Leucocoprinus cretaceus and the Complications of Identifying Leucocoprinus Species After Heavy Rainfall

Like other scaly mushrooms such as Amanita and Chlorophyllum species, the appearance of the caps of certain Leucocoprinus species are prone to much change as a result of these scales washing away in rain. A good demonstration of this is Leucocoprinus cretaceus since it is quite distinct and retains characteristics that often enable it to be identified without too much confusion even after heavy rainfall. For instance in this photo we can see that the caps have largely become smooth with only the center scales being retained. White debris from the caps is visible on the wood below, as is the dry spot on the wood where it has been sheltered by the caps. Also sheltered are the stems which have retained their distinctive white scales.

Observation 138735331 - Leucocoprinus cretaceus after rainfall Credit: @geovane_siqueira

Despite losing some of their distinctive features it is still clear that these mushrooms are Leucocoprinus cretaceus, however for other Leucocoprinus species rainfall may pose a greater issue for identification and result in them looking like another species.

The species most commonly confused with Leucocoprinus cretaceus on iNaturalist appears to be Leucocoprinus cepistipes. The two are similar with both displaying clustered, caespitose growth behaviour often on woodchips, rotting wood or compost. Both species have some degree of white scales on the caps, however these are far more pronounced and warty on L. cretaceus and much finer on L. cepistipes. Additionally L. cepistipes has a distinct, brownish central disc which is broadly umbonate in immaturity and a smooth stipe that is often prone to clear exudation collecting towards the base. These droplets can be mistaken, at a glance (or by the image recognition app) for the scaly white stem base of L. cretaceus. L. cretaceus can display some brown or yellowish discolouration at the centre of the cap and the white coating may rub off the stipe revealing a brownish or yellowish surface which may result in confusion with L. cepistipes.

When rainfall removes the features of either species they can more closely resemble each other and are easier to mistake. The caps of both are prone to splitting as they become heavily saturated resulting in scales and white debris from the cap littering the ground around. Additionally a slight brown tone at the centre of the cap on Leucocoprinus cretaceus may become more noticeable.

Observation 86218038 - Soggy L. cepistipes Credit: @churley_25

Observation 73094381- Soggy L. cretaceus Credit: @hughianni

Leucocoprinus cretaceus

There is a possibility that observations for L. cretaceus may include a number of more obscure, less well known species. For instance Leucocoprinus elaeidis and Leucocoprinus nanianae are described very similarly but note some yellow discolouration. The spore sizes described for all three species are virtually identical however and it seems likely that these may just be synonyms that have yet to be reclassified due to them being forgotten in such obscure books. No information exists for either online beyond the initial description and some old sketches for L. elaeidis and their listings in Mycobank and Species Fungorum as current species.

The book L. nanianae was described in turned out to be so uncommon that in the end I only managed to find it by reaching out to a rare book shop in France which happened to have a copy so I am très grateful to Etienne at Arcala Livres Anciens for the assistance in sending me photos. It is of course very likely that plenty of organisations do hold this book although I did note that every species described in it lacks any information online so it may indeed be rare. Due to the entirely broken copyright system we have which stipulates that work arbitrarily remains in copyright until 70 years after the authors death, the Biodiversity Heritage Library only have digitised volumes of Bulletin de l'Académie Malgache up to 1925. These nonsensical laws driven solely by corporate greed result in old, boring scientific texts which are not in print, will never again be put in print or turn a profit for the likely dead authors (and often defunct organisations) being essentially hidden from the world for absolutely no reason. A constant thorn in my side when attempting to research these old species is finding that Google books has a fully digitised and searchable copy of the book online but will not let me see it because 'it is still in copyright' with any requests for content being ignored. But I digress...

Leucocoprinus breviramus also has some similarities to L. cretaceus in the description but enough that it might be possible to distinguish it from L. cretaceus. This species was more recently described and was compared to L. cretaceus so does seem likely to be distinct and there are possibly some observations of it on iNaturalist which need exploring. Hopefully by collecting everything that appears to be L. cretaceus in one place it will become easier to find distinctions. Already I have collected a number of observations together which I am not satisfied to just identify and dismiss as L. cretaceus which I suspect may be L. breviramus or another species due to the excessively floccose details.

Other mushrooms that are often mistaken for L. cretaceus by the image recognition algorithm include some members of Amanita sect roanokenses, some of the white, scaly Leucoagaricus, Chlorophyllum and Cystolepiota species and some puffballs. These are generally simple enough to separate out under normal circumstances however when very immature or when rainfall has removed cap features these species are likewise easier to confuse.

Leucocoprinus cretaceus without rain damage

Observation 26249347 Credit: @teodoro_chivatabedoya | Observation 26249347 Credit: @teodoro_chivatabedoya | Observation 68176921 Credit: @hughianni | Observation 139959458 Credit: @loonathegarden

Leucocoprinus cretaceus after rain

Observation 51654912 Credit: @conservation_partnerships_ipswich | Observation 132191704 Credit: @parahuaco | Observation 112907030 Credit: @markwheatley | Observation 139959098 Credit: @loonathegarden

Publicado el noviembre 18, 2022 05:21 TARDE por mycomutant mycomutant


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