Porostereum spadiceum (Pers. : Fr.) Hjortstam & Ryvarden

Excluded. What I thought was a species with no recent records turned out to be one with no correct historic records. That history of investigation for 2014 to 2018 follows:

This species was described in Moffatt (1909) but I had never identified it. In August 2014, I started assembling this page as an example of a species that had no recent records. When researching taxonomy and records online I thought that photos of it resembled an unknown stereum-like fungus I had found recently but the microscopic characters were quite different; it turned out to be Punctularia strigosozonata.

A few days later I looked through the Field Museum herbarium (F) collections and discovered that Harper's Chicago specimens and most of the U.S.A. collections of early collectors from 1887 to 1914 (including Fungi Columbiani exsiccatae) are misidentified and many seem to be Stereum gausapatum; most are labeled as being on oak. The Harper collection from Glencoe IL has both names on the original label with an equal sign suggesting they are synonyms. But Harper and others also have different specimens labeled correctly as Stereum gausapatum.

Both species are described in Moffatt (1909) but Stereum spadiceum is the one described as bleeding red if bruised, not Stereum gausapatum. So it seems the concepts were confused. Many BPI herbarium collections (on MyCoPortal) were identified by C.G. Lloyd as Stereum spadiceum. Herbarium specimens require microscopic examination to sort out their identities.

Next, I searched online regarding the exsiccatae of Stereum spadiceum, and this led me to the work of Lentz (1955), a copy of which I had luckily obtained two weeks prior. Lentz examined the Fungi Columbiani exsiccatae (see page 53) and found that numbers 2589, 2883, 4292, 4987, 5092 are all Stereum gausapatum; the same set of five I examined earlier in the day at the Field Museum. So this problem had already been sorted out but the findings of Lentz had not been applied to our collections. Lentz worked with specimens from many herbaria of America and Europe but unfortunately not those of the Field Museum.

Ryvarden (2010) describes four Porostereum species from Cuba, Mexico, and South America. He equates the type P. phellodendri Pilát with Thelephora spadicea Pers.:Fr. but does not treat it in his book and does not indicate any species existing in USA or Canada. This gave another clue that Porostereum spadiceum may not actually occur in the USA.

Update May 2018: Liu et al. (2018) say that Porostereum spadiceum is known from Europe, Armenia and Morocco. It seems most likely that the many USA and Canada specimens labeled Stereum spadiceum from 1848–1942 are all missapplied identications. The few collections on MyCoPortal from 1999–2014 (all as Stereum spadiceum) are most likely data errors and represent 1899–1914 (this is a frequent problem on MyCoPortal). There is only one modern Porostereum spadiceum collection; it is from 2008 in West Virginia and this identification should be verified. There are no observations of current Porostereum species on Mushroom Observer (as of May 2018), other than some from Austria and Portugal, which are listed as the synonym Lopharia spadicea.

Update July 2018: Mycobank indicates that Porostereum spadiceum was not sanctioned by Fries but rather that a different taxon Stereum spadiceum Fr., Epicrisis Systematis Mycologici: 549 (1838) is sanctioned as Thelephora spadicea Fr., Elenchus Fungorum 1: 176 (1828) and this is a synonym of Thelephora gausapata Fr., Elenchus Fungorum 1: 171 (1828) [= Stereum gausapatum]. Perhaps this was the major cause of confusion between Stereum gausapatum and Porostereum spadiceum.