Marine fungi of the Baltic Sea

ABSTRACT Vast parts of the Baltic Sea have been mycologically neglected and are still awaiting exploration. Here we summarise earlier records of marine fungi from the Baltic, supplementing them with discoveries from fieldwork in Sweden in 2019. Although marine fungal diversity is clearly attenuated in the brackish water of the Baltic Sea, a substantial number has still been discovered. Here we list 77 species from the Baltic Sea, whereas after a critical assessment a further 18 species have been excluded as records of marine fungi. The species have mainly been identified by their morphological features, supplemented by DNA-based diagnostics. Most of the species have their main distributions in temperate areas of the Atlantic Ocean. Some of the Baltic species discovered here represent far disjunctions to tropical waters while only a very few are until now only recorded for the Baltic Sea. In this paper two species belong in Basidiomycota, while the most ascomyceteous speciose classes are Sordariomycetes (with 42 species) and Dothideomycetes (24). Halosphaeriaceae is the most speciose family in marine habitats, as also in the Baltic Sea, represented here by 29 species. Three species are new to Europe, and in addition 13 to the Baltic Sea and 13 to Sweden.


Introduction
The Baltic Sea covers an area of 405,000 km 2 , an area slightly larger than Germany and smaller than Sweden (Bernes 2005). It constitutes one of our planet's largest bodies of brackish water, second only to the somewhat larger Black Sea (436,400 km 2 ; https://www.ceoe.udel. edu/blacksea/geography/index.html). By contrast, however, the Black Sea is on average much deeper and has a much larger volume 550,000 km 3 versus 20,840 km 3 for the Baltic. Both seas receive a strong influx of freshwater and also display a great variation in surface water salinity. Salinity in both seas fluctuates seasonally, between years and in longer cycles, depending on irregular influx of salt water.
In the Baltic Sea, surface salinity varies between c. 3 ‰ in the northernmost parts to some 20 ‰ close to the Danish straits and Öresund (Figure 1; from Hordoir et al. 2019;Janssen et al. 1999). The salinity of the subsurface water is generally higher and this layer is kept isolated from the surface water by a halocline, although occasional weatherand season-induced rotations of the waterbodies occurs (Bernes 2005).
The Baltic is geologically a young sea that has vacillated between being a large freshwater lake, a moderately high salinity sea, and the present state as a big body of brackish water (Bernes 2005). Consequently, the colonisation of many marine organisms into the Baltic might be comparatively recent, since the latest lake-phase ending only some 8,000 years ago. The ending of the Littorina Sea, some 3,000 years ago also brought a reduction in salinity to the present phase of the Baltic, called the Limnea Sea, as a consequence of reduced influx of ocean water with the land lifting process making the sounds to the Kattegatt shallower. For colonisation of the Baltic Sea, aquatic organisms needed to adapt to a different salinity regimen insofar that freshwater organisms had to tolerate an increasing salinity level and species adapted to ocean salinity faced a decreasing salinity in the Baltic.
The Baltic Sea has a rather low biodiversity as compared to Kattegatt or Skagerack, and the ecosystems are fragile and under pressure from eutrophication and other environmental disturbances (Bernes 2005), which i.a. has led to the development of large areas of anoxic bottoms. The Baltic Sea ecosystems and associated ecological trends have been thoroughly studied, although the emphasis has been on animal and plant communities along with studies of the algal and cyanobacterial blooms that heavily affect Baltic Sea ecology almost every summer (Bernes 2005). The precarious situation for many fish populations and lately also on the occurrences and effects of invasive species have been other major concerns.

Tools for assessing marine fungal diversity
Recently, the diversity of cultured and observed marine planktonic fungi from across the world was summarised in a review by Hassett et al. (2019), where it was noted that the Baltic and the Mediterranean Seas have the highest fungal diversity of all areas explored. Not surprisingly, the review revealed that only half of the known marine fungal species have an available DNA locus in public databases, a circumstance that is likely to be an obstacle to accurate high-throughput sequencing classification in the future, as it certainly is already at present. Naming and describing new taxa, sequencing DNA loci/ genes, has a fundamental role in marine environmental research. For marine fungi, the webpage http://www.marinefungi.org provides a search facility to genera of marine fungi, key to species and illustrations, updated information on such aspects as classification, full species descriptions, and listing of recent publications (Jones et al. 2019b). Such databases serve the scientific community in exploiting the diversity and quality of marine resources and to further research on marine fungi. In addition, as high-throughput sequencing data become more in use and available, expanding the collection of reference loci/genes and genomes will be fundamental in understanding the ecology of marine fungi.

