Aphyllophoroid funga (Basidiomycota) of Finland: range extensions and records of nationally new and rare species

Knowledge of the Finnish aphyllophoroid funga has increased substantially in recent years. In this article, we present two species new to Finland: Spiculogloea subminuta Hauerslev and Typhula suecica I. Olariaga, G. Corriol, I. Salcedo & K. Hansen, and document Sistotrema luteoviride Kotir. & K.-H. Larss. for the third time globally. We also contribute 50 new records of 33 nationally rare species (with a maximum of ten previous records in Finland) and list 52 regionally new species, found for the first time in a certain subzone of the boreal vegetation zone in Finland. Each record is enclosed and contains notes on the substrate. Furthermore, the ecology of the nationally new species and the distribution of rare species are discussed.


Introduction
Aphyllophoroid fungi are an ecological and morphological form group of the Basidiomycota, which consists of morphologically varied fungal subgroups, such as corticioids, polypores, clavarioids, and tremelloids. These groups are highly taxonomically diverse and polyphyletic [1]. Aphyllophoroid fungi consist of wood decay fungi, litter decay fungi, ectomycorrhizal species, parasitic fungi, and mycoparasites [2].
However, the occurrence and distribution of many aphyllophoroid species in Finland are still not adequately known; therefore, there are large gaps in the knowledge of their ecology, biogeography, substrata, and habitat requirements and their conservation status and accurate threat levels are difficult to evaluate. The main reasons for this

Results: list of species
Two of the presented species are new to Finland: Spiculogloea subminuta Hauerslev and Typhula suecica I. Olariaga, G. Corriol, I. Salcedo & K. Hansen. The discovery of Sistotrema luteoviride is the third recorded globally, with all records being from Finland. We present 50 new records (localities) of the following 33 rare or infrequently collected species (a maximum of ten previous records in Finland) and the ordinal number of these records in Finland is provided in Tab. 1

Tulasnella thelephorea 6th
Xenasma rimicola 3rd-4th    [3,7].       New to Southern Boreal, Lake District (2b), and Middle Boreal, Northern Carelia -Kainuu (3b). These are the third and fourth records of the species in Finland; previous records were from Salo (1b) and Lammi (2a) [2,8]. Endangered.        The trunks were mainly dead, and the fallen branches were 1-5 cm in diameter where the basidiomata were found. All shrubs grew on a stony sea shore, with two findings made in a shore meadow ca. 50 meters away from the H. rhamnoides stands and substrata with broken pieces of trunk (diam. 7 and 10 cm, Decay Stage 4).

Species new to Finland
Spiculogloea subminuta was described based on a single collection in Denmark [30], with Botryobasidium subcoronatum (Höhn. & Litsch.) Donk as the host species. Rödel [31] made several records of S. subminuta from Germany; in all the cases, the host species was B. subcoronatum. In Norway and Sweden, the host species was Botryobasidium intertextum, which grew on Picea abies [32]. The first Finnish record was from a very old, pristine or near-pristine, spruce-dominated mesic heath forest inside the Ulvilansalo strict nature reserve, on a fallen Picea abies trunk. The second Finnish record was found on a fallen Pinus sylvestris trunk in a pine-dominated, middle-aged, xeric heath forest with a forestry history and a low level of dead wood, even though there was some decaying kelo-wood at the landscape level. The basidiomata were found in B. subcoronatum. Spiculogloea subminuta is likely not as rare as the current records show; however, basidiomata are very small and grow inside other fungi, so are easily overlooked when the host species has already been identified. Both B. intertextum and B. subcoronatum are common species in Finland [2] and although S. subminuta is abundant and macroscopically quite conspicuous, it can be mistakenly identified as a conidial state of the host. This may help with identification since anamorphs of B. subcoronatum or B. intertextum have not yet been reported [19,33]. More records are required to further evaluate its distribution and ecological requirements. Typhula suecica is widely distributed, but rare [34], and grows in damp forests on the dead, fallen leaves of Acer, Alnus, and Populus. Olariaga et al. [34] reported T. suecica in Southern France, Spain (Pyrenees), and central Sweden. Its Finnish localities (very close together) are in the southeastern corner of Finland on the shore of the Finnish Gulf in damp forests in which the fungus grew on the dead leaves of Alnus and Populus. The wide distribution area and "trivial" habitats connected with common substrata give the impression that T. suecica is not a threatened species in Europe, even if it is seldom collected.

