (2008). Perichaena corticalis (Batsch) Rostaf. Not reported in print as occurring in Thailand but appearing in moist chamber culture on the bark of Juniperus sp., montane tropical forest near the summit of Doi Inthanon (18º 34’ N, 98º 29’ E), January 2008, DWM observed but not collected. Perichaena depressa Lib. First reported from Thailand by Tran et al. (2008). Perichaena dictyonema Rammeloo First reported from Thailand by Ko Ko et al. (2010). Perichaena microspora Penz. & Lister 12 First reported from Thailand by Tran et al. (2008). Perichaena pedata ((Lister & G.Lister) Lister ex E.Jahn First reported from Thailand by Tran et al. (2008). Perichaena quadrata T. Macbr. First reported from Thailand by Tran et al. (2008). Perichaena vermicularis (Schwein.) Rostaf. First reported from Thailand by Tran et al. (2008). Physarina echinocephala Höhn. First reported from Thailand by Reynolds and Alexopoulos (1971). Physarella oblonga (Berk. & M.A. Curtis) Morgan First reported from Thailand by Reynolds and Alexopoulos (1971) and also listed by Siwasin and Ing (1982), Ing et al. (1987) and Tran et al. (2006). Physarum aeneum (Lister) R. E. Fr. First reported from Thailand by Ko Ko et al. (2010). Physarum album (Bull.) Chevall First reported (as Physarum nutans Pers.) from Thailand by Reynolds and Alexopoulos (1971) and also listed by Siwasin and Ing (1982), Ing et al. (1987) and Tran et al. (2006, 2008). Physarum bivalve Pers. First reported from Thailand by Tran et al. (2006). Physarum bogoriense Racib. First reported from Thailand by Tran et al. (2006). Physarum cinereum (Batsch) Pers. First reported from Thailand by Tran et al. (2006, 2008). Physarum compressum Alb. & Schwein. 13 First reported from Thailand by Reynolds and Alexopoulos (1971) and also listed by Siwasin and Ing (1982) and Tran et al. (2006, 2008). Physarum crateriforme Petch First reported from Thailand by Tran et al. (2008). Physarum decipiens M.A. Curtis First reported from Thailand by Tran et al. (2008). Physarum didermoides (Pers.) Rostaf. First reported from Thailand by Ko Ko et al. (2010). Physarum echinosporum Lister. First reported from Thailand by Tran et al. (2008). Physarum flavicomum Berk. First reported from Thailand by Reynolds and Alexopoulos (1971) and also listed by Siwasin and Ing (1982), Ing et al. (1987) and Tran et al. (2006). Physarum galbeum Wingate First reported from Thailand by Tran et al. (2006, 2008). Physarum globuliferum (Bull.) Pers. First reported from Thailand by Tran et al. (2006). Physarum cf. gyrosum Rostaf. Not reported in print as occurring in Thailand but appearing in moist chamber culture on a sample of aerial litter collected in a tropical dry forest at the Sakaerat Environmental Research Centre, Nakorn Rachisiama (14º 29’ N, 101º 55’ E), sample collected August 2004, SLS 23574. Physarum hongkongense Chao H. Chung First reported from Thailand by Tran et al. (2006, 2008). Physarum lakhanpalii Nann.-Bremek, & Y. Yamam. 14 Not reported in print as occurring in Thailand but appearing in moist chamber culture on a bark sample collected from an unidentified tree in a montane tropical forest, Doi Inthanon National Park near Chiang Mai (18º 32’ N, 98º 33’ E) in 2007, TWKK 369. Physarum cf. lateritium (Berk. & Ravenel) Morgan First reported from Thailand by Tran et al. (2006). Physarum melleum (Berk. & Broome) Massee First reported from Thailand by Reynolds and Alexopoulos (1971) and also listed by Ing et al. (1987) and Tran et al. (2006, 2008). Physarum nucleatum Rex First reported from Thailand by Reynolds and Alexopoulos (1971) and also listed by Tran et al. (2008). Physarum oblatum T. Macbr. First reported from Thailand by Reynolds and Alexopoulos (1971) and also listed by Siwasin and Ing (1982), Ing et al. (1987) and Tran et al. (2007). Physarum penetrale Rex First reported from Thailand by Tran et al. (2006). Physarum pezizoideum (Jungh.) Pavill. & Lagarde First reported from Thailand by Siwasin and Ing (1982). Physarum pusillum (Berk. & M.A. Curtis) G. Lister First reported from Thailand by Tran et al. (2006, 2008). Physarum retisporum G.W.Martin, K.S.Thind & Rehill First reported from Thailand by Tran et al. (2008). Physarum rigidum (G. Lister) G. Lister First reported from Thailand by Reynolds and Alexopoulos (1971). Physarum roseum Berk. & Broome First reported from Thailand by Tran et al. (2006, 2008). 15 Physarum serpula Morgan First reported from Thailand by Tran et al. (2006, 2008). Physarum stellatum (Massee) G.W. Martin First reported from Thailand by Siwasin and Ing (1982) and also listed by Ing et al. (1987). Physarum straminipes Lister First reported from Thailand by Tran et al. (2008). Physarum superbum Hagelst. First reported from Thailand by Tran et al. (2008). Physarum tenerum Rex First reported from Thailand by Reynolds and Alexopoulos (1971) and also listed by Ing et al. (1987). Physarum viride (Bull.) Pers. First reported from Thailand by Reynolds and Alexopoulos (1971) and also listed by Ing et al. (1987) and Tran et al. (2006, 2008). Stemonaria longa (Peck) Nann.