Baltic marine mycology
The occurrence of marine fungi in the Baltic was discovered quite late and dates back to the late 19th century (Rostrup 1884(Rostrup , 1888. In the wake of an increased awareness of the ecological importance and taxonomic diversity of marine fungi, more detailed investigations of the marine fungi of the Baltic Sea were undertaken during the 20th century. Höhnk (1956aHöhnk ( , 1956b) studies the aquatic fungi from the Baltic Sea, and although mainly targeting various ecological questions (i.a. chartering salinity tolerance), a number of filamentous species were recorded in his papers, of which some were described as new. For many of the records (e.g. in Höhnk 1955), it is not possible to trace the precise locality and often materials from both the Baltic and the Atlantic were dealt with in the same paper. The thesis of Schmidt (1974a) summarised the results of a comprehensive inventory of the marine fungi of the Baltic coastline of Mecklenburg (Germany). Parts of this work had been published earlier (Schmidt 1967(Schmidt , 1969a(Schmidt , 1969b. During her research Schmidt described several new taxa that subsequently have been accepted and often found to have a wider distribution outside of the Baltic Sea. Schmidt (1974b) further investigated the distribution of marine fungi along part of the Baltic coast and noted patterns of distribution in relation to salinity zones and suggested distinctions between obligate and facultative marine species. Initially, exploration of low-salinity tolerance was surveyed when little was known about the total distribution of marine fungi (Höhnk 1956b;Schmidt 1974b). Now this knowledge is much more comprehensive and we will here try to give attention to the world-wide distribution of the species found in the Baltic Sea. There has been much nomenclatural turbulence for the marine fungi, particularly since molecular data have assumed an increasingly important part in clarifying their phylogeny and the ensuing revisions of their classification and nomenclature ). Here we have tried to accustom the names to the more recent findings.
The aim of this paper is to update knowledge on the occurrence of marine fungal species in the Baltic. The treatment concentrates on ascomycetous and basidiomycetous filamentous fungi, thus leaving other ecologically very important groups of fungi, like Chytridiomycota and yeasts, unaccounted for. The species included are those that in some respect seem to have a consistent association with saline water. They are often found on driftwood, on macroalgae, and on shore plantsliving or dead. Several have been recovered (particularly by Schmidt 1974a) on bait panels or wooden constructions along the shore-line. These habitats have been described as "marine wood" below.

Material and methods
New and additional records in this paper originate from eight localities on Gotland, one in Södermanland, and two in Uppland in Sweden (for provinces see http:// mapsof.net/sweden/provinces-ofsweden). This material was collected from driftwood and shore plant remains. Substrates detailed in the list of species are based on Baltic material. Cultures were obtained by squashing fungal fruiting bodies from wood in seawater and spreading onto Potato Dextrose Agar (Sigma-Aldrich, USA) plates with seawater amended with Kanamycin A. The mycelial cultures obtained after incubation for 4-16 weeks were used for DNA isolation. The DNeasy Plant Mini Kit (Qiagen, Hillden, Germany) was used for isolating total DNA following the instructions of the manufacturer. Diluted (1:10) or undiluted DNA (3 μl) was used for PCR amplifications which also included the AccuPower® PCR PreMix (Bioneer, Daejeon, Republic of Korea), by adding 1.5 μl of each primer (10 μm) and water to a total volume of 20 μl. Primers used to amplify the ITS locus: ITS1 f (Gardes and Bruns 1993) and ITS 4 (White et al. 1990). Thermal cycling parameters were: initial denaturation for 4 min at 95°C, followed by 35 cycles of 1 min at 94°C, 1 min at 54°C, 45 s at 72°C, and final elongation for 5 min at 72°C. Amplification products were visualised on 0.5% agarose gels stained with gel red and the PCR product was purified using the Illustra™ ExoStar buffer diluted 10×, following the manufacturer's protocol. Sequencing, automated reaction clean up, and visualisation were carried out as described by Macrogen Inc., Korea (www.macrogen.com). The UNITE database was queried with generated ITS sequences to infer taxonomy through molecular identification (https:// unite.ut.ee/; Nilsson et al. 2018). Newly produced sequences have been deposited in GenBank.

