Observation 139637: Hypocreopsis rhododendri Thaxt.

When: 2013-07-12

Collection location: Spruce Knob, West Virginia, USA [Click for map]

Who: Taylor (mycogypsy)

Specimen available

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second record for WV
By: mitchell
2013-10-30 18:58:18 PKT (+0500)

This is the second record of H. rhododendri in WV. Nutall originally identified a collection as H. riccoidea and published it in the Flora of West Virginia(1896). It was then identified as H. lichenoides and subsequently annotated by Amy Rossman as H. rhododendri. It is in the US National Fungus Collection and is another example of the value of herbaria. Great find!

Hypocreopsis lichenoides BPI 631883
Kalmia latifolia
United States – West Virginia. Fayette Co., alt. 2000 ft
Coll: Nuttall L. W. ((567) 1178) on 1893 AUG 24
Annotations: Annotated by Amy Rossman on 1993 Mar 10 as Hypocreopsis rhododendri
Other herbaria: Flora of Fayette County W. VA. Nuttall

growing on?
By: Taylor (mycogypsy)
2013-08-09 13:59:09 PKT (+0500)

I believe there is some wood/bark material with the collection. I can check when I return from China.

What was it growing on?
By: Nathan Wilson (nathan)
2013-08-08 01:48:42 PKT (+0500)

Great news! Is it known what it was actually growing own? I understand that it (and it’s host) grow on a number of different plants, so it would be interesting to know what this one was actually growing on.

nice resolution to a myco-puzzle!
By: Debbie Viess (amanitarita)
2013-08-07 20:51:29 PKT (+0500)
By: Katherine Grundy (Katherine.grundy)
2013-08-07 16:37:47 PKT (+0500)

I can confirm that this is indeed Hypocreopsis rhododendri, based on spore morphology and DNA sequence data. Wonderful news!

By: Irene Andersson (irenea)
2013-07-19 13:59:56 PKT (+0500)

But I also beleive that H. rhododendri could have a wider distribution than known so far – easily overlooked because lichenoides is the better known species.
Its host, Pseudochaete corrugata, is more common where the climate is oceanic, but is not restricted to that, and it occurs in North America too.

I’d look pale if I saw a mycologist approaching me with a knife and a sample bag ;)
By: Katherine Grundy (Katherine.grundy)
2013-07-19 02:02:35 PKT (+0500)

Hi Irene,
In my experience, very fresh growth of H. rhododendri tends to be quite pale – if you get a warm, wet spell you’ll often see the tips of the lobes have put on a growth spurt, which appears paler than the rest of the stroma. So this specimen looks to me like it’s grown pretty quickly in prolongued warm, humid weather, which would be consistent with the fact that it’s not showing any grazing damage.
You can also tell it’s not overwintered, as the centre of the stroma looks healthy: in Scotland, at least, overwintered tissue blackens, and grazed overwintered stromata look black and white. Stromata can survive for over a year, in rare cases for more than two years, with the healthy orange tissue around the margin and the blackened tissue in the centre (the photo on H. rhododendri’s wikipedia page is an example of an overwintered stroma).
I’m not sure whether H. lichenoides ever gets as pale or as bright orange as H. rhododendri: I’ve not met it in the field myself, but all of the photos I’ve seen look browner. It could just be that H. lichenoides tends to be drier than H. rhododendri when photographed.
Best regards,

Hide and seek
By: Katherine Grundy (Katherine.grundy)
2013-07-19 01:41:53 PKT (+0500)

Hi Debbie,
Hypocreopsis rhododendri actually has a very close relative, Hypocreopsis amplectens, that also favours an oceanic climate. Hypocreopsis amplectens is found in Australia and New Zealand, and it was only discovered twenty years ago. So I wouldn’t put it past H. rhododendri to get to the western US and avoid detection until now! Who knows, there could be more Hypocreopsis species lurking in scrub, waiting to be discovered…
Best regards,

Other Hypocreopsis species?
By: Irene Andersson (irenea)
2013-07-19 01:35:13 PKT (+0500)

I haven’t seen any pictured Hypocreopsis this pale and yellow. It has to exist more alternatives than lichenoides and rhododendri…

on the other hand…
By: Debbie Viess (amanitarita)
2013-07-19 01:19:04 PKT (+0500)

some of the San Francisco Bay Area DOES have a maritime climate, and the temperate Sonoma and Mendocino coasts have both native rhododendrons and a maritime climate!

