Where and how many new additions to the liverwort flora of Vietnam may be found?

Abstract. The study of the liverwort and hornwort flora of Vietnam has received additional interest in recent years as many new records have been revealed. This raises the question of the number of new records that may possibly be found and where they should be located. Data on new liverwort occurrences within the last 55 years were summarized to identify whether the discovery ‘plateau’ has been reached. The bioclimates of the localities of the newest records were examined using canonical correspondence analysis (CCA) to determine whether there was any regularity in the distribution of the new records. Progress in liverwort flora knowledge has not reached a plateau; moreover, within recent years, the number of recorded species has grown quickly. The new records are located in mountainous areas, and climatic characteristics of localities are different from those of the dominant low elevations in the study area. At the current stage 573 taxa (568 species plus 5 varieties) are known in Vietnam. They belong to 105 genera of 46 families. Vietnam has recently become a flagship country in the study of liverwort diversity in Indochina, and the regularities found in the country may be applied to other countries in this macroregion. Higher numbers of recorded species than are now known may be found in all Indochina countries. Mountainous land areas possess the potential ability to harbor a high number of new records.