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Physarum cf pusillum

Posted: Tue Jun 06, 2017 9:07 am
by MaxRum
I need a bit your help on this Physarum with stalked limy sporocarp. The mature sporocarp is grey and its red-mahagony long stipe, absencse of columella and lime nodes in capitulum is suggesting P. pusillum. Spores fits I think

what pushes me away is the fact that the young sporocarps where pinkish-salmon, then steel blue and finally chalky grey-white and that they were growing on soil which had a mixture of organic matter (farm animal/chicke bed?) composed of kind of wood chips not on herbaceous substrate.

Here is two pics of the immature and semi-mature myxocarps. If P. pusillum is usally like this when young, let me know. I can provide more pics and data on request.

Re: Physarum cf pusillum

Posted: Tue Jun 06, 2017 9:16 am
by MaxRum
Here is a nice image of the mature sporocarps, 4 months after collection. Note the blackened plasmodium and the yellowish tinge at the base of the sporocarp. Soil calcareous.

Re: Physarum cf pusillum

Posted: Tue Jun 06, 2017 10:34 am
by MaxRum
Photos of capitulum lime nodes and spores at x1000 are provided here. Sporocysts 0.4-06mm; Spores 9-11um with fine spinulose surface, sometimes aggregated forming dark bands or craters. The spores has a wide border which i don't know what it is !!!

Re: Physarum cf pusillum

Posted: Tue Jun 06, 2017 12:07 pm
by Pitufo
Hi MaxRum

Nice photos - you've captured the capillitium beautifully. I always find that difficult.

Your ID looks likely. However, I don't know for sure if the sporocarps are this colour when young but it wouldn't surprise me.

I think the thick layer you see around the spore is just optical sectioning of the spore wall at high magnification/shallow depth-of-field, but I could be wrong.

Would it be possible to get a sample of this from you if you have any spare and if the substrate is amenable? It looks like it may be a bit crumbly on drying.

Kind regards,

John

Re: Physarum cf pusillum

Posted: Tue Jun 06, 2017 12:57 pm
by MaxRum
Hi Pitufo john!

Thank you for your opinion. The spores are like that, even at x400 and mounted in water+lactic acid. Another closely related taxon is Physarum pusillopse but they have larger spores (12um) and sporocarps (0.8-1.2mm), so I have discarded it upon that. The largest sporocarps in this population were 0.8mm but on average, 0.5mm.

Like you I think we have a quite unusual P. ousillum but within the range of the species, main differences being the pink-red immature sporocarps, the ring around the spores and the Y-shaped capillitium lime nodes (maybe this is irrelevant!)

I have a soil bolus that i can send iy but I am concerned about breaking and getting damaged during transport. Let me post some more Myxo that I have for ID maybe you get interested in a second sample and i send everything at one go.

Capitullum image: using stereomicroscope I transfer abt 10 sporocarps ( one or two onle with part of stalk) in drop of tap water (ours already with some lime!) and gently break the sporocarp with 3-5 stabs with dissecting needle (not more) and then I swirl around but not over. I get something like that by luck.

Re: Physarum cf pusillum

Posted: Tue Jun 06, 2017 5:33 pm
by Pitufo
I thought the substrate might be a bit flaky and hard to transport. There is some info here on how to box up myxos should you need it viewtopic.php?f=8&t=1463

I might be able to get you a closer look at the spores if you want to put a few sporocarps in a small bag. Are you in the UK?

Kind regards,

John

Re: Physarum cf pusillum

Posted: Wed Jun 07, 2017 6:40 am
by MaxRum
That's cool! I'm from M alta btw and an amateur on Myxos! I wonder if I can buy empty match boxes online as we do not use them that often. I check with my relatives too.

In the meantime I attach another image of the spores which now assumed a blue-berry pie :-)

Re: Physarum cf pusillum

Posted: Wed Jun 07, 2017 11:28 am
by Pitufo
I think what you are seeing in the spores is an artefact of treatment with Lactic Acid Cotton Blue - It may be dehydrating the centre of the spore due to osmosis or some other effect.

Cheers,

John

Re: Physarum cf pusillum

Posted: Wed Jun 07, 2017 1:33 pm
by MaxRum
I think you are right, its like shrinking and collapsing over itself. I will mount some spores in water and congo red soon
TNX

Re: Physarum cf pusillum

Posted: Wed Jun 07, 2017 5:21 pm
by MaxRum
I confirm that the wide border is some sort of artifact caused by the staining or lactic acid. A fresh mount in water did not show this wide border.