Rustroemia on ivy leaf - Forum ASCOFrance

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Rustroemia on ivy leaf

Charles Aron, 14-02-2020 18:19

Hello everyone. My first contribution to the forum!

Below is a description of a cup fungus looking like a Rutstroemia which I found on a dead ivy leaf but I'm not aware of any of this genus which occur on this substrate.

Regards,

Charles.

Rutsroemia on ivy leaf, Refail Fields, Pentraeth, N. Wales, 11/2/19

Asci: 80x7, 87x8, 90x8, 87x8, 89x8, 87x8.5, 78x7, 90x8,

Spores: 12.5x4, 2x3.5, 12x3.7, 12x4, 13x4.8, 12x3.5, 12.4x3.7, 12x3.9, 12x4.,

Paraohyses tips: 4, 3.3, 3.5, 4,

Excipulum textura globosa-cells thick walled. C 10 across.

FB 3 x 2mm. Cup-shaped. Hymenium bright yellow-brown. Excipulum paler, minutely furfuraceous. Stipe short-c0.5mm.

Raúl Tena Lahoz, 14-02-2020 18:27

Re : Rustroemia on ivy leaf

Hi Charles, welcome to Ascofrance!
It is a Moellerodiscus, from the M. lentus complex. We found it also on ivy leaves in France and Spain. Asci seem to arise from croziers, do they?
Cheers,
Raúl

Hans-Otto Baral, 14-02-2020 18:30

Re : Rustroemia on ivy leaf

Hi Charles

welcome to the forum!

Your fungus seems to be a Moellerodiscus, related to M. lentus. A difficult genus, not easy to give advice. It seems the asci arise from croziers, perhaps you can show this by a closeup on the ascus base? Did you test the ascus apex with iodine (Lugol)?

Zotto

Charles Aron, 14-02-2020 18:39

Re : Rustroemia on ivy leaf

Many thanks for this. I'm not familiar with Moellerodiscus. So it would be fair to call it Moellerodiscus lentus agg.? Will have a look at the asci in iodine.

Charles.

Charles Aron, 20-02-2020 19:27

Re : Rustroemia on ivy leaf

Hi raul& Zotto,

I've had a look at the dried material and croziers are clearly visible. The ascus pore blues in Melzer's after treatment with KOH and the subhymenium turns reddish then brownish in Baral's.

Marginal hairs are quite distinctive and up to bout 50 long.

Very few British records under M. lentus. I was wondering if it has a somewhat southern distribution in Europe?

Regards,

Charles.