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Melanoleuca castaneofusca new to Britain
K$&O&PNQ
Melanoleuca castaneofusca new to Britain #$%# & F n October 2012 Ted Brown brought me a collection of a tricholomatoid fungus he had found in Morden Cemetery, Surrey, growing on composted soil (Fig. 1). Its very dark, rounded caps had noticeably darker, droplet-like spots around the margin and hence were reminiscent of Lepista panaeola—well known for this character. But that species is much paler, with pinkish white gills and pleasant fruity odour. The caps of Ted’s collection also had a white pruinosity which increased as they dried and the stem was strongly woolly-fibrillose. The gills were greyish white and sinuate-adnate and the whole suggested that it might be a species of Melanoleuca. This was confirmed when microscopic examination revealed the characteristic harpoon-like cheilocystidia and ornamented spores so typical of that genus (Fig. 2).
Once the genus was established there came the more difficult task of trying to assign it to a species; Melanoleuca remains one of the most complex and difficult genera with a large number of described species. Added to this profusion of names is the difficulty of deciding which literature to follow; almost every author has their own interpretation of the various species. Extensive DNA analysis to clarify the classical species, along with those more recently described, is badly needed, perhaps with epitypification where required and the first steps towards this have now been made (Vizzini et al. 2011). So a search through the literature to try and identify this collection was always going to be difficult. It was obvious that it did not agree with any of the better known species but that still left a large number of lesser known species to
I
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doi:10.1016/j.fldmyc.2016.07.007
1$
K$&O&PNQ for his opinion. We both agreed that if possible such an important and tricky identification should be confirmed by a molecular analysis. The material was given to Laura Martinez-Suz at Kew who managed to extract the necessary molecular (ITS) sequence. It then needed to be compared with the sequence of M. sublanipes and others if possible. By a fortuitous coincidence Martyn remembered that mycologist Vladimir Antonin was about to give a talk on European Melanoleuca at the XVII Congress of European Mycologists in Madeira and sent the resulting sequence to him. Antonin and his colleague M. Tomsovsky were able to run a comparison on the sequence and came back with an unequivocal result: it was not M. sublanipes but instead another recently described species, M. castaneofusca Contu. M. castaneofusca was described from Sardinia by Marco Contu (1998), growing on sandy soils close to cacti, which seems a long way from a compost heap in a Surrey churchyard! It wouldn’t be the first time however that an invasive species has turned up in Britain and adapted to a different climate and habitat, there are several current examples on woodchip mulch for example. Contu describes M. castaneofusca as having a chestnut brown cap with a blackish bistre centre, with whitish, moderately crowded gills and a white, sub-bulbous stem which is fibrillose-striate. Spores are 6–7.5 x 4.5–5.2 µm. Cheilocystidia are 18–48 x 7–8.2 x 2–3 µm, often septate. Much of this description matches the Surrey collection but some macroscopic features differ: the British collection has a distinctly grey, strongly felty-pruinose stem, the cap has more greyish-bistre colours rather than chestnut and the gills have a pale grey tint. Microscopically it is in strong agreement with the Sardinian material. The macroscopic differences could well be explained by the cooler, wetter climate here as well as a wetter, richer substrate.
