Behaviour in cultures and habitat requirements of species within the genera Loreleia and Rickenella (Agaricales)

The term eco-geogram is introduced for surveying (in logical order) ecological and geographical data connected with fungal species. The database PILZOEK was established for that purpose. Eco-geograms are provided in this paper as an example for data retrieval from PILZOEK concerning the agarics Loreleia marchantiae, L. postii, Rickenella swartzii and R. fibula . The potential degree of endangerment is discussed in regard to habitat requirements. European species of Loreleia are not regarded to be endangered in Central Europe, although the risk to get threatened, because of low frequency of fruit body occurrence and quite a narrow substrate specialization, could be higher than in case of Rickenella fibula and R. swartzii. Cultures of Rickenella fibula, R. swartzii, Loreleia marchantiae (= Gerronema daamsii) and L. postii were investigated in regard to pigment accumulation, chlamydospore formation and some other characters.


INTRODUCTION
The genera Loreleia and Rickenella emerged taxonomically from the genus Gerronema in its broader sense, as it was originally interpreted by S i n g e r 1986. Various contributions to the generic concept brought evidence to the assumption that Gerronema in the sense of S i n g e r (1986) represents an artificial assemblage of species. Gerronema s. l. includes species with quite different requirements in regard to habitats and substrata. Some species are bryicolous (being transferred to Loreleia and Rickenella), some are lignicolous (being transferred to Chrysobostrychodes), some are lichenized (being transferred to Lichenomphalia), some are humicolous and finally some imply unknown or badly known habitat relations. For understanding the evolution and for being aware of the existence and of the endangerment of fungi, as well, it seems to be necessary to investigate substrate and habitat requirements in correlation to the phylogenetic position of the species in focus. In this contribution habitat requirements of selected fungal species will be arranged following a scheme ACTA MYCOLOGICA Vol. 41 (2): 189-208 2006 Dedicated to Professor Alina Skirgiełło on the occasion of her ninety-fifth birthday which has been designed for an ecological and geographical database for fungi (PILZOEK). A quite interesting question is, to what degree the endangerment of species is correlated with specialized habitat requirements. The chance for survival of a species depends largely on the availability of suitable habitats and substrates for growth and fructification. If such environmental prerequisites are restricted in any sense and if they are at the same time quite specialized, the risk of extinction might be much higher than in case of ambiguous ecological demands. That means that the endangerment of fungal species is largely to be understood in respect to their habitat relationships. In case of the macromycetes this fact is most important, since their predominating mycelial condition in the field is more or less invisible to the observer's eyes. The risk of endangerment is much higher in stenoecious species, which are restricted on very special and maybe vulnerable habitats, than it is in euryoecious species, which are able to survive under a variety of different environmental conditions, at least if some of them turn out to be well distributed, stable and not decreasing (B r e s i n s k y et al. 2005). The possible correlations between the existing or not existing degree of endangerment on one side, and habitat specialization on the other side, will be discussed in this paper along the example of four bryicolous Gerronema s.l. -species assigned nowadays to the genera Loreleia and Rickenella, respectively.

METHODS
The culture experiments with species of Loreleia and Rickenella have been performed by Angelika A c h h a m m e r ( -S c h ö t z ) (1986) in the lab of the senior author.
-Gerronema strombodes (Berk. et Mont.) Singer , obtained from fresh material, Germany, Bavaria, Weiherholz, Ascholding, 18.08.1984, leg. A. Bresinsky et A. Einhellinger. - Medium for cellulose-test (Ta n s e y 1971): Moser-b-medium without maltose, however, with glucose (4g / 10g) and cellobiose (10 g / 4 g). Addition of 5.0 g swelled cellulose in form of a diluted suspension. Water was added as much as necessary to obtain a total volume of 1 liter; pH 6. No agar was added for preparation of a liquid medium.
