FAQ: Temporary Code Names for Macrofungi
How Temporary Code Names Help Us Map Fungal Biodiversity
Also view our primary post on Temporary Code Names for additional detail, context, and practical usage information.
If you've encountered mushroom names like Amanita “sp-IN01” or Hygrocybe sp. 'conica-MI03' and wondered what those codes mean, this article should be able to provide you some clarity. Names in this form are Cryptonomen temporarium (“temporary hidden names”) - commonly called “temp codes.” They are a practical system used by many North American mycologists to organize and study fungal biodiversity when traditional species names are uncertain or unavailable. Think of them as placeholder labels that help scientists connect specimens, observations, and data while the slow work of formal taxonomy catches up. Whether you're a curious mushroomer who spotted these codes on iNaturalist, a student learning about fungal diversity, or a researcher working with biodiversity data, this guide explains what temporary codes are, why they exist, and when (or if) you need to care about them. Most importantly, it clarifies how these codes are research tools—not something most mushroom enthusiasts need to memorize or use in the field.
What are temporary code names, and why do we use them?
Temporary code names are interim identifiers applied to fungal collections that have been DNA barcoded, when the taxonomy is unclear or unsettled. They provide a way to organize and connect biodiversity data while avoiding premature or inaccurate assignment of formal species names. The goal is to create a working outline of biodiversity that can later be refined into permanent classifications.
What is the broader goal of this system?
Our current aim is to produce a reasonably comprehensive outline of North American macrofungal biodiversity within the next decade. An “outline” is essentially a first-pass triage: gathering baseline data (images, specimens, metadata) for each taxon and giving them an initial sort.
Each new collection sharpens the picture, improving the clarity of species boundaries and the quality of the sort. Once this foundation is in place, we can move beyond just documenting “what exists” and begin tackling deeper questions about ecology, function, and evolutionary history.
How are temporary code names different from species names?
A formal species name is intended to be stable, permanent, and governed by the botanical code. Temporary codes, by contrast, are not permanent, not formal, and not intended to replace formal nomenclature/taxonomy. They exist only to bridge the gap between data collection and final classification.
Why are these names being used? Why not just use species names?
Some precepts and needs to consider:
1.) Most macrofungal species are undescribed, so applying existing names to most collections is impossible.
2.) For described species, the original type specimens rarely have DNA sequences, making confident application of current names unrealistic. Even if sequencing of types were prioritized, many are centuries old, degraded, and dispersed across hundreds of herbaria—making large-scale sequencing infeasible in the near term.
3.) Many (most?) past descriptions are in need of significant revision, as they represent conflations of multiple species into a single description, or lacked adequate sampling to fully diagnose the range of morphological/ecological/geographic variation that actually exists for the species.
4.) Even when proposed by experts, very few identifications in GenBank are reliable, often for the reasons in (3) above.
5.) We need a fast, efficient, and public method to be able to link putative species-level units between datasets.
6.) Sequences need to be annotated as novel or linked to other matching sequences in real-time as they are discovered.
7.) The system should be flexible enough to incorporate polyphasic identifications and be independent of a single species concept (morphological, phylogenetic, etc).
8.) Previous systems that use aff. or cf. are insufficient, as they don’t allow putative species to be consistently linked and tracked.
9.) At the current rate of mycological progress, it will take hundreds or thousands of years before most species have names and we could assess biodiversity based on described species. Environmental impact assessments, conservation planning, and ecological models cannot wait centuries for formal names.
10.) Many past species descriptions are actually synonyms of earlier names and will ultimately be deprecated. Although ~150,000 fungal species have been described, the true number of valid, distinct species will be far lower.
These names are meant to provide a framework that allows systematic progress to document biodiversity to continue despite these issues, until formal taxonomy catches up.
Do temporary code names mean something is a new species?
No. A temporary code name does not imply novelty. It simply means that more work is needed to clarify what the taxon represents. Sometimes it may indeed turn out to be a new species, but in other cases the taxon could correspond to an existing species, a subspecies, a variety, or even an already-known species with confusing historical descriptions.
Are temporary code names the same as OTUs?
Not exactly. Some assume code names are just sequence-based clusters (mOTUs - molecular operational taxonomic units). In reality, they are usually polyphasic delimitations: meaning they take into account not only DNA sequences, but also morphology, ecology, geography, and seasonality whenever possible.
Further, must published research looking to form mOTUs utilizes published barcode data from public repositories without first correcting it for non-phylogenetically informative regions, ambiguous nucleotides, common sequencing errors, etc. This will typically give suboptimal measures of intraspecific and interspecific variation, and thus suboptimal results. We make corrections for all of these common sequencing errors and artifacts as a standard part of the analytical pipeline when assessing new barcodes and making new polyphasic delimitations.