Diversity and ecology of Baltic marine fungi
In the following, historical records of marine fungi from the Baltic are summarised but have been included only when the locality has been unequivocally identified. Recent discoveries result from our field-work on Gotland (E.B.G. Jones, S. Tibell, and L. Tibell) and in the Swedish provinces of Södermanland and Uppland (K.-L. Pang, S. Tibell, and L. Tibell) in 2019. The distributions of the species in the Baltic Sea in the following list have been described under "Distribution", whereas comments on the total distribution of the species sometimes has been included under "Notes". Distribution: Germany. Mecklenburg-Vorpommern, Gross-Schwansee (Schmidt 1974a, as Camarosporium metableticum). Note. Recorded by Schmidt (1974a) as an obligate marine species occurring in the mesohaline zone. Also recorded from temperate coastal areas of the Atlantic and Pacific Oceans. A species frequently collected on Ammophila arenaria.

Distribution:
Denmark. Sjaelland. Sweden. Ångermanland, Öland, Västerbotten. New record: Sweden. Gotland, Ardre par., Folhammar, 57°20ʹ45.03"N, 18°43ʹ59.11"E. Note. Reported from Denmark by Rostrup (1884Rostrup ( , 1888, Rees et al. (1979) made 64 collections on wood associated with sand in N. Jutland, Koch and Jones (1983) on wood from Nakkehoved fyr, and from Sweden by Henningsson (1974: Ångermanland, Öland) and Eriksson (2014: Västerbotten). A halophilous species, known from many areas in temperate to cold areas of the Atlantic and Pacific Oceans, particularly from localities influenced by freshwater (Koch 1974 Note. An oceanic species with a distribution in tropical to temperate areas of the Atlantic, Indian, and Pacific Oceans (Kohlmeyer and Kohlmeyer 1979). New to the East Coast of Sweden and new to Södermanland.

Asteromyces cruciatus C. Moreau and Moreau ex Hennebert
Substrate: Decaying Fucus vesiculosus and Laminaria saccharina. An arenicolous species frequently isolated from sand and wood associated with sand. Distribution: Germany. Mecklenburg-Vorpommern, Gross-Schwansee (Schmidt 1974b, as Camarosporium metableticum). Note. Recorded by Schmidt (1974a) as an obligate marine species occurring in the mesohaline zone. Also known from Denmark, N Jutland, isolated from wood from surface layer to a depth of 30 mm (total isolations 23, Rees et al. 1979) and many collections from sites in Jutland (Koch and Jones 1983). An oceanic species with a distribution in tropical to temperate areas of the Atlantic, Indian, and Pacific. A halophilous species.  (Schmidt 1967).
Note. Originally described from water of rather low salinity in the Baltic Sea, this species has also been reported from Hawaii. Also known from Denmark, Vigsǿ (Koch and Jones 1983); 19 collections from wood in association with sand at Blokhus, and Lǿkken, Jutland (Rees and Jones 1985). A common species at various world locations. A halophilous species.
Note. This species was described from water of rather low salinity in the Baltic, and no additional records have been published. Jones EBG has collected it twice at Grǿnhǿj, Jutland, Denmark and considered it to be a rare species on wood associated with sand (unpublished). A halophilous species.

Ceriosporopsis halima Linder
Substrate: Marine wood. Distribution: Denmark. Sjaelland, Copenhagen, Charlottenlund (Höhnk 1955, as C. barbata). Germany. Mecklenburg-Vorpommern, Barther Oie, Binzer Bucht, Bock, Stralsund, Prerow (Schmidt 1967(Schmidt , 1974a(Schmidt , 1974b. Sweden. Öland, Uppland (Henningsson 1974). Note. Recorded by Schmidt (1974b) as an obligate marine species occurring in the mesohaline zone. Also known from Denmark, two collections from wood in association with sand at Blokhus, and Lǿkken, Jutland (Rees and Jones 1985). Originally described from the USA, it has been shown to have a distribution in coastal areas of both the western and eastern North Atlantic. It has also been recorded from the Indian and the Pacific Oceans. An early coloniser of wood submerged in the sea.

