A request for Stereum specimens

Hello friends!

My name is Sarah DeLong-Duhon, and I am a master’s student at the University of Iowa. My thesis involves creating a global molecular phylogeny for the fungus Stereum, a genus that – before I began my investigation into the eastern North American species – had no molecular phylogeny despite being researched intensively for potential biomedical application. You can read my pre-print here: https://www.biorxiv.org/content/10.1101/2020.10.16.342840v2. To get well-documented specimens of these fungi worldwide, in addition to herbarium collections, I am soliciting specimens from citizen scientists!

How you can help

  • Make iNaturalist observations for Stereum or other genera of Stereaceae you encounter, and tag me @sarahduhon
    • Take lots of pictures, preferably of good resolution and not blurry
      • Top and bottom of mushroom, and the whole colony
      • Take enough pictures to help identify the host plant (Bark and leaf litter are helpful, and zoomed out photos that show environment where found)
      • Scratch the undersurface while fresh and take pictures to document any bleeding or color staining (some, when dry, will also stain color on wetting)
  • Send me specimens, especially from locations outside eastern North America
    • Are you in eastern NA? You are still welcome to send me specimens! I also highly encourage you to go out and make high-quality observations of Stereum using the instructions provided above.
    • Strong preference for these specimens to be associated with iNat observations.
    • Do it legally
      • Don’t trespass, don’t violate park/preserve rules, collect on private property with permission if laws prevent you from collecting in public spaces.
  • Spread the word to colleagues, especially anyone working in remote, undersampled locations. Where there’s wood, there is always Stereum.
  • Have any questions about what I’m doing, or advice? Leave a comment in the thread!
    • Professional or anecdotal advice on shipping specimens from other countries to the US is really appreciated - I haven’t nailed down the logistics yet.


“Eastern North America”

If you’re outside this circle, I want your Stereum! Especially if you are in one of these blank areas on the map.

Bleeding/Staining Color

S. gausapatum bleeds/stains red, and will do so when dry too if
you wet it (with water or saliva)

S. lobatum bleeds/stains bright yellow, and will also stain when
dry, as I’ve done here by wetting it

Zoomed out photos / context for host ID

Clearly oak-dominated woods here. Bark is white oak.

Evergreen oak leaves, hickory (leaves and nuts), sweetgum fruits, etc. Helps narrow down the ID for logs missing bark.

How to store and ship Stereum

  • Make sure they are fully dry
    • Usually air drying works fine, but using a food dehydrator on low (~90F) until cracker-dry is always a good call. They should store well for a long time.
  • Collections should be kept in plastic bags or paper packets.
  • Make sure each collection is labeled, at minimum, with an iNaturalist observation number. Collector’s name, location, date, ID, etc. is all relevant info that can be included with each collection.
  • Small box or padded envelope is appropriate for shipping depending on how much there is.
  • Contact me for an address if you are interested in contributing! If you are outside the US, please hold on to collections for now and I will get back to you.

I’d love to help! :heart::mushroom: I’m in southeast Texas.

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Cool! I’m curious, what is the best way to preserve fungus specimens, e.g. for sending, DNA sequencing, and/or or just for storage and eventual identification? Dried? Alcohol?

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Good question! For Stereum, the best and simplest way to preserve is dried, and stored either in a paper packet or plastic bag, basically the procedure you would follow for herbarium specimens. It can be trickier to reduce DNA degradation in more delicate fungi (some good info here https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3505157/) but I’ve found Stereum to be really easy to work with, as they are naturally resistant to desiccation.


Glad to help. They are fruiting in Oregon now.

This is great, looking forward to hearing more about the Stereum ostrea story in the East. Have you reported on your preliminary study elsewhere?

I’m really more interested in knowing about what is in the circle and rarely get out of it, so I probably won’t be able to contribute much, but I will be happy to look for interesting stuff and tag this study on here once I clear the COVID-crush backlog from my area.

Yes I’ve put up my preprint on bioRxiv (https://www.biorxiv.org/content/10.1101/2020.10.16.342840v2) and have submitted it to Mycologia, so hopefully it will be published soon! The only species I don’t have in that phylogeny that exists in our “circle” is S. ochraceoflavum. This is a pretty good resource: https://www.mycoguide.com/guide/fungi/basi/agar/russ/ster/ster1

https://www.inaturalist.org/observations/34994354 This is the only Stereum I have sequenced.

I have a bunch of sequences from New Zealand collections of ‘vellereum’, ‘ostrea’ and sanguinolentum. The collections are in PDD. I should get around to depositing the sequences in GenBank.

Yes that would be so super helpful! I would love to examine those sequences, I assume ITS? Do these collections have any field photos as well?

Last reply, lol.

Sarah now has the NZ sequences and a pointer to our national collections online which have the photos. Several people have promised to collect over the next few months as our foray season ramps up. We have a bunch of Australasian names long-buried in synonymy some of which probably need resurrecting. Hopefully the NZ angle will provide something different. It usually does.

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Yes I am so excited! For anyone curious, New Zealand specimens of S. ostrea (or what have been getting called S. versicolor) fall into the same clade as S. lobatum, S. fasciatum, and S. subtomentosum, but represent a distinct species, based on ITS phylogenetic analysis. I think they may represent S. concolor (described from Tasmania), but I’m not sure yet.

Also, since I cannot edit my original post, I will mention it here: for anyone outside the US who would like to help me acquire new collections of Stereum, the best way to do that will probably be to submit your collections to your local herbarium where I can then request them on loan. Still, if you want to help, get in contact with me!

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