Casein-Mb-medium: A) Moser-b-medium. Water was added as much as necessary to obtain a volume of 700 ml; pH 6. -B) 30 g powdered skim milk was diluted in 300 ml aqua dest. -A) and B) were autoclaved separately and then, at a temperature of 45 o C, united (A n d e r s o n 1962; We y l a n d 1970).
Gujacol-Mb-medium: 0.05 g Gujacol was added to Moser-b-medium (B o i d i n 1951; L y r 1958).
Test for cellulase activity. The medium for the cellulase test looks originally dull because of the nature of swelled cellulose; cellulase activity of inoculated fungus gets visible by a clarified zone around the inoculum. Cellulase activity was evaluated semi-quantitatively by measuring the diameter of the clarified zone.
Confrontation tests with Marchantia. Thalli of Marchantia, or parts of it (clones), were washed and sterilized with ethanol (96%) and then placed on a medium (see above "culture media") in Petri dishes. The rhizoids were exposed to the surface of the medium which had been inoculated with the fungus in advance. Later, inocula were also placed close to or on the thallus of the liverwort. Then the Petri dishes (containing the liverwort and the fungus) were kept in a humid chamber.
In a modified arrangement Marchantia was grown in flower pods and then directly inoculated with the fungus. The inoculated pods with Marchantia were kept in a humid chamber which was, once a day for one hour, ventilated.
Data base PILZOEK. The ecological data connected with the species treated here have been collected by means of the data base PILZOEK (B r e s i n s k y , D ü r i n g 2001). The input of data is at its preliminary stage. So far it includes, as a matter of fact, only a restricted number of the available data from Germany and its neighbouring countries. The database will be completed steadily by the senior author of this paper. Most valuable data came from publications on mycocoenological interrelationships which had been elaborated through mycologists in Poland, in the tradition of intensively and long lasting efforts in that country (going back to S k i r g i e ł ł o , At present about 11.000 sets of data are incorporated in the database PILZOEK. Each data set represents a linkage of fungal species with ecological / geographical factors (one fungus species with many factors or, respectively, one factor with many fungal species). The current over-all-number of connections established in the database is estimated to a rate of 160.000. The data, which are included and stored in the database, can be retrieved by different options. It is possible to start inquiries for ecological and geographical factors linked with a selected species in focus (i. e. pre-selection of one fungal species results in a list of ecological and geographical factors connected with that species). Another possibility is to ask for lists of fungal species connected with a selected ecological or geographical factor (i. e. pre-selection of an ecological or a geographical factor results in a list of fungal species connected with that factor). The database is accessible free of charge for everyone via internet (http://www.pilzoek.de; for details see B r e s i n s k y , D ü r i n g and A h l m e r 2005).
The final design of the database PILZOEK and its presentation in the internet was made possible through a grant of the German Ministry of Education and Research in the context of the BIOLOG-program (BIOLOG = biodiversity and global change).

RESULTS
The available ecological data in regard to the species Loreleia marchantiae, Loreleia posti, Rickenella swartzii and Rickenella setipes are listed and discussed. Geographical data will be mentioned on the European and world-wide scale only; regional distributional patterns are neglected in this paper. The survey of speciesbound ecological characters according to a scheme of order will be named ecogram (in analogy to the terms program, telegram, etc.) and for the survey of geographical (distributional) traits the term geogram is introduced here; for both together, the term eco-geogram is applied. The listed code numbers are identical with those which are implemented in the data base PILZOEK. The hierarchy of code numbers reflect a given scheme of order for the presentation of data (survey in B r e s i n s k y , K r e is e l and Pr i m a s 1995) which makes additions of new records or a search for special information easier. References on mentioned factors (f. e. in the discussion) may be given in short form by code numbers only. The data will be presented in different sections (A-I) which are part of the data presentation program of the data base PILZOEK; in the context of the species treated here, some of the sections will be found omitted (f. e. E, H). The sources of the data presented in the eco-geograms are indicated by the names of authors and contributors. The full citations of sources (of incorporated data) are given in the database PILZOEK and are accessible through the above mentioned internet address; therefore, these will be omitted here.