Cirrenalia macrocephala (Kohlm.) Meyers and R.T. Moore
Substrate: Marine wood. Distribution: Germany, Mecklenburg-Vorpommern, several localities (Schmidt 1967(Schmidt , 1974a(Schmidt , 1974b. Note. Recorded by Schmidt (1974aSchmidt ( , 1974b) as an obligate marine species occurring in the meso-to oligohaline zones. It is distributed in temperate to warm coastal waters of the eastern and western North Atlantic and the eastern Pacific north of the equator. Collected by Jones and Koch in Vedbaek, Denmark and at Blokhus, and Lǿkken, Jutland (Rees and Jones 1985). A halophilous species.  ) and also known from Uppland. A halophilous species. New to Gotland and Södermanland. So far only known from the Baltic Sea and the Swedish West Coast. A collection from Sweden, Bohuslän. Skaftö par., Fiskebäckskil, Rödbergsviken, 58º15´08´´; 11º27 58´´, was collected on a large piece of driftwood by L. Tibell, June 2017, GJ 396 (MFLU 19-1240. Two recently described Conichaeta species have been introduced from marine habitats: C. krabiensis on wood from Thailand, and C. arenariae on Ammophila arenaria in Wales (Dayarathne et al. 2020).
Note. This oceanic species was originally described from Japan and has also been recorded from the Eastern and Western Pacific Oceans. New to the Baltic Sea and Sweden.
16. Corollospora pulchella Kohlm., I. Schmidt and N.B. Nair Substrate: Remains of Fucus vesiculosus. Distribution: Germany, Mecklenburg-Vorpommern, Strelasund (Kohlmeyer et al. 1967); Altefähr, Grosse Schwansee, Lohme, Wissower Klinken (Schmidt 1974b). Note. Originally described from India and recorded from the Baltic Sea by Schmidt (1974b) as an obligate marine species occurring in the mesohaline zone. Also recorded from Denmark by Koch (1974) and Koch and Jones (1983). An oceanic species with a distribution in temperate to tropical areas that has subsequently also been recorded from the southwestern North Atlantic and the Pacific Oceans.

Crinigera maritima I. Schmidt
Substrate: Decaying thalli of Fucus vesiculosus and marine wood. Distribution: Germany, Mecklenburg-Vorpommern, Binzer Bucht, Glowe, Gross-Schwansee (Schmidt 1974). Note. Described from the Baltic Sea, Crinigera maritima was introduced by Schmidt on Fucus vesiculosus and marine wood but upon reinvestigation of the type material it was found to comprise two separate fungi (Koch and Jones 1989). The material on wood was designated a new genus and species Dryosphaera (D. navigans) and the material on the seaweed referred to Crinigera maritima. Recorded by Schmidt (1974) as an obligate marine species occurring in the mesohaline zone. Crinigera maritima specimens collected prior to 1989 need to be sequenced, re-evaluated, and correctly identified.

Cumulospora marina I. Schmidt
Substrate: Marine wood, Phragmites, and other plant remains. Distribution: Germany, Mecklenburg-Vorpommern, Barther Oie, Kloster (Hiddensee) Seeseite, Kubitzer Bodden, Schaprode, Stralsund (Schmidt 1974, as Vesicularia marina). Note. Originally described from the Baltic Sea as Vesicularia marina Schmidt (1974), but as this name was preoccupied, the new name Cumulospora was proposed (Schmidt 1985). The same fungus was also described by Abdullah et al. (1989) Schmidt (1974) as an obligate marine species occurring in the meso-to oligohaline zones. Many collections recorded from various locations in Denmark (Rees et al. 1979;Koch and Jones 1983). An oceanic species distributed in temperate waters of the Atlantic and Pacific oceans.
Note. An oceanic species known from various localities of the temperate parts of the Atlantic and Pacific coasts (Kohlmeyer and Kohlmeyer 1979). Reported by Koch and Jones (1983) from Denmark and easily missed by its white resupinate fruit body.  (Artemczuk 1980), this might be a species confined to brackish water. New to the Baltic Sea, and Sweden.

