Fissidens fontanus (Bach.Pyl.) Steud. and allies: aquatic bryophytes of the Asir granite highlands (Arabian Peninsula)

Two aquatic bryophytes of Northern character, Fissidens fontanus and Leptodictyum riparium, are reported for the first time from the Arabian Peninsula. A synthesis based on new field observations and a review of the literature provides an overview of the aquatic bryoflora of the Peninsula. The five species forming this exceptional assemblage in Arabia are mapped. They are restricted to wadis (dry riverbed that flows only after rain) carved into granite bedrock that efficiently channel and concentrate rainfall runoff – particularly under the influence of the monsoon – into localized zones of persistent moisture. The conservation status of these species is briefly discussed.