But of course, it is quite rare for us on the west coast to share fungi (or many tree species) with Europe and the east coast, unless it has been deliberately introduced.

Still, something else to look out for when hiking Kruse Rhodo Dell this fall.
We’ll keep you appraised, Katherine.

By: Nathan Wilson (nathan)
2013-07-18 06:47:21 PKT (+0500)

Very encouraging. I will definitely keep my eyes open for it. You’ll note that I copied most of your last comment to the Hypocreopsis page so it doesn’t get lost in the shuffle.

Looks at the definition of “oceanic climate” on Wikipedia (https://en.wikipedia.org/wiki/Oceanic_climate) it looks like Cape Cod doesn’t have that climate (and instead is a “humid continental climate” – specifically Dfa or Dfb using Köppen). However, it is surrounded by salt water so who knows.

Probably not all that rare, it’s just surprisingly good at hiding
By: Katherine Grundy (Katherine.grundy)
2013-07-17 06:10:47 PKT (+0500)

Hi Nathan,

Thanks for the email, and my apologies for the delay in replying – I’ve been tied up analysing population genetic data for, you guessed it, Hypocreopsis rhododendri! In answer to your questions:

- “How common is Hypocreopsis lichenoides in the US?”

I’m afraid I don’t know how many records there are for H. lichenoides in the US. I expect it’s under-recorded anyway. To quote Henning Knudsen when I asked him about how common he thought H. lichenoides might be:
“Personally I will assume that it is common in the northern hemispheres temperate, boreal and subarctic zones, because the habitat is common and the host is common”

- “Is this simply something that is small and grows in a place mushroom collectors don’t usually go or is it as rare as it seems to be?”

Hypocreopsis stromata are actually pretty large (generally about 3-10 cm diameter ish, but they can be bigger), they’re bright orange when they’re wet, they’re present all year round and they often conveniently grow at eye level. In spite of this however, they do seem to have a history of being overlooked. The reason for this, as you suggested, is probably the lack of overlap between the niche of Hypocreopsis species and the niche of Hypocreopsis: the latter tends to like growing on multi-stemmed shrubs, whether climax scrub or understory vegetation. To quote Henning Knudsen again:
“The problem with the frequency of H. lichenoides is the fact that it occurs in habitats that are rarely investigated (I rarely meet colleagues in the middle of a moist, dense Salix scrub!).“

-“What to the best of your knowledge is the range and habitat of the genus in the US?”

Hypocreopsis rhododendri has been found at a few sites along the narrow band of oceanic climate that runs through the Appalachians (see https://en.wikipedia.org/...). This species is also restricted to a strongly oceanic climate in Europe, so if it occurs anywhere in the USA besides the Appalachians, it’s highly likely that it will be somewhere with an oceanic climate.
Hypocreopsis lichenoides is much less, if at all, oceanically restricted, and seems to be tolerant of colder conditions than H. rhododendri. It’s pretty widespread across the northern US and Canada: I’m aware of records of the species from New Hampshire, Washington and Idaho, and north of the border, Quebec, Ontario and Sept-Îles. There is also a record of Hypocreopsis from Maine, and although it was originally determined as H. rhododendri, the collection doesn’t have mature spores so it isn’t possible to confirm the species ID – my suspicion is that this record is actually H. lichenoides. I expect there are also further records of H. lichenoides from North America: I’m afraid I’ve not been as meticulous in digging out H. lichenoides records as I have for H. rhododendri.
Hypocreopsis species are parasites of the twig-binding, wood rotting genus Pseudochaete (recently split from Hymenochaete). Hypocreopsis rhododendri parasitises Pseudochaete corrugata; H. lichenoides parasitises Pseudochaete tabacina.
In terms of tree / shrub species, in Europe H. rhododendri is found mainly on Corylus avellana, but in the USA it’s been found on Rhododendron maximum, Quercus sp. and Kalmia latifolia. In Europe H. lichenoides is found mainly on Salix spp., and it seems to have been recorded on all sorts of stuff in N America, including, but not restricted to, Ulmus Americana, Corylus rostrata, Rhus typhina, Acer spicatum and Lonicera sp.