septum
cheilocystidium
spore
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compare. The structure of the cheilocystidia is of considerable help in dividing up the species in Melanoleuca. In one group they are fusoid-ventricose without a dividing basal septum while in the other they are much more slender with a basal septum separating the apical portion from the swollen base, usually referred to as urticoid (like the sting of Urtica dioica, the common Stinging Nettle). The cystidia of Ted’s collection were of the latter sort (Fig. 2). The spores of Melanoleuca are ellipsoid with amyloid warts (staining black in Melzer’s Iodine solution) and their size and amount of ornamentation are also of importance in identification (Fig. 2). The spores here were ellipsoid, 6–7 x 4.5–5 µm, with rather scattered, large warts which stained strongly in Melzer’s solution. Once these characters were ascertained attempts were made to key out the species in the available literature (Funga Nordica, Moser’s Keys to Agarics & Boleti, Fungi of Switzerland, British Fungus Flora etc) but to no avail, none seemed to fit exactly. A search was begun therefore through the many mycological journals held in the BMS and Kew libraries, as well as online and a possible candidate soon came to light: Melanoleuca sublanipes Fontenla, Para & Vizzini. Many of its features seemed to match very well and this became my first tentative identification. If it was this species then it would be new to Britain. And this was where matters stood until I handed the material to Martyn Ainsworth at Kew and asked
Other British collections? During discussions over a book he is working on, Andy Overall happened to show me a photograph of a collection he had made of a Melanoleuca in Kensington Gardens and I was immediately struck by the similarity with Ted’s material (Fig. 3). It had similar very dark bistre-blackish caps and a strongly felty-pruinose stem. Material has been sent to Kew but has not yet been prepared
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for DNA sampling. So for the moment it remains undetermined but seems a likely candidate for M. castaneofusca. A third similar collection—this time by David Warwick—made in Victoria Park, London E3 on 18th October 2015, was found growing on soil along an open shrub border (Fig. 4). It has paler, greyer colours (but is obviously dryer which in most Melanoleuca species always results in the cap colours fading) and very clearly has the darker spots around the cap margin. Material has not been examined so this too must remain a tentative identification at best but it is certainly intriguing. I would urge readers who find similar
collections to take good photos, dry their material and feel free to contact me; M. castaneofusca may turn out to be an increasingly common species in urban habitats in Britain.
References Contu, M. (1998). Une nouvelle espèce de Melanoleuca (Basidiomycota) de la Sardaigne, avec notes sur la taxonomie du genre. Bull. Féd. Myc. Dauphiné-Savoie 150: 41–43. Vizzini, A. et al. (2011). A preliminary ITS phylogeny of Melanoleuca (Agaricales), with special reference to European species. Mycotaxon Vol. 118: 361–381.
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10
Melanoleuca castaneofusca new to Britain #$%# & F n October 2012 Ted Brown brought me a collection of a tricholomatoid fungus he had found in Morden Cemetery, Surrey, growing on composted soil (Fig. 1). Its very dark, rounded caps had noticeably darker, droplet-like spots around the margin and hence were reminiscent of Lepista panaeola—well known for this character. But that species is much paler, with pinkish white gills and pleasant fruity odour. The caps of Ted’s collection also had a white pruinosity which increased as they dried and the stem was strongly woolly-fibrillose. The gills were greyish white and sinuate-adnate and the whole suggested that it might be a species of Melanoleuca. This was confirmed when microscopic examination revealed the characteristic harpoon-like cheilocystidia and ornamented spores so typical of that genus (Fig. 2).
Once the genus was established there came the more difficult task of trying to assign it to a species; Melanoleuca remains one of the most complex and difficult genera with a large number of described species. Added to this profusion of names is the difficulty of deciding which literature to follow; almost every author has their own interpretation of the various species. Extensive DNA analysis to clarify the classical species, along with those more recently described, is badly needed, perhaps with epitypification where required and the first steps towards this have now been made (Vizzini et al. 2011). So a search through the literature to try and identify this collection was always going to be difficult. It was obvious that it did not agree with any of the better known species but that still left a large number of lesser known species to
I
"& "& ! ! !& $& #& %J#%!& %$#@J#& $& %$ & #& & %"& M$%# H# ##% !& %%# !&7 $ #%&"& $$% &&#$%# & " F&# $6 $$" $" J
doi:10.1016/j.fldmyc.2016.07.007
1$
K$&O&PNQ for his opinion. We both agreed that if possible such an important and tricky identification should be confirmed by a molecular analysis. The material was given to Laura Martinez-Suz at Kew who managed to extract the necessary molecular (ITS) sequence. It then needed to be compared with the sequence of M. sublanipes and others if possible. By a fortuitous coincidence Martyn remembered that mycologist Vladimir Antonin was about to give a talk on European Melanoleuca at the XVII Congress of European Mycologists in Madeira and sent the resulting sequence to him. Antonin and his colleague M. Tomsovsky were able to run a comparison on the sequence and came back with an unequivocal result: it was not M. sublanipes but instead another recently described species, M. castaneofusca Contu. M. castaneofusca was described from Sardinia by Marco Contu (1998), growing on sandy soils close to cacti, which seems a long way from a compost heap in a Surrey churchyard! It wouldn’t be the first time however that an invasive species has turned up in Britain and adapted to a different climate and habitat, there are several current examples on woodchip mulch for example. Contu describes M. castaneofusca as having a chestnut brown cap with a blackish bistre centre, with whitish, moderately crowded gills and a white, sub-bulbous stem which is fibrillose-striate. Spores are 6–7.5 x 4.5–5.2 µm. Cheilocystidia are 18–48 x 7–8.2 x 2–3 µm, often septate. Much of this description matches the Surrey collection but some macroscopic features differ: the British collection has a distinctly grey, strongly felty-pruinose stem, the cap has more greyish-bistre colours rather than chestnut and the gills have a pale grey tint. Microscopically it is in strong agreement with the Sardinian material. The macroscopic differences could well be explained by the cooler, wetter climate here as well as a wetter, richer substrate.
