Pileomyces formosanus gen. et sp nov (Halosphaeriaceae, Ascomycota) from a rocky shore of Taiwan

In Taiwan, knowledge of marine fungi is fragmentary with recent studies documenting 69 species from mangrove habitats, of which 34 taxa were new records for the country. Marine fungi on trapped substrates from rocky shores of Taiwan are comparatively less known. In a fieldtrip to Yingkeshih (New Taipei City, northeastern Taiwan), a new fungus belonging to the Halosphaeriaceae was discovered. This fungus is characterized by dark-coloured ascomata, broadly clavate asci with an apical thickening, pore and retraction of plasmalemma, and ellipsoidal ascospores with a sheet-like appendage covering one end, which eventually detaches from the ascospore. This distinctive ascospore appendage morphology is unique in the Halosphaeriaceae and Pileomyces formosanus gen. et sp. nov. is introduced to accommodate this fungus. Pileomyces resembles Aniptodera and Phaeonectriella in the morphology of the ascus, and Tirisporella (T. beccariana) in gross morphology of the ascospore appendage, however, the appendage is attached to the ascospores at the apex in Tirisporella.