Haligena elaterophora Kohlm.
Substrate: Marine wood. Distribution: Sweden. Medelpad, Södermanland and Uppland (Henningsson 1974). Note. Recorded by Schmidt (1974) as an obligate marine species occurring in the mesohaline zone. Reported by Rees et al. (1979) and Koch and Jones (1983) from various localities in Denmark. An oceanic species which has also been recorded from temperate coastal areas of the North Atlantic and the eastern Pacific Ocean.

Additional records
Gotland. Fårö par., Ekeviken, 57°58ʹ30.28"N, 19°1 5ʹ24.69"E, ST19-31 (UPS), ST19-103 (UPS), ST19-115 (UPS), ST19-119 (UPS). Note. Described from Australia, it was recorded by Schmidt (1974) as an obligate marine species occurring in the meso-to oligohaline zones. An oceanic species with a distribution in tropical to temperate parts of the Atlantic, Indian, and Pacific Oceans. Rees et al. (1979) documented 23 collections on wood associated with sand from Blokhus, and Lǿkken, Jutland, Denmark. Also reported from Denmark by Koch (1974) and Koch and Jones (1983). The records from Södermanland and Uppland indicate a considerable tolerance to low salinity levels, hence here considered an euryhaline species. New to Gotland.  (Schmidt 1969(Schmidt -1985 as Cirrenalia fusca). Note. Originally described from the Baltic Sea. Recorded by Schmidt (1974a;1974b; C. fusca) as an obligate marine species occurring in the meso-to oligohaline zones. It has subsequently been recorded also from France and Japan (Abdel-Wahab et al. 2010 Schmidt (1974) as an obligate marine species occurring in the mesohaline zone. Known from temperate parts of both the East and West Coasts of the North Atlantic Ocean. Also recorded on wood associated with sand from Blokhus, and Lǿkken, Jutland, Denmark (Rees and Jones 1985).

Halosphaeria appendiculata Linder
Substrate: Marine wood. Distribution: Germany. Mecklenburg-Vorpommern, Binzer Bucht, Glowe, Karlshagen (Schmidt 1974). Note. Recorded by Schmidt (1974) as an obligate marine species occurring in the mesohaline zone. Many records for Denmark (Koch 1974;Koch and Jones 1983). An oceanic species with distribution in subtropical to temperate areas of the Atlantic and Pacific Oceans.
34. Remispora hamata (Höhnk) Kohlm. (Figure 3(c)) Substrate: Marine wood and Phragmites. Distribution: Germany. Mecklenburg-Vorpommern, Glowe, Karlshagen, Prohner Bach (Schmidt 1974). Note. Recorded by Schmidt (1974) as an obligate marine species occurring in the meso-to oligohaline zones. An oceanic species with distribution in subtropical to temperate areas of the Atlantic and Pacific Oceans. This species was not recognised as a valid species by Jones et al. (2015) but our preliminary phylogenetic analysis of its 28 S rDNA suggests that this is a valid species but its taxonomic position remains to be determined (unpublished results). Note. Originally described from the German North Sea coast, it was recorded by Schmidt (1974) as an obligate marine species occurring in the meso-to oligohaline zones. An oceanic species spread in tropical to temperate waters in both hemispheres, and occurs in the Atlantic, Indian, and Pacific Oceans.

