Morphology and phylogeny reveal two new species and host records of hyphomycetous fungi on Areca species from marine habitats in Thailand

The marine ecosystem is the largest on Earth, supporting a wide variety of organisms. Fungi in this environment are diverse and play promising ecological roles. This study investigated fungi on submerged, decaying plant materials of Areca species trapped between rocks in seawater in Prachuap Khiri Khan Province, Thailand.

Morphological and multi-gene phylogenetic analysis (LSU - ITS - tub 2 - SSU for Tetraploa, ITS - LSU - tub 2 - rpb 2 for Rosellinia, LSU - ITS - tef 1 - α- rpb 2 for Musicillium and LSU - ITS - act for Sarocladium) revealed two new species: Tetraploa maritima, characterized by the presence of a hilum and elongating appendages, and Rosellinia maritima, distinguished by a brown to black conidial-like structure composed of interwoven, irregular cells without distinct conidiophores produced in sterile conditions, unlike other Rosellinia asexual morphs.

Additionally, two new host records (Musicillium theobromae and Sarocladium gamsii) are documented, with detailed descriptions of their in vivo and in vitro morphologies. Detailed morphological descriptions and illustrations are provided. This study contributes to the understanding of fungal diversity in marine environments.