Abbreviations used for countries / regions: Cultures of both species exhibit quite a high cellulase activity which can be interpreted as necessary in order to penetrate the cells of the bryophytes and to live as parasites. If mycelia of L. marchantiae are confronted with thalli of Marchantia polymorpha, the hyphae of the fungus penetrate into the host and are found then predominantly within the tuberculate rhizoids (Fig. 1B); later partly also within the tissue of the thallus (Fig. 1C). The hyphae of L. marchantiae develop on (= on rh), or, respectively, within the rhizoids (= in rh) of Marchantia different structures: appressoria (on rh), penetration hyphae (in rh), vesicular haustoria (in rh), chlamy- dospores (in rh) and oidia (in rh). Since no damage or restricted growth of the infected thallus can normally be observed under natural conditions, some kind of symbiotic interrelationship between both organisms might exist, in analogy to (endo-) mycorrhizal interactions in higher plants.
In fresh material which had been collected in the Botanical Garden in Cracow, Poland, G u m i ń s k a and M i e r z e ń s k a (1992) observed an association of L. marchantiae not only with smooth and tuberculate rhizoids of Marchantia but also with coenobia of cyanobacteria belonging to the genera Anabaena and Nostoc. These cyanobacteria were not found in uninfected thalli of Marchantia. In thalli infected by the fungus they were observed in the lower parts of the thallus chambers, between the rhizoids and at the base of the stipe. The authors conclude that the fungus mediates between cyanobacteria and liverwort through hyphal connections making accessible nitrogen compounds produced by the former. Parasitism has to be excluded in the view of these authors.
Another interpretation is possible in the sense that L. marchantiae behaves as a weak parasite or as a saprobiont and, indeed, a record made by the senior author exhibited a necrotic area of Marchantia polymorpha around the attachment of the stipe of the fungus (notes on the record in S c hmid-Heckel 1985).  [PL]. C. Habitats: 11.1 humid woods with maple (Aceri-Fagenion). 14.14 ash-alder-and alder-ash-wods along brooks. Comments. Fruit bodies of Loreleia marchantiae are observed only seldom. Nevertheless the species might be distributed quite well and shall be expected at any place where thallose liverworts are forming expanded mats. The specialization on few genera of liverworts for fructification and the presumed interrelationship with Cyanobacteria (G u m i ń s k a , M i e r z e ń s k a 1992) could be the reason for a potential endangerment of the fungus. On the other side, the occurrence of Marchantia is favoured by human activities (greenhouse culturing, fire places, nitrification, application of herbicides) and it might be quite likely that L. marchantiae is able to follow its host everywhere. The fungus is "growing in disturbed habitats, e. g. soil treated with herbicides (L i s i e w s k a , B a l c e r k i e w i c z 1991), on mud along ditches, between bricks along roads etc." (B a s et al. 1995). It has to be considered, that the fungus might be much more frequent and distributed in its mycelial stage than it is indicated by its rare fructification, thus being mostly not apparent to the observer. Generally, rhizoids and thalli of liverworts have been found to be quite regular infected by fungal hyphae (N i c o l a s 1967). In case of L. marchantiae a higher humidity is apparently afforded to enable fructification of the hosted fungus. Thus, fructification in countries and areas with humid climatic conditions is more likely to be expected (oceanic climatic regime) than under more dry conditions of a continental climate. Maybe, that this is the reason why this species has been recorded as being not so rare in Western Europe (B a s et al. 1995) and why it is so far missing or rare in the Eastern European countries. Observations. The species in its broader sense has been reported to be bound to thallose liverworts (f. e. Marchantia), peat mosses (Sphagnum) and mosses (Ceratodon, Funaria, Polytrichum), as well. The distinction of Loreleia postii s. str. from L. marchantiae, in the sense of C l é m e n ç o n 1982, on behalf of the association with thallose liverworts on one side (in case of L. marchantiae) and with mosses on the other side (in case of L. postii s. str.) seems to be quite hypothetical at the moment. The discriminating morphological characters between both species are minute and intergrading (D e r b s c h 1977); moreover, it is not clear if any kind of correlation does exist between the choice of hosts (liverworts versus mosses) and genetic or morphological characters. In recent studies (K l á n 1992; B a s et al. 1995) the separation of both species is not based on different hosts rather than exclusively on morphological characters: the pileus in L. marchantiae is claimed to be not striate, in L. postii it is striate. Other differing features are mentioned for the margin (crenulated in L. marchantiae; entire in L. postii), for the gills (distant and forked in L. marchantiae; close and not forked in L. postii) and for the spores with slightly differing, however, overlapping sizes. All these differences could simply reflect different developmental stages of one and the same species.