Naïs inornata Kohlm.
Substrate: Marine wood. Distribution: Germany. Mecklenburg-Vorpommern, Barther Oie, Kloster Boddensetie, Grosse Jasmunder Bodden, Stralsund (Schmidt 1974). Note. Recorded by Schmidt (1974aSchmidt ( , 1974b) as an obligate marine species occurring in the meso-to oligohaline zones. Rees et al. (1979) record 44 collections on wood associated with sand from Blokhus, and Lǿkken, Jutland, Denmark. An oceanic species with a distribution in coastal, temperate areas of both the eastern and western North Atlantic and the Pacific Ocean. Note. This collection was identified as the asexual morph of Lentithecium lineare by sequence data and is illustrated in Figure 2. This is the first time an asexual morph has been described for this species. Lentithecium species are reported from both freshwater and marine habitats with L. rarum and L. voraginesporum listed in Jones et al. (2019), see website http://www.marinefungi.org. A new Lentithecium species will be described in follow-up paper. Note. Originally described from Scotland, this species is known from Phragmites culms in Northwestern Europe. It was reported from the province of Skåne by Eriksson (2014) Jones et al. (2019b). This is a little known ascomycete in the Pseudoperisporiaceae, and historically referred to many other genera including Lizoniella, Mycosphaerella, and Sphaerulina. Genus accepted in Hyde et al. (2013) (Henningsson 1974), Södermanland (Henningsson 1974). Notes. Zalerion maritima was connected culturally and phylogenetically with the sexual morph Lulwoana uniseptata by Nakagiri (1984) and Campbell et al. (2005), respectively. Recorded by Schmidt (1974, as Z. maritimum) as an obligate marine species occurring in the mesohaline zone. Originally the sexual morph was described from Japan, this oceanic species is now known to have a distribution in the subtropical to temperate Eastern Pacific, and in the Eastern North Atlantic Oceans.
Note. An oceanic species originally described from England on the brown seaweed Fucus, but reported and isolated from intertidal wood in Chile by Burgos and Shearer (1977) epitypified by Campbell (2005). Found also on Spartina culms in England (Jones, unpublished Note. An oceanic species originally described from the Atlantic coast of North America, but distributed in coastal, temperate parts of the eastern North Atlantic Ocean and also found in the eastern Pacific Ocean.  Distribution: Germany. Mecklenburg-Vorpommern, Stralsund (Schmidt 1974, as Haligena spartinae). Sweden. Uppland (Henningsson 1974 as Haligena spartinae). Note. Only recorded from a locality with very low salinity by Schmidt (1974b). Originally described from Britain, but has also been reported from the east coast of the USA. A halophilous species.  (Schmidt 1974). Sweden. Ångermanland, Södermanland, Uppland (Henningsson 1974, as Corollospora comata). Note. Recorded by Schmidt (1974) as an obligate marine species occurring in the mesohaline zone. Originally described from the USA, this species has been recorded from coastal temperate areas of both the eastern and western parts of the North Atlantic Ocean. Note. Recorded by Schmidt (1974) as an obligate marine species occurring in the mesohaline zone. An oceanic species recorded from temperate parts of the eastern North Atlantic Ocean. Often reported as the asexual morph Monodictys pelagica (Mouzouras and Jones 1985).

Pseudogymnoascus roseus Raillo
Substrate: Marine wood. Distribution: Sweden. Öland (Henningsson 1974). Note. A species originally described from soil but also associated with wood (Rice and Currah 2006), seems not otherwise to have been recorded from marine wood.
Substrate: Marine wood. Distribution: Denmark. Sjaelland, Copenhagen (Höhnk 1955 as Palomyces quadri-remis Höhnk), also reported by Koch and Jones 1983). Germany. Mecklenburg-Vorpommern, numerous localities (Schmidt 1974a(Schmidt , 1974b as Halosphaeria quadriremis). Sweden. Ångermanland (Henningsson 1974 as Halosphaeria quadri-remis). Note. Recorded by Schmidt (1974) as an obligate marine species occurring in the mesohaline zone. Originally described from the German Atlantic coast it is now known to be distributed in temperate to warm coastal waters of the eastern and western North Atlantic Ocean.  Schmidt (1974b) as an obligate marine species occurring in the meso-to oligohaline zones. Rees et al. (1979) listed 30 collections on wood associated with sand from Blokhus, and Lǿkken, Jutland, Denmark. Originally described from the USA, this species has also been recorded from temperate areas of the eastern North Atlantic Ocean. Note. Originally described from Florida as Nais glitra, this species was reported from tropical locations (Jones and Pang 2012). Referred to Saagaromyces based on sequence data and unusual for the genus in lacking appendages (Pang et al. 2003 Note. The type material of this species was described from culms of Phragmites australis collected at Mai Po mangrove, Hong Kong, but whether the type was of a marine origin is unknown (Quaedvlieg et al. 2013). The water of the sandy beach at Askö, where this fungus was collected, is brackish. New to the Baltic Sea, and Sweden.
Note. Originally described from the USA, this species has a distribution in both the eastern and western North Atlantic Ocean. Further it has been recorded from the Pacific Ocean (California and Hawaii). Also reported from Spartina species (Jones 1963;Calado et al. 2015 Schmidt (1974b) as an obligate marine species occurring in the meso-to oligohaline zones. Rees et al. (1979) isolated it at various depths in sand collected in Denmark and on wood baits. Originally described from North America, it has been shown to have a distribution in tropical to temperate areas of the Atlantic, Indian, and Pacific Oceans.

