Arum maculatum: a full set

[Simon Horsnall]

So I went out today in the hope of finding several of the microfungi associated with Ficaria verna given the excellent information posted by Chris last year and everybody else’s finds. Unfortunately, I managed only Uromyces dactylidis. However, I did manage what I think is a full set for Arum maculatum.

Puccinia sessilis, I didn’t photograph this one.

Ramularia ari, this is the one I am least confident on but it looks very Ramularia like.

Melanustilospora ari, I have checked the black pustules and they do contain spores so I am fairly confident on the determination. I understand this represents a considerable expansion on its known range.

[Simon Horsnall]

Forgot to add: SK4841, Cossall, VC56, 18/iv/2018

[attachment=0]IMG_0329.JPG[/attachment]

[Chris Yeates]

Hi

I won’t comment until I can see the pics – not your fault, I fully appreciate, Simon. Do you have images of the smut spores?

cheers

Chris

[Simon Horsnall]

I shall try again. Unfortunately, I cannot get images of the smut spores. What looks like a very good spore through the eyepiece looks like a blob of gunk through the camera. I really need to improve my micrograph technique.

I collected fresh material today from the same plants so if anybody would care to look at a dried sample, I am happy to send.

[Chris Yeates]

Hi

Not easy to see but the Ramularia looks to be OK – I think I can make out the white tufts of conidia. I think the dark markings on the other hand are simple anthocyanin pigmentation, very often seen on Arum maculatum; a good clue is that thin dark margin to the leaf – again due to anthocyanin pigmentation. Vanky in his monumental book on European smut fungi (1994) talks of lead-coloured pustules; these are not pustules but depressions in the leaf. There appear to be a lot of misdentifications on the web, which doesn’t help matters.

Perhaps the “gunk” is made up of the pigmented cells of the plant, true ustilospores would be quite distinct, obvious, and float around in a water mount.

Sorry but that’s my honest opinion; I’d be happy to look at specimens for you, and next time I come across a spotted Arum leaf – they’re pretty frequent in this part of West Yorkshire – I’ll try and do a mount, just to see what the pigmented plant cells look like.

Here is the relevant image from Vanky (1994):

[attachment=0]Mel-ari.jpg[/attachment]

Regards

Chris

[Simon Horsnall]

Thanks Chris for your opinion.

I was lead to believe that the spotting (very common round here too) was different to the sunken depressions as the spotting tends not to be visible as greyish markings on the underside (this is how I initially screened the leaves).

When I say gunk, they look reminiscent of WW2 sea mines down the eyepiece, I just can’t seem to get the lighting/focus correct to get a decent image through the camera.

Anyway, I am willing to bow to your superior knowledge.

Simon

[markwilson]

I don’t think the one with depressions is fungal. I have sent specimens to Dr Brian Spooner who could not find fungal material present.

See

https://www.ispotnature.org/communities/uk-and-ireland/view/observation/608441/megaspotty-2

In C T Prime’s book on Lords and Ladies these “Repoussé” forms are mentioned. A paper from the Irish Naturalist 1911 by N Colgan says that they are inherited.

I have now found these in 5 locations in W Somerset and one in Essex and a few other examples have turned up on iSpot.

I am still trying to find more out so if anyone knows anything please comment

Thanks

Mark

[markwilson]

Forgot to mention

https://bladmineerders.nl/parasites/fungi/basidiomycota/ustilaginomycotina/ustilaginomycetes/urocystidales/urocystidaceae/melanustilospora/melanustilospora-ari/

Says that not pathological

Mark

[Simon Horsnall]

Thanks Mark, I had forgotten all about this. It is very interesting that the sunken spots seem to be genetic.

Simon

[Fay Newbery]

Simon, when youre collecting Ramularia specimens, don’t forget that if put the sample in a plastic bag or box with some wet tissue for a couple of days, you’ll get more clumps of conidiophores forming and they’ll be easier to confirm.

Have you seen Arthur Chater’s new Ramularia guide? Download from this page: https://www.aber.ac.uk/waxcap/links/index.shtml

Good to see posts on pathogens. Thank you.

[Peter Roberts]

Ray Woods and Arthur Chater got me looking at a lot of Ramularia species last year (we seem to have a very pathogen-rich garden – despite my best efforts!) – but, as far as I understand, there is no true Ramularia species that occurs on Arum. Spermosporina aricola is a suggestion for “Ramularia ari” – but I don’t have the literature to hand.

[Simon Horsnall]

Thank you Fay and Peter. I am using Ellis and Ellis and they list it as Ramularia ari. I know it is lax of me not to follow up every taxonomic review so thank you for pointing this out. I assume it is a nomenclatural change based on a tighter delimitation of the genus Ramularia? If so, I shall annotate my copy.

Simon

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