- Email: [email protected]
Notes & Records
D" ##FE
Notes & Records B ?#> ! A
O
nce more these notes somewhat resemble the dessert course that Winston Churchill is said to have rejected with the words “This pudding has no theme.” No theme here either - just sundry personal musings on disparate topics, apart from the first item which was held over from the last issue for lack of space.
photos are concerned H&L currently include around 230 species (with promise of more to come by email to purchasers). B&G have in total 25% more species with photos, but only around 200 of these are known in Britain. They often have two (or even three) contrasted illustrations of the same species, some garishly coloured, but a useful reminder of how few can be named with confidence on field characters alone. The slightly larger H&L selection of British species are all much more natural-looking field shots. But also a further warning: the frequencies assigned in H&L can be misleading. They are defined on p.5 and relate purely to records made in Hampshire. Further remarks on their interpretation are said to be contained in the preface but haven’t reached the printed version. Some make strange reading in any wider context. There is little doubt that the conspicuous pink Aleurodiscus wakefieldiae is a national (and indeed international) rarity but in Hampshire (the New Forest) it is indeed merely ‘Uncommon’. Conversely numerous species that form small thin white patches are said to be ‘Rare’ or ‘Very rare’, giving these probably merely underrecorded species more significance than they deserve.
Sequencegate - the upshot It may be remembered from my account in FM19(3) that a proposal was then about to be made to the IMC (International Mycological Congress) to allow new fungal species to be defined based on a DNA sequence alone. It wasn’t expected to be accepted in the form it then took, but even if it was it would only come into force following the next International Botanical Congress at Rio in 2023. I predicted that, in a manner reminiscent of Brexit negotiations, this can would get kicked down the road. This has indeed happened. A working group was set up. It is hoped that this will put the proposal into a form with a better chance of gaining acceptance at the next IMC in 2022. If that hurdle is crossed it will still be in time for Rio 2023 where, as an issue of purely fungal relevance, it will be automatically adopted.
Are these spores smooth? Two people have recently sent me collections to identify or confirm because the thing they had keyed it out to seemed to be unknown in Britain (in one case) or merely rare (in the other). Sure enough this is where their observations took them but the verdicts reached seemed highly implausible and rather poorly fitting in other respects - in short wrong! In each case the wrong direction taken in the keying process turned out to concern the spores, assumed smooth at x400 but in fact warted, showing up fairly clearly under oil at x1000, after which the keying process at least becomes smooth, leading in both cases to well-known species. It doesn’t seem to be sufficiently widely appreciated that you cannot be sure at x400 whether there is ornamentation. In
A further plug for The Resupinates of Hampshire No I am not being paid for this, though the authors, Hugill & Lucas (2017) did give me a free copy! It was originally reviewed by Geoffrey Kibby in FM18(2). I am surprised to find how often I consult it. Do they have a picture of what I think I’ve found? And does their nice photo look anything like my material? Do they agree it’s rare? etc. etc. A comparison can be made of the corticioid part of this book with the vastly heavier Bernicchia & Gorjon (2012), though anyone seriously wanting to identify corticioids should get both. Each includes a few genera the other doesn’t consider to be corticioid, but this hardly affects the following rough comparison. As far as
A9#D "! #=" #CJ"H #2"J#2 H"J#CI!! # 7;#@37
doi:10.1016/j.fldmyc.2019.01.012
0'
D" ##FE some species you can’t even be sure under oil and SEM is needed, but the writers of keys for ordinary mortals have sense enough to key these as appearing smooth. They are usually less inclined to provide a safety net for readers who miss ornamentation not clearly visible at x400.
significantly different DNA. The transition didn’t happen overnight, more likely over centuries at least, during which it would have been a matter of taxonomic opinion whether they were one species or two. Ecologists analysing soil samples using highthroughput DNA meet this challenge head-on. Instead of talking species they talk only of OTUs (Operational Taxonomic Units) and note that the numbers of these they record differ vastly according to the percentage of base-pairs required to be different in the ITS region before two OTUs are treated as distinct. In many agaricoid genera currently accepted species tend to exhibit differences of over 3% in their ITS base-pairs. Conversely smaller differences tend not to show up as taxa demanding treatment as separate species. But it isn’t as simple as that. Indignant taxonomists, finding their species synonymised on the grounds of close ITS similarity have been known to retaliate and cite other less fashionable DNA regions in support of their case! Lets throw some speculative numbers into this discussion. Suppose the average fungal species, however defined, has a million year life on earth before going extinct. Suppose also there are 20,000 British fungal species. Then in any century on average two will go extinct, and in a steady-state world (one that hasn’t heard of anthropogenic mass extinctions) two will evolve to species level to replace them. So these two at least will tend to present as ambiguously one species or two. I have met field naturalists who are put off fungal identification from a perception that fungal species are still all one big muddle. But plants have similar problems even if on a smaller scale. Ask a botanist how many Mediterranean orchids should be recognised in the genus Ophrys!
