Lichenicolous Fungi of the Pacific Northwest

The Lichenicolous Fungi of the Pacific Northwest:

A Multi-level, Searchable Compilation of Fungi Records and Their Lichen Hosts

Mike Haldeman and Sunia Yang

This website is a searchable compilation of all the lichenicolous fungus records with their lichen hosts from the Pacific Northwest of North America. The compilation includes all records that we have found in the scientific literature. It also includes records that we have found in our own searches and in searches of the herbarium at Oregon State University as well as records of Bruce McCune and Daphne Stone. We have made no attempt to solicit records from other lichenologists at this point. Nor have we attempted to extract information from MycoPortal or CNALH, because the editing and verification time that may be required is beyond our current capacity.

The format allows for a search through all the host lichen-lichenicolous fungus interactions based on the genus or species of the host lichen or on the genus or species of the lichenicolous fungus. If aggregation is set to “None” all records will be displayed, first in alphabetical order of the host, then alphabetically by the lichenicolous fungus. Alternatively, the displayed results can be aggregated by the lichen hosts or by the lichenicolous fungi or by host/fungus pairings. If one of these aggregations is chosen, the results will be displayed followed by the number of records for that item and without other details. All the results will be preceded by “+” symbols. These allow for expanding the display to show the desired records. There is also an option for full record details (complete) or an abbreviated display with fewer details (brief). The brief version will give the pairing along with state/province, county and reference. The complete version adds more specific location and habitat details. Finally, there is a dropdown for state/province. This may be useful to narrow the focus when dealing with common fungi, for which there are many records. It may also be useful to quickly check if a species has been recorded for a state or province yet (of course, we may have missed some and are continually adding records.)

As of February 2021, this site contains over 1600 records of host/lichenicolous fungus pairings involving 426 lichenicolous taxa. As we scoured the literature, we included all records we found from the Pacific Northwest. As a rule, all records from British Columbia, Alberta, Washington, Oregon, Idaho, Montana and Wyoming were included. Northern California was also included with all records from Monterey and Tulare Counties and northward added (but not necessarily Inyo and Mono Counties). Southeast Alaska was also included as well as records up to and including Kodiak Island and Denali National Park. There has been much work on lichenicolous fungi south of this region in southern California (Knudsen and Kocourková 2009, 2012; Kocourková et al. 2009, 2012; Tucker 2014 and many others) and to the north in more arctic regions of Alaska (Zhurbenko 2009a,b; Zhurbenko and Laursen 2003; Zhurbenko et al. 1995 and many others). But at this point, time is a limitation so reports from outside this main Pacific Northwestern area were mostly excluded. However, some records from outside this area were included. If a lichenicolous fungus was reported from relatively close by, on a host lichen that is common in the northwest, we may have included this. For this reason, one may see a few records from Colorado, Minnesota, Nebraska, Nevada, Saskatchewan, Utah, or elsewhere in California and Alaska.

If aggregation is set to “By Fungus Species”, following the species name will be a brief display of species attributes (79% complete as of February 2021). This is not meant to be a sole method of identification. Rather, this is a way to quickly rule out some of the possibilities. Without this attached group of attributes, one would be left with a list of scientific names that will not mean much to many users. But, with a list of a few attributes following each lichenicolous fungus name, users will be able to better focus their search. For instance, if one found a perithecioid fungus with 3-septate spores on a lichen, one could quickly rule out all the choices labeled “Basidiomycete”, “Apotheciate Ascomycete”, “Anamorphic Ascomycete” and “Calicioid Ascomycete”. (These broad categories are taken from Nash et al. 2004 which is a good place to start keying a lichenicolous fungus). One could also rule out other “Perithecioid Ascomycetes” that are labeled as having simple spores or many-septate or muriform spores, (but might still want to keep in mind those with 1- or 4- to 5- septate spores). Spore sizes are also included in the attribute list, but we would caution using this too strictly. These sizes are included to give a rough idea so that if one is dealing with spores 5-6 micrometers long a fungus with spores 25 micrometers long can quickly be ruled out. But by this point the user is likely to be down to only one or two choices. The end of the attribute list will show the reference from which these attributes were taken. In all cases, these references should be checked to verify an identification.