-“Any reasonable chance I might find this locally?”

Considering the H. lichenoides record from New Hampshire, I wouldn’t be at all surprised if it’s also present in Massachusetts. As for H. rhododendri, how oceanic is the Cape Cod climate?
Your best bet for finding Hypocreopsis is finding a site with a really healthy population of Pseudochaete. Although the fruiting crusts and glued twigs of Pseudochaete species are less conspicuous than Hypocreopsis stromata, they’ll be more abundant than the Hypocreopsis.

I hope you do encounter it: it’s a really striking genus.

Best regards,

By: Taylor (mycogypsy)
2013-07-14 06:57:19 PKT (+0500)

Hi Katherine,
Send an address. I’ll send you something.

another good reason…
By: Debbie Viess (amanitarita)
2013-07-13 20:31:35 PKT (+0500)

to bring home samples of our more interesting finds. ;)

I hope that you get your chance to check this material, Katherine.

The clues as to it being H. rhododendri are tantalizing.

How common is Hypocreopsis lichenoides?
By: Nathan Wilson (nathan)
2013-07-13 19:30:28 PKT (+0500)

Hi Katherine,

This is the first I’m learning about this genus. How common is Hypocreopsis lichenoides in the US? As I mentioned the only records on MO are two from Europe and both were found by very experienced MO users. Is this simply something that is small and grows in a place mushroom collectors don’t usually go or is it as rare as it seems to be (note that we have 5 observations of Bridgeoporus nobilissimus on the site). What to the best of your knowledge is the range and habitat of the genus in the US? I live on Cape Cod in Massachusetts near several Atlantic White Cedar swamps as well as other swamps that have a native azalea (Rhododendron viscosum) as well as native hazels (Corylus cornuta) and Kalmia angustifolia. Any reasonable chance I might find this locally?

Is this the first record of H. rhododendri in 100 years?!
By: Katherine Grundy (Katherine.grundy)
2013-07-13 17:23:49 PKT (+0500)

Hi Taylor (mycogypsy),
This is an incredibly exciting find – I’m doing a PhD on this species, and I’ve been trying to track down USA records for Hypocreopsis rhododendri, but nobody is aware of any sightings since ~1900. If your fungus is Hypocreopsis rhododendri, and not the macroscopically indistinguishable Hypocreopsis lichenoides, it will be confirmation that the species isn’t extinct in North Amercia, which would be fantastic news.

From the photo it looks as though it might be growing together with Hymenochaete corrugata, which would be typical for H. rhododendri (Hypocreopsis lichenoides is found with Hymenochaete tabacina).

I don’t suppose you are able to take a sample of the perithecia of the Hypocreopsis sp., are you? It would be great to get a look at the spores in order to determine which Hypocreopsis species it is.

Also, if you are able to get a tissue sample, I’d be really, really interested in DNA sequencing it, in order to discover how the North American H. rhododendri population is related to the European population. A few lobes would be more than sufficient for DNA extraction (you have to be careful when sampling Hypocreopsis species not to take the too much of the stroma, as the stroma isn’t just a fruiting structure, it’s the entire body of the fungus).

Thanks for sharing your find!
Katherine Grundy
PhD student
University of Aberdeen (Scotland)

From Wikipedia…
By: Nathan Wilson (nathan)
2013-07-13 02:11:17 PKT (+0500)

“Pre-1920 records also exist for H. rhododendri from the Appalachian mountains in the eastern United States,2 but it is not known whether it remains extant in this region.”


This could be quite a find!

Apparently a rare genus…
By: Nathan Wilson (nathan)
2013-07-13 02:02:59 PKT (+0500)

Awesome photo and observation. Assuming this is a Hypocreopsis (which seems likely), my understanding from the two other observation of this genus in MO (both European) is that this is a rare find and if possible a voucher specimen of it would be very helpful. Also please try to identify whatever type of plant it is growing on and note (hopefully with photos and samples) any crusts (particularly in the genus Hymenochaete: http://mushroomobserver.org/observer/observation_search?pattern=Hymenochaete) that are growing on the plant as well.

Created: 2013-07-13 00:14:35 PKT (+0500)
Last modified: 2013-10-30 22:58:54 PKT (+0500)
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