# # G"# " "! # "# # "! # "# &$% ' # # " # " "#I ## <#"% 8 #G ## # # ### " #H " "#<# # "G !#I ## #" # HH ! "# #G # # # # " #H "#"# #J ! # # G ?# "!H "# "# # "! # I!8 # " "! ## "! #
Some remarks on species concepts It is acknowledged that, as discussed above, there is a continuum between smooth and ornamented spores (and indeed between thin- and thickwalled spores which often leave me less certain than the writers of keys appear to be). On similar grounds there cannot always be criteria to decide whether two closely related taxa belong to one species or two. Again there is a continuum involved, that of time, from the past when there was only their common ancestor to some later date by which time they have evolved into two undeniably distinct species, intersterile with
Some thoughts on keys I am thinking here of the usual binary keys. Suppose you have eight species to key, each keying out in one place (thus seven couplets). It would be nice, but seldom practical, to find a first couplet that divides them into two groups of four and further couplets to split each of these into two pairs. In this way the user of the key will always reach their answer after making just three decisions. Too many keys approximate to the other extreme where the first two couplets can read:
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D" ##FE 1. Is it like this? . . . Species A 1* Not so . . . . . . . . . . . . . . . . 2 2. Or like this? . . . . Species B 2* Not so . . . . . . . . . . . . . . . . 3
about and the more difficult ones (spore ornamentation?) only where unavoidable. • Don’t insist on keying each species out at only one place. • Don’t pick out all the distinctive rarities first just because they are easy to key. They only hang up the reader who has to get past them. • So try and lead the user to the commoner species in as few and as easy steps as possible. • In any key that involves microscopy at all it is a good plan to split up awkward groups into ones with spores above or below a certain size. Spore size is usually easily measured. Borderline species must then be keyed both ways. The key to Psathyrella in Funga Nordica is a good example of this technique, reducing a large genus to fairly manageable chunks.
And so it goes till the commonest and least distinctive species is reached in the final couplet after the reader has had six opportunities to go wrong at each earlier choice. This is hardly a key. There are in fact a great many ways of keying eight species, intermediate between these two extremes. Maths unfriendly readers can skip the next paragraph, inserted for my own amusement, where I discuss just how many. There are obviously just three possible ways of keying three species depending on which of the three is singled out in Couplet 1. What about four species? Any one of the four could be keyed out first followed by any of the remaining three second, leaving the other two for the final couplet. That is already 12 possible keys. Then there are the three ways in which couplet 1 could be used to split the four species into two pairs. So 15 in all. Exercise for the reader: ‘Find an iterative proof that the number of possible keys to n species is the product of the first n-1 odd numbers. So with as few as five species there are already 1x3x5x7 = 105 possible keys. For a reasonable sized key to 15 species multiplying up in this way you reach a 15 digit number! Use of Stirling’s formula for approximating factorials shows that thereafter the number of decimal digits in the answer rises faster than the number of species.
Finally a couple of quotes More and more of the fungi I find now seem beyond my ability to identify. There are all those agaric genera where I have lost confidence in any verdict I reach that's out of the ordinary. I find an unfamiliar Entoloma and I know it's going to cause trouble. Identification attempts get postponed. Eventually I discard it unexamined. When others happily name such things I smugly recall a favourite quote I have seen attributed to Darwin "Ignorance more frequently breeds confidence than knowledge". Not altogether fair of course - some few people do know what they are doing! Another quote that appeals to me appears, unattributed, at the front of Para Sanchez' learned two-volume treatise on Agaricus (Fungi Europaei, Vols 1 + la). He or somebody has declared "Experts do not exist, we are all beginners with greater or lesser knowledge." This one nicely sums up for me the current state of fungal identification.
And thoughts on key construction These stem from my long-held belief that many a published key could easily have been made much more user-friendly with only a little more thought. The aim of the writer of any key should be to maximise the chances of its user arriving at the right species (or, equally important, correctly deciding that their species isn’t covered). To that end some do’s and dont’s: • Don’t go all purist and limit the characters used purely to morphology. • So do mention hosts or habitats or fruiting times or even rarity if any of these help to narrow the choice. • Don’t go overboard trying to make the key match the known phylogeny. • Do use first the easiest characters to be sure
References Hugill, P. & Lucas, A. (2017). The Resupinates of Hampshire. Pixart Printing. Bernicchia, A. & Górjon, S.P. (2010). Corticiaceae s.l. (FE12). Editioni Candusso. Örstadius, L. & Knudsen, H. (2012). Psathyrella. In Funga Nordica. Nordsvamp.