Eco-geogramm for
The pigmentation and morphological appearance of cultures (L. marchantiae and L. postii) were very similar to each other. Confrontation of dicaryotic mycelia of both species did not result in any kind of barrage neither in a marked confrontation zone. Instead of such expected behaviour, the mycelia of both species intermingled with each other. In the area of first interspecific hyphal contacts quite a number of anastomoses between intermingling hyphae could be observed, much more than near inocula of both species. However, it could actually not be decided if the anastomoses were inter-specific or intra-specific. From these observations it might be suggested that L. marchantiae and L. postii are very close to each other, if not even conspecific.
Evaluating the experimental observations, one should be aware of the fact, that the results are as good, or as bad, as the strains being used were correctly identified ore not. It is possible that the strains which were cultivated as "postii" and "marchantiae" represented only one species, eventually only L. postii. Such an identity would explain the observation that the mycelial culture of G. daamsii (= L. marchantiae) behaved quite different from those labeled as "postii" and "marchantiae". Another possibility explaining the different behaviour of G. daamsii (as compared to L. marchantiae and L. postii) could be a contamination of its culture with another fungal species. In this case, however, it is surprising enough that in confrontation tests the hyphae of G. daamsii were found to penetrate into the rhizoids of Marchantia as one would expect it for true G. daamsii and L. marchantiae.
At Comments. The data concerning distribution of the species belonging to Loreleia in Europe are probably not always correct since separation between L. postii s. str. and L. marchantiae (including G. daamsii) is still quite obscure, depending on different interpretations of taxa. L. postii s. str. seems to be rather rare, however, eventually not endangered, since it is reported to occur also in man made habitats like burnt places (31.8) and on flower pods (30.91). However, it is not absolutely clear if all of these indications apply only on L. postii, and not partially also on L. marchantiae. Low frequency of distribution and specialization on few habitats may cause indeed a higher risk of endangerment. If L. postii should exclusively be restricted to mosses as substrate, then the grade of endangerment might appear to be higher. On the other hand, some of the mentioned host species among the mosses are widely distributed and common: Funaria hygrometrica is growing everywhere on fire places (31.8) and Ceratodon purpureus is by no means rare.

Rickenella swartzii (Fr.) Kuyper
Syn.: R. setipes (Fr.) Raithelh., Gerronema setipes (Fr.) Singer Observations. Spores of this species and of Rickenella fibula, respectively, germinated on suitable media, but not reliable and not always to a high percentage (as it has been already stated by L a m o u r e 1979). The cultures of Rickenella swartzii and R. fibula showed identical or very similar characters. The readiness of spores to germinate depended on the season. If spores were collected in early summer (July) or in late fall (October), then the readiness to germinate and the speed of growth of arising hyphae was much higher than in the case that spores had been obtained in the time between these months. The regular pigmentation of cultures was whitish, ochraceous, or brownish, varying in intensity and colour from strain to strain. In some cultures pigments similar to those of the fruit-bodies accumulated if the cultures were grown in the spring and kept in day light.