77.
Trichocladium melhae E.B.G. Jones, Abdel-Wahab, and Vrijmoed Substrate: Driftwood. New record: Sweden. Gotland. Ekeviken, 03/07/2019. Note. Originally described from Hong-Kong (Jones et al. 2001), and also known from India, Japan, Malaysia, and Singapore, it was described as a tropical species. The disjunction to the Baltic Sea seems quite dramatic, but may probably just reflect the insufficient exploration of marine fungi at large. New to Europe, the Baltic Sea, and to Sweden.

Discussion
The title of this paper includes the concept "marine fungi", a concept that has been greatly discussed during the history of marine mycology. The recognition of "marine fungi" is particularly challenging in brackish waters, and its use might be claimed to be inappropriate or uninteresting. The distinction made here is based on the total distribution of each species. If a species has only been reported from oceanic waters, or clearly in most cases been found in the oceans (apart from in the Baltic Sea) it qualifies as marine. These assessments have also in part rested on the information in Schmidt (1974), where the occurrences of species in different salinity zones were indicated. After these elaborations and critical evaluation of earlier records, 77 species have been listed as marine and occurring in the Baltic Sea. These records encompass both records from the literature (first and foremost those of Höhnk, Henningson and Schmidt) and in addition several new discoveries from our field-work in the provinces of Gotland, and the Baltic shores of Södermanland and Uppland in Sweden. Most of the records were identified by their morphology, some by the sequencing of their nuITS, in which cases GenBank numbers have been provided (see also Supplement 1). In addition to this, 18 species for reasons of nomenclatural deficiencies and/or unclear ecological preferences were excluded from the main list of marine fungi, including one new species for Sweden (not included in the main text, see Supplement 1). Several of these records are early and for various reasons hard to verify; others refer to terrestrial species considered of accidental or facultative occurrence in the Baltic.
The total distribution of each species has been briefly outlined, and most of the Baltic marine species have their main distribution in temperate waters of the Atlantic Ocean. Corollospora luteola, Halojulella avicenniae, and Trichocladium melhae are here recorded for the first time from Europe. Additionally Corollospora gracilis, C. quinqueseptata, Diplodia thalassia, Emericellopsis maritima, Leptosphaeria australiensis, Paradendryphiella arenariae, Paraphaeosphaeria sporulosa, and Setoseptoria phragmitis are for the first time reported from the Baltic Sea and Sweden. Lautisporopsis circumvestita and Diplodia orae-maris are new just for the Baltic Sea, while Leptosphaeria albopunctata and Trichocladium lignicola are new just to Sweden.
Interestingly some of the Baltic marine fungi, like Halojulella avicenniae, Leptosphaeria australis, Setoseptoria phragmitis, and Trichocladium melhae exhibit rather dramatic disjunctions to faraway tropical areas. Diplodia thalassia and Emericellopsis maritima have been described from the Black Sea and might be species confined to brackish waters. Two species, Trichocladium constrictum and T. lignicola, are presently only known from the Baltic Sea.
In conclusion, among the 77 species recorded only two belong in Basidiomycota, viz. Digitatispora marina and Leucosporidium scottii, while the vast majority belong to the Ascomycota. The most ascomyceteous speciose classes are Sordariomycetes (42) with most species in Microascales (29), Lulworthiales (6), and Sordariales (5); and Dothideomycetes (24) with Pleosporales (19) been the most speciose. In a metabarcoding study by Rojas-Jimenez et al. (2019), other phyla of fungi have also been recovered as sequences from the Baltic Sea including the Chytridiomycota (orders Rhizophydiales, Lobulomycetales, and Gromochytriales) and the Cryptomycota. Halosphaeriaceae is the family usually dominating in marine oceanic habitats, and the Baltic Sea (29). While many families are reported by one to two species, Chaetomiaceae (5), Leptosphaeriaceae (3), Lulworthiaceae (5), Phaeosphaeriaceae (3), and Pleosporaceae (5) harbour a few species. Corollospora, with six species, is the most species-rich genus in the Baltic.