0&
Notes & Records B ?#> ! A
O
nce more these notes somewhat resemble the dessert course that Winston Churchill is said to have rejected with the words “This pudding has no theme.” No theme here either - just sundry personal musings on disparate topics, apart from the first item which was held over from the last issue for lack of space.
photos are concerned H&L currently include around 230 species (with promise of more to come by email to purchasers). B&G have in total 25% more species with photos, but only around 200 of these are known in Britain. They often have two (or even three) contrasted illustrations of the same species, some garishly coloured, but a useful reminder of how few can be named with confidence on field characters alone. The slightly larger H&L selection of British species are all much more natural-looking field shots. But also a further warning: the frequencies assigned in H&L can be misleading. They are defined on p.5 and relate purely to records made in Hampshire. Further remarks on their interpretation are said to be contained in the preface but haven’t reached the printed version. Some make strange reading in any wider context. There is little doubt that the conspicuous pink Aleurodiscus wakefieldiae is a national (and indeed international) rarity but in Hampshire (the New Forest) it is indeed merely ‘Uncommon’. Conversely numerous species that form small thin white patches are said to be ‘Rare’ or ‘Very rare’, giving these probably merely underrecorded species more significance than they deserve.
Sequencegate - the upshot It may be remembered from my account in FM19(3) that a proposal was then about to be made to the IMC (International Mycological Congress) to allow new fungal species to be defined based on a DNA sequence alone. It wasn’t expected to be accepted in the form it then took, but even if it was it would only come into force following the next International Botanical Congress at Rio in 2023. I predicted that, in a manner reminiscent of Brexit negotiations, this can would get kicked down the road. This has indeed happened. A working group was set up. It is hoped that this will put the proposal into a form with a better chance of gaining acceptance at the next IMC in 2022. If that hurdle is crossed it will still be in time for Rio 2023 where, as an issue of purely fungal relevance, it will be automatically adopted.
Are these spores smooth? Two people have recently sent me collections to identify or confirm because the thing they had keyed it out to seemed to be unknown in Britain (in one case) or merely rare (in the other). Sure enough this is where their observations took them but the verdicts reached seemed highly implausible and rather poorly fitting in other respects - in short wrong! In each case the wrong direction taken in the keying process turned out to concern the spores, assumed smooth at x400 but in fact warted, showing up fairly clearly under oil at x1000, after which the keying process at least becomes smooth, leading in both cases to well-known species. It doesn’t seem to be sufficiently widely appreciated that you cannot be sure at x400 whether there is ornamentation. In
A further plug for The Resupinates of Hampshire No I am not being paid for this, though the authors, Hugill & Lucas (2017) did give me a free copy! It was originally reviewed by Geoffrey Kibby in FM18(2). I am surprised to find how often I consult it. Do they have a picture of what I think I’ve found? And does their nice photo look anything like my material? Do they agree it’s rare? etc. etc. A comparison can be made of the corticioid part of this book with the vastly heavier Bernicchia & Gorjon (2012), though anyone seriously wanting to identify corticioids should get both. Each includes a few genera the other doesn’t consider to be corticioid, but this hardly affects the following rough comparison. As far as
A9#D "! #=" #CJ"H #2"J#2 H"J#CI!! # 7;#@37
doi:10.1016/j.fldmyc.2019.01.012
0'
D" ##FE some species you can’t even be sure under oil and SEM is needed, but the writers of keys for ordinary mortals have sense enough to key these as appearing smooth. They are usually less inclined to provide a safety net for readers who miss ornamentation not clearly visible at x400.
significantly different DNA. The transition didn’t happen overnight, more likely over centuries at least, during which it would have been a matter of taxonomic opinion whether they were one species or two. Ecologists analysing soil samples using highthroughput DNA meet this challenge head-on. Instead of talking species they talk only of OTUs (Operational Taxonomic Units) and note that the numbers of these they record differ vastly according to the percentage of base-pairs required to be different in the ITS region before two OTUs are treated as distinct. In many agaricoid genera currently accepted species tend to exhibit differences of over 3% in their ITS base-pairs. Conversely smaller differences tend not to show up as taxa demanding treatment as separate species. But it isn’t as simple as that. Indignant taxonomists, finding their species synonymised on the grounds of close ITS similarity have been known to retaliate and cite other less fashionable DNA regions in support of their case! Lets throw some speculative numbers into this discussion. Suppose the average fungal species, however defined, has a million year life on earth before going extinct. Suppose also there are 20,000 British fungal species. Then in any century on average two will go extinct, and in a steady-state world (one that hasn’t heard of anthropogenic mass extinctions) two will evolve to species level to replace them. So these two at least will tend to present as ambiguously one species or two. I have met field naturalists who are put off fungal identification from a perception that fungal species are still all one big muddle. But plants have similar problems even if on a smaller scale. Ask a botanist how many Mediterranean orchids should be recognised in the genus Ophrys!