Cultures of R. swartzii (03-06-84) on Casein-Mb-medium exhibited violet pigments, and on Gujacol-Mb-medium violet and orange pigments. In other words, both components of pigmentation were evident which are typical for the carpophores. A transfer of the cultivated mycelia from liquid culture medium to a solid culture medium (in this case prepared by adding an extract of Hypnum cupressiforme to the standard ingredients) increased the intensity of pigmentation sometimes.
Eco-geogramm for Rickenella swartzii (using database PILZOEK): Sources: Achhammer 1986; Antonin, Noordeloos 2004;Arnolds 1977Arnolds , 1981Babos 1989;Bas et al. 1995, Besl et al. 1982Bresinsky 2000;Bujakiewicz 1973Bujakiewicz , 1979Bujakiewicz , 1982Bujakiewicz , 1986Courtecuisse 1994;Derbsch, Schmitt 1987;Einhellinger 1964Einhellinger , 1976Einhellinger , 1977Einhellinger , 1982Gulden, Torkelsen 1996;Gumińska 1976;Hallgrimsson 1981;Hansen, Knudsen 1992;Haeupler et al. 1981;Horak 1963;Jahn et al. 1967;Kalamees, Vaasma 1981;Kost 1984;Kreisel 1957Kreisel , 1970Kreisel , 1987Krieglsteiner 1991Krieglsteiner , 2000Krieglsteiner L. 1999Krieglsteiner L. , 2001Kühner, Lamoure 1986;Lambinon et al. 1977;Legon, Henrici 2005;Luschka 1993;Malençon, Bertault 1975;Miller, Farr 1975;Neuhoff 1949;Nuß 1999;Paulus 1981;Ricek 1989;Schmid-Heckel 1985;Sedlmeir 1985;Skirgiełło 1998;Šmarda 1973;Sonneborn, Stangl, Sedlmeir and Geh 1987;Urbonas, Kalamees and Lukin 1986;Watling, Rotheroe 1989;Winterhoff 1993Winterhoff , 1993bWinterhoff , 1994Winterhoff , 2001bWinterhoff , 2002Wojewoda 2003;Wöldecke Kn. 1990  Comments. In case of Rickenella swartzii the frequency of distribution in terms of observed carpophores in the field is much lower than in R. fibula. Nevertheless, the species is most likely not threatened, because it grows and fruits in numerous and various habitats which are to a greater extent (so far) not endangered. The occurrence in man made habitats which sometimes are rich in nutrients demonstrates that the species has quite a high capability to survive the decrease of vulnerable, nutrient poor habitats. The readiness of spores to germinate and to establish mycelia under not absolutely fixed biotic and abiotic conditions is also in favour for quite a high probability to survive and to fruit in sufficient frequency. These conditions altogether contributed apparently to the evaluation of a not threatened species; it is f. e. not included in Red Data Lists of Poland (Wo j e w o d a , Ł a w r y n o w i c z 1992) or of Germany (B e n k e r t et al. 1996). In regard to host selection its interrelationship to genera and species of bryophytes (see 5.71 / 5.72) appears not very much specialized. The occurrence on few genera of bryophytes only would result in a higher risk for its existence. According to our present knowledge R. swartzii does not occur on Sphagnum and not on foliose or thallose liverworts. The host selection is somewhat narrower than in case of R. fibula, however, much broader than in case of Loreleia-species. Observations. Mycelial cultures produce in accordance with the colour of the fruit bodies an orange pigment, at least under lucky circumstances. In all other cultural characters R. fibula is similar to R. swartzii.
In addition to the observations of L a m o u r e (1979) on dispersed growing colonies some microscopic features could be observed which are characteristically for colonies of Rickenella growing in more or less dense clusters. In such a situation the dicaryotic hyphae are composed of rather short cells and clamps are often missing at the septa ( Fig. 2A). Hyphal branches show often chains of chlamydospores. These germinate sometimes in situ with clamped hyphae (Fig. 2E). It seems that chlamydospore formation is induced by the existence of many zones of inhibition created by dense growth of numerous colonies on restricted space. In contrast to this crowded situation, typical chlamydospores are not developed from isolated growing mycelia. Many weeks later, Peziza-like structures occasionally appeared between the densely growing dicaryotic colonies. These Peziza-like structures are in terms of their hyphae similar to dicaryotic hyphae, however, clamp-less and with uninucleate instead of binucleate cells (Fig 2F). In freshly isolated cultures the mycelial growth exceeded with diameters of colonies up to 25 mm (in our experiments) that of older strains with diameters between 4 and 16 mm after 6 weeks (L a m o u r e 1979).
