Thailand (Siam) is situated in the southeastern corner of Asia between the latitudes 6o-20o N and longitudes 98o-105o E, sharing borders on west and northwest by Myanmar (Burma), on northeast by Laos, on southeast by Kampuchea (Cambodia), and on south by Malaysia (Map 1). With an area of 514,000 square kilometers, Thailand exhibits a diverse landscape, ranging from sea level to 2,850 meters in elevation. The most conspicuous terrain features of Thailand include several high mountains, a lowland central plain dominated by the Chao Phraya River, and an undulating dry upland plateau bordered by the Mekong River. The climate is characterized by tropical monsoon system which reverses its cycle seasonably. This variability in topography and climate has produced a diverse vegetation that includes a large number of mosses, representing one of the richest moss floras in the tropical Asia.
The latest catalogue of Thai mosses was published by Tixier (1971) who enumerated 516 accepted species. Recently, Tan & Iwatsuki (1993) published a useful checklist of Indochinese mosses, including references of 563 Thai mosses. However, the later checklist was based on published literature without citing specimen data and locality information. Since Tixier's (1971) study, an updated specimen-based checklist of the mosses of Thailand has not been available for comparison. The present study attempts to compile an up-to-date and annotated specimen-based catalogue, including the distribution of all moss species known to present in Thailand by provincial occurrences on dotted maps.