Significant extensions of known distribution
Many of the new regional records occurred far away from their previously known localities, especially in eastern and northern Finland. This is mainly explained by the fact that areas, habitats, and substrata that had been little studied or overlooked are now being surveyed.
The habitats of Fuscoporia contigua (i.e., coastal scrub of common sea buckthorn, Hippophaë rhamnoides) have not been surveyed by mycologists, so it seems to appear that the lack of observations is mainly due to a lack of studies. The species has now been found 185 km northeast of Eckerö (1a), and it is likely that the species also occurs between these two locations, since suitable habitats exist widely. According to our understanding, F. contigua could occur if old shrubs and large stands of common sea buckthorn and their continuum are available. In this study, F. contigua was found in sites where coastal scrubs of common sea buckthorn are exposed to moving ice floes and the waves of ship traffic. This damages shrubs and creates suitable areas for growth on their trunks. Occurrences in Pori have now been found at three locations close to one other, within a distance of five kilometers. There are tens of records of F. contigua in Sweden (http://www.artportalen.se/), mainly on the eastern coast and approximately on the same latitude as the Finnish records have been made.
Tretomyces microsporus was found at Inari, 350 km north of previous records. The known occurrences of the species are concentrated in eastern Finland, with many findings from pine dominated, dry heath forests. It is possible that the species also occurs widely in northern Finland and elsewhere, since suitable habitats exist. Hyphoderma obtusiforme was also found at Inari, 400 km north of its previous known locations. We propose that the species occurs throughout Finland and in the area between this large gap. Candelabrochaete septocystidia and Amaurodon mustialaënsis were both found 300 km north of their earlier known occurrences. Both species are rare and probably have a southern distribution.
The new record of Sistotrema luteoviride from Sotkamo (3b) is ca. 600 km south of the previous records in Utsjoki (4d) [29]. Globally, S. luteoviride is extremely rare and these are the only three records in the world. The record in Sotkamo was derived from a thin Populus tremula trunk, whereas the substrata in Utsjoki -within approximately 2 km of each other -were thin corticated Juniperus communis. The habitats were also different; Sotkamo is an old, spruce-dominated, herb-rich heath forest with a large amount of young deciduous wood (mostly Populus tremula and Salix caprea, but also Alnus incana, Betula sp., and Sorbus aucuparia), whereas Utsjoki is a pine-dominated, dry heath forest and mixed river-side forest with birch, willow, and juniper. S. luteoviride is a mycorrhizal fungus for whom the substrate for the basidiocarp is not important, but the host tree is. Kotiranta and Larsson [29] reported two sequences from the root tips of Salix reticulata from an alpine ecosystem in northern Sweden and one from a cloud forest from Quercus laurina in Mexico. Why S. luteoviride makes so few basidiocarps remains a mystery.

Conclusions
A wealth of knowledge on the occurrence and distribution of aphyllophoroid species has been accumulated during the last ten years. A total of 65 nationally new species, 329 records of rare species, and 481 regionally new species have been reported from Finland after publishing the first Finnish checklist of aphyllophoroid fungi [2]. Nevertheless, the occurrence and distribution of aphyllophoroid fungi in Finland are still inadequately described and, in many cases, poorly understood, as demonstrated in this paper. It is obvious that tens of species can still be discovered if further field surveys are performed, particularly concentrating on remote areas, neglected and little studied habitats and substrata, species with minuscule basidiomes, and taxonomically challenging groups. For many species, the few existing records are from distant geographic locations, yet it is doubtful that their distributions are so scattered in reality, with many of these species likely occurring at several sites between the scattered observations. To elucidate the prevalence, distributional areas, habitat requirements for conservation purposes and red-list assessment for these species, more effort should be applied to species inventories and studies of fungal ecology.