-Bremek., R. Sharma & Y. Yamam. First reported (as Comatricha longa Peck) from Thailand by Reynolds and Alexopoulos (1971). Stemonitis axifera (Bull.) T. Macbr. First reported from Thailand by Tran et al. (2006). Stemonitis flavogenita E. Jahn Not reported in print a occurring in Thailand but collected from decaying wood in a montane tropical forest, Tung Joaw Village, Chiang Mai (19º 08’ N, 99º 38’ E), 9 July 2007, TWKK 534. Stemonitis fusca Roth First reported from Thailand by Rostrup (1902) and also listed by Reynolds and 16 Alexopoulos (1971) and Tran et al. (2006). Stemonitis herbatica Peck First reported from Thailand by Reynolds and Alexopoulos (1971) and also listed by Siwasin and Ing (1982). Stemonitopsis cf. microspora (Lister) Nann.-Bremek. Not reported in print as occurring in Thailand but collected from forest floor litter in a montane tropical forest on the grounds of the Mushroom Research Centre (19.1187 N, 98.7313 E), 13 August 2008, TWKK 43 and 46. Our material is only provisionally referred to this species, since the spores are larger than given in published descriptions of what appears to be a rarely collected myxomycete. Stemonitis mussooriensis G.W.Martin, K.S.Thind & Sohi Not reported in print as occurring in Thailand but appearing in moist chamber culture on aerial litter collected from a premontane moist seasonal forest dominated by Pinus kesiya in the Doi Inthanon complex (18°31'9" N and 98°31'4" E) in 2008 (CR 2120). Stemonitis nigrescens Rex. First reported from Thailand by Tran et al. (2006, 2008). Stemonitis nigrescens is not always considered as distinct from S. fusca, but the former is appreciably smaller and tends to occur on litter instead of wood. The latter is the usual substrate for S. fusca. Stemonitis smithii T. Macbr. First reported from Thailand by Siwasin and Ing (1982) and also listed by Ing et al. (1987). Stemonitis splendens Rostaf. First reported from Thailand by Reynolds and Alexopoulos (1971) and also listed by Siwasin and Ing (1982) and Ing et al. (1987). Stemonitis cf. virginiensis Rex First reported from Thailand by Tran et al. (2006, 2008). Stemonitopsis aequalis (Peck) Y. Yamam. First reported from Thailand by Tran et al. (2008). Stemonitopsis gracilis (G. Lister) Nann.-Bremek. 17 First reported from Thailand by Siwasin and Ing (1982). Stemonitopsis typhina (F.H. Wigg.) Nann.-Bremek. First reported from Thailand by Reynolds and Alexopoulos (1971) and also listed by Ing et al. (1987). Symphytocarpus impexus Ing & Nann.-Bremek. Not reported in print as occurring in Thailand but collected on forest floor litter in a montane tropical forest on the Mushroom Research Centre north of Chiang Mai (19º 34’ N, 99º 26’ E), 26 September 2006, TWKK 163. Trichia affinis de Bary First reported from Thailand by Siwasin and Ing (1982). Trichia verrucosa Berk. First reported from Thailand by Siwasin and Ing (1982). Tubulifera microsperma (Berk. & M.A.Curtis) Lado First reported from Thailand by Siwasin and Ing (1982) and also listed by Tran et al. (2008). Lado (2001) listed this species as Tubulifera microsperma (Berk. & M.A. Curtis) Lado. . Willkommlangea reticulata (Alb. & Schwein.) Kuntze First reported from Thailand by Tran et al. (2008). Discussion The new records listed herein bring the total number of myxomycetes reported from or known to occur in Thailand to at least 132 species in 30 different genera. Several specimens obtained during the surveys we carried out consisted of very limited or possibly aberrant and thus were impossible to determine beyond genus. It is possible that these represent additional species, but there is no way to knowing if this is the case unless more material becomes available. However, the myxomycete biota of Thailand exceeds that of any country in Southeast Asia. We hope that this effort will prompt future studies to document more completely the myxomycete biotas of other neighboring countries in Southeast Asia. Two of the authors of this paper (Stephenson and Rojas) have been involved in studies of the myxomycetes of Costa Rica. Costa Rica (51,100 km2) is much smaller than Thailand (513,115 km2), but both countries occur in the tropics (Costa Rica is located between 8º 18 and 11º N, whereas Thailand occurs between 5º and 20º N). As a result of a more intensive collecting effort carried out over a longer period of time and involving much of the entire country, 213 species of myxomycetes have been recorded for Costa Rica (Rojas et al. unpublished data) from a total of approximately 5,000 specimens collected in the field or from moist chamber cultures. The 132 species now known from Thailand are based upon about 600 specimens. Interestingly, the taxonomic distribution of species represented in the biotas of Costa Rica and Thailand are remarkably similar (Table 1). 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