Why do you call them “temporary” instead of “provisional”?
“Provisional” suggests a formal, diagnostic step toward naming a species. “Temporary” emphasizes that these codes are short-term, limited-use placeholders. They are not meant to be stable or definitive, only functional until better evidence is available. A provisional name may take the form of Amanita “banningiana” or Amanita banningiana sp. prov. - a format more similar to a final latinized species epithet.
Are temporary code names stable?
No. They are iterative by design. As more data becomes available, codes may be split, merged, or abandoned. Their job is to connect datasets and flag uncertainty, not to provide lasting labels.
Should I bother learning temporary code names?
Usually, no. Their main purpose is to organize datasets and connect records across projects, not to provide field names for mushrooms. For example, knowing that Pluteus romellii in North America consists of multiple lineages (formerly romellii-IN01, IN02, IN03, IN04) is useful in a research database, but not in everyday mushrooming. In most cases, it’s easier to use a group name (e.g., Pluteus romellii group) in conversation.
How should I talk about these fungi with a general audience or students?
Generally, don’t use code names unless there is a specific reason to. They aren’t meaningful or searchable to the public without special training. Instead, use familiar examples and accessible explanations:
Example: “We know the classic Christmas mushroom, Amanita muscaria, is usually red. But in our region, the common form is orange, and we now know there’s also a less common sister species that is light yellow. Science hasn’t named yet.”
This approach conveys the uncertainty without bogging people down with codes.
Why do some code names seem more precise than others?
Not all codes are created equal. Some represent well-documented taxa supported by many collections and could be described formally at any time. Others rest on a single collection with minimal information. The level of confidence and precision varies widely.
Who should use temporary code names?
They are mainly useful for researchers, data curators, and taxonomists who need to:
Link specimens across databases.
Track lineages while awaiting formal description.
Flag areas of taxonomic uncertainty for future work.
When is it appropriate to move from a code to a formal description?
A taxon is ready for description when there are enough collections to characterize its morphology, range, and ecology, and there is reason to believe it is distinct. A good starting point is 5–10 well-distributed collections. Descriptions based on only two or three specimens can work but are less robust.
Is DNA sequencing required for a new species description?
Strictly speaking, no. A detailed morphological description with multiple specimens is sufficient. However in a modern context, a DNA barcode (ITS for fungi) is typically expected and highly valuable. Multi-locus data or genomes are optional but can add weight.
What if type specimens cannot be sequenced or is lost?
In that case, the temporary code name for that species may last a while, until someone designates a modern epitype or neotype, notes the older ambiguous specimen, and moves forward.
Why doesn’t your lab describe new species right now?
Because the foundation isn’t solid enough for us yet. Many type specimens remain unsequenced, meaning new descriptions risk being overturned as soon as more historical data is incorporated. Our lab focuses instead on:
DNA barcoding modern collections of all North American species of macrofungi.
Outlining macrofungal biodiversity utilizing these temporary codes.
Working on optimal methods and workflows to extract data from old museum specimens.
DNA barcoding type specimens systematically, at scale.
Building scalable infrastructure for future taxonomic work.
We believe large-scale progress can only come once this foundation is in place. We are not interested in methods capable of describing 1, 10, or a hundred new species, but rather thousands. We will wait to focus on species descriptions until we can implement a program or method that is able to meet the scale of the problem in front of us.
How do I associate a temporary code name with a species once it is described?
Once a species is formally described, users will update databases and resources (e.g., MycoBLAST.org, MycoMap, iNaturalist, Mushroom Observer) to the new binomial. For practical purposes, the code should is then retired in favor of the formal name.
What happens if different groups create different codes for the same taxon?
This can happen. It’s a limitation of a system that’s meant to be temporary and decentralized. We regularly try to sync them as they are encountered. Ultimately, formal taxonomy and nomenclature resolve these overlaps. In the meantime, researchers can cross-reference codes when integrating datasets and make their own determinations.
Why not just wait until everything has a formal name?
Because formal taxonomy is slow and resource-limited. Commonly known, yet undescribed species may remain in limbo for decades or centuries into the future before someone takes the time to formally describe them. Temporary codes let us:
Capture and communicate what is known about the “species” in real time.
Connect observations across datasets.
Flag unresolved taxa for future work.
If we waited for only formal names, most biodiversity would remain invisible and unanalyzable.
Closing Note
Temporary code names are tools, not endpoints. They are most valuable for researchers building the scaffolding of biodiversity data. For the public and most mushroomers, it’s best to stick with familiar species groups until formal names catch up.
With sustained effort, we expect a reasonably comprehensive outline of North American macrofungi within the next decade. Every collection helps us move closer to that milestone.