Hymenostylium hildebrandtii (C.!Mull.) Zander (Pottiaceae, Musci), and further new and interesting records to the moss flora of Yemen and Socotra -: Studies in Arabian bryophytes 22

New bryophyte collections on the island of Socotra and in the Yemen highland revealed 6 mosses new to the bryophyte flora of Yemen. Outstanding among these records are Fissidens serratus C. Mull. (Socotra) and Hymenostylium hildebrandtii (C. Mull.) Zander (Yemen escarpment mountains), indicating again the tropical influence and character of the southwestern Arabian Peninsula and Socotra. Whereas Hymenosytlium hildebrandtii belongs to a xero-tropical Paleoafrican element, and was formerly known only from Somalia, the paleotropical Fissidens serratus is widely distributed in Southeast Asia. It represents a further Indo-Malayan species which links southern Arabia and Southeast Asia.