micros (scale=10 µm)

Acanthostigma minutum ?

Hi Gernot,
this is most likely an Acanthostigma (Tubeufiaceae) because of its small pale-coloured ascomata with a bunch of dark stiff setae around the ostiole, and spore shape. The spore dimensions you give do not fit well the common A. minutum and more resemble those of A. scopulum (56-78 x 2.5-3 µm) in being more narrow and curved. In fact your fungus appears somewhat intermediate between the two species.
Could you check the dimensions again?
Cheers,
Jacques

Questions for Jacques,
In fact it's the length of scopulum's spores and the width of minutum's spores ?
I would like to know if, as Margaret Barr noted, scopula is mostly restricted to coniferous trees ? Do you know recolts on deciduous trees ?
But wait for other measures of ascospores.
Alain

Hi Alain and Jacques,

thank you very much for your answers! A. minutum also grew on that branch but it is really different to me due to it's bigger ascomata and spores. It fits very well to the description of Barr & Réblová and to the fungus which Zotto showed once ( http://www.ascofrance.fr/index.php?r=forum&page=viewtopic&id=7665&highlight=minutum#msg7675 ).

The form of the spores within this collection (the one I showed above) would fit A. scopulum really very well but not the width, as you mentioned, so I will check on this again.

Here I have pictures of A. minutum.

Best wishes,

Gernot

micros (scale=10 µm)

the spores are obviouly too narrow for minutum and too broad for scopulum.
A. minutum has a small ascomata, so when you say those of your fungus are smaller they are indeed very small?
I suggest you check your fungus against Reblova & Barr's description of A. minutum and list all the differences. Maybe a professional will be interested....
Jacques

Acanthostigma ellisii. Key below from my paper in press at Mycologia. It will appear in the May-June 2010 issue.

Andy

KEY TO SPECIES OF ACANTHOSTIGMA2
1.1 Ascospores less than 5 mm wide . . . . . . . . . . . . . . . 2
1.2 Ascospores $5 mm wide . . . . . . . . . . . . . . . . . . . . . 6
2.1 Ascospores up to 4 mm wide. . . . . . . . . . . . . . . . . . 3
2.2 Ascospores 4–5 mm wide . . . . . . . . . . . . . . . . . . . . 5
3.1 Ascospores 22–27 3 3–3.5 mm, 5(–9)-septate. . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. revocatum
3.2 Ascospores more than 30 mm long . . . . . . . . . . . . . 4
4.1 Ascospores (40–)56–78(–95) 3 (2–)2.5–3(–3.5) mm,
10–14-septate. . . . . . . . . . . . . . . . . . . . . A. scopulum
4.2 Ascospores (75–)85–135(–150) 3 2.5–4 mm, 12–16-
septate . . . . . . . . . . . . . . . . . . . . . . . . . . A. filiforme
5.1 Ascospores (29–)38–51 3 4–4.5(–5), (4–)6–8-septate
. . . . . . . . . . . . . . . . . . . . . . . . . . . A. longisporum
5.2 Ascospores (38–)48–64.5 3 4–4.5 mm, 6–12-septate
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. ellisii
6.1 Ascospores not or slightly constricted at the septa . 7
6.2 Ascospores constricted at the septa, 40–50 3 5–
6.5 mm, 7–10-septate . . . . . . . . . . A. septoconstrictum
7.1 Ascospores 30.5–35.5(–42) 3 5–6 mm, (5–)6–7(–8)-
septate . . . . . . . . . . . . . . . . . . . . . . . A. perpusillum
7.2 Ascospores longer, $10-septate . . . . . . . . . . . . . . . 8
8.1 Ascospores 40–55(–63) 3 (5–)6–7(–7.5) mm, 10–14-
septate . . . . . . . . . . . . . . . . . . . . . . . . . A. minutum
8.2 Ascospores 60–90 3 5–7.5 mm, 14–18-septate . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . A. multiseptatum

thanks so much Andy for your expert answer!
Your key is certainly fine but it will be easier to use when it is not encoded!
We'll be patient until the next issues of Mycologia.
Gernot you are lucky for this time, you got a name for your fungus!
Jacques

The decoded version costs extra Euros... ;o)

Sorry about that! I have uploaded the entire article as a PDF. Enjoy...

Andy

thanks Andy,
species of Acantostigma often show up on Ascofrance, so your fine paper will be very useful to us, for a very reasonable price indeed!
Jacques

Hi,

thank you very much, Andy! It's great you uploaded your paper, it's really helpful. So I have A. ellisii and A. minutum on one piece of branch, I guess this is a great coincidence.

@Jacues: Yes, the ascomata of A. ellisii were really very small, quite challenging to take a photo of them.

Best wishes,

Gernot

You are most welcome. I would not be surprised if you had more than one species of Acanthostigma growing on the same piece of wood. They tend to fruit at the same time on similar substrates.

Andy

Thank you for sharing your paper with us!

Best regards,

Martin

I just reappointed an old recolt of Acanthostigma. It also was A. ellisii.
Thanks a lot !
Alain

Great paper for this interesting genus, thanks for sharing!