Volume 63, Issue 2 - Special issue: Marine mycology: recent progress and future challenges / Issue editors: Ka-Lai Pang, Zhu-Hua Luo and Gaëtan Burgaud

Growing interest in understanding the relevance of marine fungi to food webs, biogeochemical cycling, and biological patterns necessitates establishing a context for interpreting future findings. To help establish this context, we summarize the diversity of cultured and observed marine planktonic fungi from across the world. While exploring this diversity, we discovered that only half of the known marine fungal species have a publicly available DNA locus, which we hypothesize will likely hinder accurate high-throughput sequencing classification in the future, as it does currently. Still, we reprocessed >600 high-throughput datasets and analyzed 4.9 × 10 9 sequences (4.8 × 10 9 shotgun metagenomic reads and 1.0 × 10 8 amplicon sequences) and found that every fungal phylum is represented in the global marine planktonic mycobiome; however, this mycobiome is generally predominated by three phyla: the Ascomycota, Basidiomycota, and Chytridiomycota. We hypothesize that these three clades are the most abundant due to a combination of evolutionary histories, as well as physical processes that aid in their dispersal. We found that environments with atypical salinity regimes (>5 standard deviations from the global mean: Red Sea, Baltic Sea, sea ice) hosted higher proportions of the Chytridiomycota, relative to open oceans that are dominated by Dikarya. The Baltic Sea and Mediterranean Sea had the highest fungal richness of all areas explored. An analysis of similarity identified significant differences between oceanographic regions. There were no latitudinal gradients of marine fungal richness and diversity observed. As more high-throughput sequencing data become available, expanding the collection of reference loci and genomes will be essential to understanding the ecology of marine fungi.

Marine filamentous fungi have been little studied in Sweden, which is remarkable given the depth and width of mycological studies in the country since the time of Elias Fries. Seventy-four marine fungi are listed for Sweden based on historical records and recent collections, of which 16 are new records for the country. New records for the country are based on morphological identification of species mainly from marine wood, and most of them from the Swedish West Coast. In some instances, the identifications have been made by comparisons of sequences obtained from cultures with reference sequences in GenBank. Corollospora angusta , Corollospora filiformis , and Corollospora pulchella , previously known from tropical/subtropical areas, are recorded for the first time for Sweden. The arctic Havispora longyearbyensis was also found. Kalmusia longispora and Neocamarosporium calvescens were reported for the first time from marine habitats.

This paper documents six new saprobic marine fungi and one new genus based on morphology and multi-gene phylogenies. Three Dothideomycetes, and members of the Pleosporales, are introduced: Pseudomassariosphaeria triseptata sp. nov. was recognized as a mangrove species in Amniculicolaceae, and Salsuginea phoenicis sp. nov. was discovered as a second member of Salsugineaceae. A new genus Raghukumaria with Raghukumaria keshaphalae sp. nov., recovered from mangroves, is phylogenetically sister to Halomassarina and nests in the Trematosphaeriaceae. Three new species are referred to the Sordariomycetes: Coniochaeta marina (Coniochaetales, Coniochaetaceae) on driftwood; Fusicolla bharatavarshae (Hypocreales, Nectriaceae) is introduced with asexual and sexual morphs, on decayed mangrove wood of Avicennia marina ; and Fusarium sedimenticola (Hypocreales, Nectriaceae) is new to the Fusarium solani species complex (FSSC) from deep-sea sediment.

In this study, we investigated fungal diversity of six Mid-Oceanic Ridge sediment samples collected in the East Pacific and the South Indian Oceans by culture-dependent as well as culture-independent approaches. A total of 97 fungal isolates were cultured, belonging to 7 genera and 10 species, including Penicillium (2 species), Rhodotorula , Meyerozyma , Ophiocordyceps , Vishniacozyma , Aspergillus (3 species) and Phoma . Forty-six operational taxonomic units (OTUs) were identified from 933 clones selected from 12 clone libraries based on the internal transcribed spacers including 5.8S (ITS) and 18S rDNA. Two cultured fungi and 9 OTUs from the clone libraries showed similarities less than 97% with the existing sequences in GenBank, suggesting possible new fungal taxa. Most of the fungi belonged to the Ascomycota, to a lesser extent the Basidiomycota. Five fungal genera including Aspergillus , Rhodotorula , Ophiocordyceps , Phoma and Penicillium were recovered by both culture-dependent and culture-independent approaches. In addition to some common genera such as Aspergillus , Penicillium , Ophiocordyceps , Purpureocillium , Tolypocladium, Rhodotorula and Fusarium , some unique species were each found in the East Pacific and the South Indian Oceans. It is worth mentioning that Ophiocordyceps heteropoda was found at both oceans by culture-dependent and culture-independent approaches, although it was only previously reported from terrestrial habitats.

In recent years, the Arctic has become a hot spot for microbial research. However, fungal diversity in the Chukchi Sea (adjacent to the Arctic Ocean) is little known. The purpose of this study was to explore fungal diversity in sediments of the Chukchi Sea and the temperature adaptability of the cultured fungi. A total of 74 fungal strains were isolated from nine marine sediment samples collected from the Chukchi Sea. These fungi were identified based on morphological characteristics and sequence comparison of the internal transcribed spacers of the ribosomal DNA (ITS-rDNA) with the GenBank reference sequence database. Amongst these fungi, 61 strains belonged to the Ascomycota and 13 strains were affiliated with the Basidiomycota. The dominant genus was Penicillium . These fungal strains were cultured at 4°C, 10°C, and 25°C to determine their temperature adaptability. Most strains were able to grow at 4°C, and Thelebolus ellipsoideus was identified as a psychrophilic fungus. Our results revealed a high fungal diversity in marine sediments of the Chukchi Sea and found that some fungal species ( Penicillium chrysogenum , Eutypella scoparia , Alternaria alternata , Cladosporium tenuissimum , C. perangustum s and Thelebolus ellipsoideus ) isolated from these sediments were able to grow at 10°C and 4°C.