The cellulase activity appeared in Rickenella to be lower than in L. marchantiae and L. postii [and of course lower than in the wood inhabiting species Gerronema (Chrysobostrychodes) chrysophyllum and G. strombodes]. This observation is in agreement with the assumption that Rickenella-species do not cause any damage to their bryophyte hosts by virulent attack of the cell walls of living cells. Rickenella-species are not strong parasites rather than either saprobionts (living from the death parts of their hosts which in this case are not severely influenced by the hosted fungus) or even symbionts (establishing some kind of endomycorrhizal interrelationship as assumed by K o s t 1984). The latter assumption is supported by field observations: Rickenella fruited year by year on the same bryophyte thallus without setting a remarkable harm to its host. Fruiting began according to our observations on Hylocomium splendens in the mid of August when fresh green branches arised from the cauloids of the preceding year; then the fruit bodies of Rickenella fibula were fixed just underneath the fresh green sections on those parts of the cauloids which were bearing dead leaflets only.
Besides many species and genera of mosses also the liverwort Marchantia polymorpha has been listed once to be associated with Rickenella fibula ("among specimens of Marchantia polymorpha"; D y l ą g , G u m i ń s k a 1997). It is uncertain if in this case Marchantia really served as substrate. Especially if the fungus is found on burnt places (31.8) in association with Marchantia, it is not unlikely that Rickenella fibula might be mistaken for Loreleia marchantiae. Attention should also be paid to R. pseudogrisella (A.H. Smith) Gulden. This species is bound to the liverwort Blasia pusilla and was found in arctic-montane habitats of Scandinavia (N, S, SF), of Island and of Greenland (H a n s e n , K n u d s e n 1992; L u d w i g 2001); it has not been recorded so far from Poland neither from Germany where it could, however, be expected in the alpine zone. Records resembling R. fibula, but exhibiting more dull ochraceous instead of vivid orange colours of fruit bodies, should be identified as R. mellea (Singer et Clémençon) Lamoure. This taxon has been observed among mosses of the genera Bryum and Philonotis; it has been found recently in Germany (L u d w i g 2001) and may occur in Poland too. Attempts to distinguish other taxa on the species level bound to special host species of bryophytes (f. e. Rickenella aulacomniophila Kost on Aulacomnium palustre) failed. The discriminating characters like different size and shape of cystidia turned out to be extremely variable within a rather broad range of continuous variation; this might also apply on differences in spore sizes in R. mellea as compared to R. fibula.
In Bavaria the highest frequency of fruit bodies of Rickenella fibula had been observed by us 1985 on Hypnum cupressiforme, Dicranella heteromalla, Rhytidiadelphus squarrosus, Brachythecium rutabulum, Plagiomnium affine, Hylocomium splendens and Pleurozium schreberi. On a single patch of moss, measuring approx. 10 cm in diameter, 10 or even more fruit bodies have been counted in case of Hypnum cupressiforme, Dicranella heteromalla or Plagiomnium affine. In different months of the season different species of bryophytes were preferably carrying fruit bodies. In the area of Regensburg, Bavaria (125 records evaluated), Hylocomium splendens was observed to bear fruit bodies mainly in August, Plagiomnium affine and Pleurozium schreberi mainly in September and Dicranella heteromalla mainly in October at the end of the mushroom season (then being the most important host to carry carpophores of the fungus). The fungus can be attached to different parts of the host: main axis and lateral branches of cauloids, rhizoids and leaflets. In

DISCUSSION
The species of the genera Loreleia and Rickenella are not regarded to be endangered in general. This applies to some extent even on species which are quite rare or only occasionally observed.