# # G"# " "! # "# # "! # "# &$% ' # # " # " "#I ## <#"% 8 #G ## # # ### " #H " "#<# # "G !#I ## #" # HH ! "# #G # # # # " #H "#"# #J ! # # G ?# "!H "# "# # "! # I!8 # " "! ## "! #
Some remarks on species concepts It is acknowledged that, as discussed above, there is a continuum between smooth and ornamented spores (and indeed between thin- and thickwalled spores which often leave me less certain than the writers of keys appear to be). On similar grounds there cannot always be criteria to decide whether two closely related taxa belong to one species or two. Again there is a continuum involved, that of time, from the past when there was only their common ancestor to some later date by which time they have evolved into two undeniably distinct species, intersterile with
Some thoughts on keys I am thinking here of the usual binary keys. Suppose you have eight species to key, each keying out in one place (thus seven couplets). It would be nice, but seldom practical, to find a first couplet that divides them into two groups of four and further couplets to split each of these into two pairs. In this way the user of the key will always reach their answer after making just three decisions. Too many keys approximate to the other extreme where the first two couplets can read:
0(
D" ##FE 1. Is it like this? . . . Species A 1* Not so . . . . . . . . . . . . . . . . 2 2. Or like this? . . . . Species B 2* Not so . . . . . . . . . . . . . . . . 3
about and the more difficult ones (spore ornamentation?) only where unavoidable. • Don’t insist on keying each species out at only one place. • Don’t pick out all the distinctive rarities first just because they are easy to key. They only hang up the reader who has to get past them. • So try and lead the user to the commoner species in as few and as easy steps as possible. • In any key that involves microscopy at all it is a good plan to split up awkward groups into ones with spores above or below a certain size. Spore size is usually easily measured. Borderline species must then be keyed both ways. The key to Psathyrella in Funga Nordica is a good example of this technique, reducing a large genus to fairly manageable chunks.
And so it goes till the commonest and least distinctive species is reached in the final couplet after the reader has had six opportunities to go wrong at each earlier choice. This is hardly a key. There are in fact a great many ways of keying eight species, intermediate between these two extremes. Maths unfriendly readers can skip the next paragraph, inserted for my own amusement, where I discuss just how many. There are obviously just three possible ways of keying three species depending on which of the three is singled out in Couplet 1. What about four species? Any one of the four could be keyed out first followed by any of the remaining three second, leaving the other two for the final couplet. That is already 12 possible keys. Then there are the three ways in which couplet 1 could be used to split the four species into two pairs. So 15 in all. Exercise for the reader: ‘Find an iterative proof that the number of possible keys to n species is the product of the first n-1 odd numbers. So with as few as five species there are already 1x3x5x7 = 105 possible keys. For a reasonable sized key to 15 species multiplying up in this way you reach a 15 digit number! Use of Stirling’s formula for approximating factorials shows that thereafter the number of decimal digits in the answer rises faster than the number of species.
Finally a couple of quotes More and more of the fungi I find now seem beyond my ability to identify. There are all those agaric genera where I have lost confidence in any verdict I reach that's out of the ordinary. I find an unfamiliar Entoloma and I know it's going to cause trouble. Identification attempts get postponed. Eventually I discard it unexamined. When others happily name such things I smugly recall a favourite quote I have seen attributed to Darwin "Ignorance more frequently breeds confidence than knowledge". Not altogether fair of course - some few people do know what they are doing! Another quote that appeals to me appears, unattributed, at the front of Para Sanchez' learned two-volume treatise on Agaricus (Fungi Europaei, Vols 1 + la). He or somebody has declared "Experts do not exist, we are all beginners with greater or lesser knowledge." This one nicely sums up for me the current state of fungal identification.
And thoughts on key construction These stem from my long-held belief that many a published key could easily have been made much more user-friendly with only a little more thought. The aim of the writer of any key should be to maximise the chances of its user arriving at the right species (or, equally important, correctly deciding that their species isn’t covered). To that end some do’s and dont’s: • Don’t go all purist and limit the characters used purely to morphology. • So do mention hosts or habitats or fruiting times or even rarity if any of these help to narrow the choice. • Don’t go overboard trying to make the key match the known phylogeny. • Do use first the easiest characters to be sure
References Hugill, P. & Lucas, A. (2017). The Resupinates of Hampshire. Pixart Printing. Bernicchia, A. & Górjon, S.P. (2010). Corticiaceae s.l. (FE12). Editioni Candusso. Örstadius, L. & Knudsen, H. (2012). Psathyrella. In Funga Nordica. Nordsvamp.
0&