Because there is still much to learn about the lichenicolous fungi in the Pacific Northwest, this site is far from comprehensive. New species are frequently described and many well-known species in Europe, eastern North America and Asia are likely to reside in our area but have not been recorded here yet. For this reason, the process of elimination approach cannot be considered conclusive on this website. If you find a lichenicolous fungus and generate a list of lichenicolous fungi for that host lichen, this list should only be treated as a list of suggestions. It is intended to quickly point the user to a reference that can be used to identify their specimen. Under no circumstances should one just pick the closest match. There are just so many fungi out there that we have not recorded here yet or that have yet to be described. Unfortunately, one will often come to a dead end.

Host specificity is variable among these fungi. Some seem specific to a single species, while others show no host specificity. But most that we’ve researched seem to be specific to at least a host genus or family. However, be aware that the full host range for many of these species is regularly being updated. For this reason, the broader range of fungi given by a host-lichen genus search will often be more effective than searching by host-lichen species. In particular, the large, abundant genera Cladonia and Peltigera have many lichenicolous fungi and very few of these fungi have an affinity for a single species. But many appear to be restricted to one of these genera. So, when searching for matches to a fungus on Cladonia pyxidata for instance, using the genus search and choosing Cladonia will be more helpful than using the species search and choosing C. pyxidata. One might also consider checking other related genera. If one encounters a fungus on Solorina that does not match any of the records found on that genus it may be fruitful to check the related genus Peltigera, which will have many records, some of which may parasitize other Peltigeraceae. We also included a combined Lepra/Pertusaria category in the genus dropdown. These two genera share many lichenicolous fungi. Additionally, the most common member of the group in the Pacific Northwest, Lepra ophthalmiza, was until recently placed in the genus Pertusaria. It is likely that many records with hosts given as “Pertusaria sp.” refer to L. ophthalmiza.

Lists of certain lichen taxa will prompt a note at the top of the list. For instance, if one chooses to search by the lichen genus , a note will remind the user that this genus is related to Pertusaria and Lepra and they frequently harbor the same lichenicolous fungi. So, it may be useful to search Lepra/Pertusaria if a match is not found in the Ochrolechia results. Also, some lichen genera as currently defined are not monophyletic. The large crustose genus Lecanora is one such genus and some fungi seem to be more prevalent on groups within Lecanora. For these cases a note at the top of the list will remind users to search other members of that group or to search the group name itself, e.g. Lecanora subfusca group or L. varia group. It should be noted that searching by either of these groups will only display records where the group name was given as the host in the literature and not all the accumulated records for members of that group. However, the note will inform the user which members of the group have records in our database. For example, any search of Lecanora chlarotera, L. circumborealis, L. pulicaris or L. subfusca group will display the note “Also consider records from other members of the Lecanora subfusca group, so far represented here by L. chlarotera, L. circumborealis, L. pulicaris and L. subfusca group.” The subgenus Cladina is treated similarly. Other notes try to address ambiguity that may arise when old records give a host as genus only, such as Pseudocyphellaria sp., because this may refer to species that have since been moved to Lobaria.

Although most of these fungi seem to be restricted to a phylogenetic host group, others are indiscriminate. It is important to be aware of this. The common Lichenoconium erodens can be found on many different unrelated species, but so far in the Pacific Northwest we have records from only two different hosts. Other species of Lichenoconium are also generalists despite having misleading names like L. lecanorae and L. usneae. So, if you find a Lichenoconium on Nodobryoria abbreviata and use this site you will quickly find that L. christiansenii is a match. But it is still necessary to rule out the congeners mentioned above. Perhaps a future iteration of this site will have a separate file of generalist fungi of which to be aware. But for now, we want to draw attention to this one common but difficult to identify genus (Lichenoconium) and remind users that all identifications should be verified using a treatment of the group.

Of course, we realize that a more comprehensive and effective approach would have been to include all known records of lichenicolous fungi from throughout the world if they occur on a lichen species or even a lichen genus that is found in the northwest. For instance, if a new species is described on Hypogymnia physodes in Europe, that should be included here because it is very possible it occurs here too. The reason for not including these is simply time constraints. Our plan for now is to keep adding northwestern records as they are published and to add other relevant records as time allows.

Our hope is that this site will aid in many identifications by quickly giving some options for species identification and directing users to helpful literature. We also hope that this will entice more lichenologists and lichen enthusiasts to try to identify these organisms. This could give the scientific community a better idea of the distribution and true host specificity of these fungi since many of the fungi reported here are only known from one or two local (or world) records. In addition, we hope that this site will help to shed light on many species that DO NOT have a match on this list – species that occur here but that have not been recorded here yet, many of which are likely to be undescribed.