Rickenella swartzii with a low grade of frequency as compared to R. fibula is nevertheless not threatened. Its low frequency of records may be caused by a lower rate of readiness for fruiting. This does not necessarily mean endangerment since a high potential is inherent in Rickenella (and Loreleia) to disperse by asexual germ cells (oidia, chlamydospores). The habitat requirements are broad enough to include sites with higher contents of nutrients in the soil (28.11.01, 28.13, 30.7, 30.91), and the association to bryophytes as substrates is wide enough to permit the fungus to be present on bryophytes which are not sensitive against man made environmental changes and restrictions (5.71 / 5.72: f. e. Hypnum cupressiforme, Rhytidiadelphus squarrosus).
The estimated rarity of the Loreleia species may be the result of inadequate observation. In case of L. marchantiae the host plants, mats of thallose liverworts, are not checked intensively and regular enough by mycologists over a greater period throughout the whole year. Thus the fructification of L. marchantiae, if it occurs for a short time, may be overlooked quite often. One has to consider that the fungus might be well distributed in its mycelial stage. It is, however, seemingly rare since observations are based on fruit bodies only. It is hard to believe that a fungus which is easily growing in cultures and which is provided by different, readily germinating propagules should not be fit enough to find spontaneously its hosts in order to develop mycelia and asexual diaspores. The low range of hosts and the specialization on genera with only few species (as in Marchantia and in Lunularia) does apparently not afford a higher rate of genetic variation which would be warranted by sexual reproduction in fruiting bodies. Once being adapted to its few (in terms of evolution more or less stabilized) hosts, such fungal species may be not dependent on sexual reproduction in fruit bodies for their survival. This might be one reason for rare fructification. Again the rating of being not endangered is based on the evaluation of habitats and substrates. These (i. e. the substrates for Loreleia marchantiae) are not recorded to decrease or being threatened; in other words, the species within Marchantia and Lunularia, serving as substrates, are not listed as being endangered. Lunularia cruciata is quite often found in man made habitats like parks, green houses, flower pods etc. It shows an increasing tendency to expand and to invade also natural habitats in Central Europe. It is, however, susceptible to freezing temperatures and may die back in a cold winter; its distribution is much more oceanic than continental. Within Marchantia polymorpha it is ssp. ruderalis which is the most distributed infraspecific taxon, whereas ssp. polymorpha is more restricted in its distribution. It is not likely that Loreleia marchantiae does prefer one of the both subspecies as a host.
Wide availability of suitable substrates is warranted also in this case of substrate interrelationship, because of a sufficient wide range of appropriate habitats and because of the synanthropic and nitrotolerant character of the host species (especially Marchantia polymorpha ssp. ruderalis). The evaluation of endangerment in case of L. marchantiae gets a new dimension in the light of a possible interrelationship with two partners. The dependence from Cyanobacteria in connection with liverworts complicates the existence of the fungus in a sense that the chain of nutrition is not easily established and if so, then it is more vulnerable. Such complex interdependence causes a higher degree of possible endangerment.
Finally it has to be taken into account that unclear taxonomic concepts on the species level complicate the evaluation of the endangerment of species. A narrow species concept within Rickenella (fibula) would distinguish separate micro-species on special bryophytes serving as substrates (f. e. R. aulacomniophila on Aulacomnium). Some of the taxa to be distinguished in a narrower sense could fulfil the criteria of being threatened because of their more restricted range of substrates and habitat conditions. The transfer of R. aulacomniophila into the synonymy of R. fibula, as it has been advocated in this paper, includes the risk of getting sightless against the situation of actually threatened organisms. In the context of Loreleia marchantiae the risk of endangerment would be lower if this species would fall into synonymy with L. postii. In this case the range of substrates, including mosses and thallose liverworts as well, and the habitat requirements would be quite wider than it is supposed in the view of a narrow species concept.