septum
cheilocystidium
spore
"& "& & ##& $& ! $& % $& #$ & & $% ##& $%#" ; & $& $& #& #& %& 5& & 1 "& $$& #$%# & "
compare. The structure of the cheilocystidia is of considerable help in dividing up the species in Melanoleuca. In one group they are fusoid-ventricose without a dividing basal septum while in the other they are much more slender with a basal septum separating the apical portion from the swollen base, usually referred to as urticoid (like the sting of Urtica dioica, the common Stinging Nettle). The cystidia of Ted’s collection were of the latter sort (Fig. 2). The spores of Melanoleuca are ellipsoid with amyloid warts (staining black in Melzer’s Iodine solution) and their size and amount of ornamentation are also of importance in identification (Fig. 2). The spores here were ellipsoid, 6–7 x 4.5–5 µm, with rather scattered, large warts which stained strongly in Melzer’s solution. Once these characters were ascertained attempts were made to key out the species in the available literature (Funga Nordica, Moser’s Keys to Agarics & Boleti, Fungi of Switzerland, British Fungus Flora etc) but to no avail, none seemed to fit exactly. A search was begun therefore through the many mycological journals held in the BMS and Kew libraries, as well as online and a possible candidate soon came to light: Melanoleuca sublanipes Fontenla, Para & Vizzini. Many of its features seemed to match very well and this became my first tentative identification. If it was this species then it would be new to Britain. And this was where matters stood until I handed the material to Martyn Ainsworth at Kew and asked
Other British collections? During discussions over a book he is working on, Andy Overall happened to show me a photograph of a collection he had made of a Melanoleuca in Kensington Gardens and I was immediately struck by the similarity with Ted’s material (Fig. 3). It had similar very dark bistre-blackish caps and a strongly felty-pruinose stem. Material has been sent to Kew but has not yet been prepared
1(
K$&O&PNQ
"&N"&L& ! # #& $#%#&$&$$ & &&#$& %#!&7 $ #%&I"& $$% &L &7#% "
for DNA sampling. So for the moment it remains undetermined but seems a likely candidate for M. castaneofusca. A third similar collection—this time by David Warwick—made in Victoria Park, London E3 on 18th October 2015, was found growing on soil along an open shrub border (Fig. 4). It has paler, greyer colours (but is obviously dryer which in most Melanoleuca species always results in the cap colours fading) and very clearly has the darker spots around the cap margin. Material has not been examined so this too must remain a tentative identification at best but it is certainly intriguing. I would urge readers who find similar
collections to take good photos, dry their material and feel free to contact me; M. castaneofusca may turn out to be an increasingly common species in urban habitats in Britain.
References Contu, M. (1998). Une nouvelle espèce de Melanoleuca (Basidiomycota) de la Sardaigne, avec notes sur la taxonomie du genre. Bull. Féd. Myc. Dauphiné-Savoie 150: 41–43. Vizzini, A. et al. (2011). A preliminary ITS phylogeny of Melanoleuca (Agaricales), with special reference to European species. Mycotaxon Vol. 118: 361–381.
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%& %#& # % & #"& $$% &&: &C % J"
10