Nomenclature follows Diederich et al. (2018) for the lichenicolous fungi and Esslinger (2019) for lichens with some adjustments in unsettled genera to follow McCune (2017a, b).


The term “host lichen” is used even if the fungus is growing on another lichenicolous fungus. For example, when Abrothallus parmeliarum grows over Nesolechia oxyspora on Parmelia sulcata records for both fungi show a host of Parmelia sulcata. We did it this way because it is usually reported in the literature this way. But noting if an Abrothallus is on a lichen or on Nesolechia could be an important characteristic (Diederich 2011).

Calicioid fungi that have been reported as parasitic on lichens are also included in the main table. However, the individual species accounts do not usually have information attached. They state “Calicioid Ascomycete” and direct the user to several in-depth treatments of this group that deal with the parasitic, saprobic, and lichenized species together (McCune 2017a, b; Peterson and Rikkinen 1999; Rikkinen 2003; Selva 2014; Selva and Tibell 1999).

Lichenicolous lichens are included here, but these are lichenized fungi and so are treated thoroughly with lichen texts, especially Microlichens of the PNW (McCune 2017a, b). For this reason, the descriptions of these species are often incomplete or omitted. When common lichenicolous lichens (e.g. Carbonea vitellinaria and Epilichen scabrosus) have been mentioned in the literature without a host, which is common in regional checklists, those records have not been included. No host has been assumed in any of these records. Some common lichens begin their life cycle as parasites such as Diploschistes muscorum on Cladonia and Toninia spp. on various lichens (McCune 2017b). We have only included records of these species as lichenicolous fungi if they are specifically mentioned as lichenicolous or parasitic in the literature.

Often one will find small lichens growing on large lichens such as small thalli of Physcia starting on a large Peltigera thallus. These occurrences are not treated here since the lichen is only growing on the thallus and not within thallus tissues. This may also be said of Lichinodium spp., some records of which are included. The difference is that the Lichinodium records included here were specifically reported as lichenicolous, so we added them. Species may also be found growing into each other as is occasionally seen with Physcia and Xanthoria. These phenomena are not treated here.


Host pycnidia. If you find black spots on a lichen that prove to be pycnidia, do not assume you have a lichenicolous fungus. It is likely these are pycnidia formed by the lichen itself, so descriptions of the lichen pycnidia and conidia should be consulted. Unfortunately, these descriptions are not always easy to find. The genus and species accounts from the Lichen Flora of the Greater Sonoran Desert Region are a good place to look (Nash et al. 2002; 2004; 2007). These are available on the Consortium of North American Lichen Herbaria website ( and will be displayed on that species or genus page if that taxon was included in the Sonoran books. Also see McCune (2017b), McCune and Geiser (2009), Smith et al. (2009), and Thomson (1984, 1997) which describe pycnidia and conidia in many cases.

Bark and wood microfungi. If studying lichenicolous fungi on crustose lichens, especially on bark or wood, be aware that ascomycetous microfungi also grow on these substrates and may push ascomata up through crustose lichens. These ascomata are often dark and may blend in with bare bark but will be obvious growing through pale lichens such as some Biatora, Ochrolechia and Pertusaria. See Suija et al. (2020) for a description and photos of Pseudotryblidium neesii, a common fungus on Abies grandis bark, and Boehm et al. (2009) for descriptions and keys to many hysteriaceous species. Pseudographis elatina has also been reported from the region (Haldeman 2020, Karakehian et al. 2019) and may push through crustose lichens. Karakehian et al. (2019) provide information and photos of this and similar species. These are only a few of the possibilities in this under-explored group.


First, we would like to thank Bruce McCune for introducing us and bringing this idea to us. He was always available to discuss ideas and gave valuable input to make the site more useful. He also made his herbarium available and allowed access to the lichenicolous records from his database. Amy Rossman gave advice on which features might be most helpful and helped with some fungal identifications. Daphne Stone brought several interesting fungi from her work to our attention and was always available for advice. MH would also like to thank Paul Diederich for his help and advice with many of the identifications made for this project. Finally, we would like to thank Shirley Tucker for providing the herbarium improvement grant that allowed for the investigation of many of the OSC specimens and for the compilation of this data.