However, on searching the forun for Nectria, there ar so many other mediterranean species sthat I came into doubt about my ID. Here is the data

Ascocarp morphology: Clustered ostiolate perithecia
Acocarp colour: Bright red, then blackening when old; purple-blue in KOH, orange-yellow in lactic acid

Ascocarp diameter: 0.16 – 0.32 mm (mean: 0.23 mm)
Ascocarp texture: Rough, Granulated or minutely tuberculate
Ascocarp shape: Spherical then pyriform, opening at the apex by a tiny narrow ostiole sometimes widening to a cupulate shape
Ascocarps sit on a common perithecial stroma, up to 1mm high

Paraphyses not numerous, filamentous, very thin and hyaline, inconspicuous and do not take the stain very well

Ascospore release through an apical orifice without an operculum
Asci: cylindrical to subclavate, slender, slightly bent ot curved, tapering gently towards the base.
No. of Spores 8
Tunic (Wall) Uni-tunicate, hyaline and do not stain well
Ascum length (range) 70 - 100 µm
Ascum length (mean) 84 µm
Ascum width (range) 6.8 - 7.5 µm
Ascum width (mean) 7.1 µm
Ascum L:W ratio 11.8
Iodine reaction (J +/J -) J-ve (but I'm not sure there is a blackish shadoe at the tip with IKI)
Orifice or ascum rim Rim slightly revolute, oriffice narrow, canal-like, surrounded by a thich asus wall.

Spore length: (range) 11.46 - 16 µm
Spore length: (mean) 13.7 µm
Spore width: (range) 4.76 - 7.44 µm
Spore width: (mean) 6.3 µm
Spore Q factor (range): 1.84 - 2.85 µm
Spore Q factor (mean): 2.2
Spore shape: Fusiform to navicular with a constriction at the central septum
Spore septa 1
Spore surface: Smooth or finely rugose when observed at high resolution with LACB
Oil bodies: Two, one at each side of the septum, often seen as a small amorphous body of many aggregates coalescing together until finally forming a distinct globular oil body.
Remarks Spore quite variable in size.

Christian Lechat, 27-02-2017 15:21

Re : Nectria cinnabarina s.l. (or something else)

Hi Stephen,
your fungus is not the genus Nectria but it could be an old specimen of Cosmospora s. l.
Regards,
Christian

Stephen Martin, 27-02-2017 21:27

Re : Nectria cinnabarina s.l. (or something else)

Ok I'm a bit disappointed but  can you please tell me what are the main 1 or two characters which led you to Cosmospora not Nectria (I.m trying to culture on Agar, hope no contamination)

Thanks

Christian Lechat, 28-02-2017 05:10

Re : Nectria cinnabarina s.l. (or something else)

Species of the genus Nectria have globoe and verrucose ascomata, which are seated on a pseudoparenchymatous stroma.
Your fungus as pyriform ascomata and seems fungicolous on your images.

Christian

Stephen Martin, 28-02-2017 08:49

Re : Nectria cinnabarina s.l. (or something else)

Good morning Christian and thank you.  I agree that the perithecia are pyriform and I missed the importance that nectria are globose. I have searched for literature and online sources and I found An overview of the taxonomy, phylogeny, and typification of nectriaceous fungi in Cosmospora, Acremonium, Fusarium, Stilbella, and Volutella by Grafenhan et al. where Cosmospora is described as:


Stroma inconspicous or absent [Not sure]. Perithecia scattered to gregarious[YES], pyriform with an acute or apical papilla[YES], collapsing cupulate or pinched when dry[YES], orange red or bright red [YES], turning dark red in KOH+[YES, but purple-violet], smooth walled [Maybe], usually 150–450 ?m high [YES]. Asci cylindrical to narrowly clavate[YES], with an apical ring [I think I've seen this sometimes, not sure], 8 uniseriate or partly biseriate ascospores [YES]. Ascospores initially hyaline but becoming yellow brown to reddish brown, 1-septate [YES], becoming tuberculate when mature [I think so].

Habitat: On fruiting bodies and stromata of other fungi, e.g.Fomitopsis, Hypoxylon, Inonotus, Stereum, often isolated from soil. [I'm not convinced]

I am not convinced that the perithecia are fungicolous and the black stroma-like bedding seems to be part of the nectriaceae species. Young individual perithecia seems to be growing directly from the stem, so I think we have a lignicolous species rather fungicolous.  How can we confirm this???

Also what literature do you suggest on this topic?

Stephen Martin, 28-02-2017 08:56

Re : Nectria cinnabarina s.l. (or something else)

Here are some more photos of the ascomata...  When young, it seems there is no stroma or then very thin->negligible  (nb fruting bodies are 0.2mm high), but when mature, then colonies are sitting on a black stroma-like mass ?!?   Secondly, for me they look  to be growing directly from the surface of the wood, but then, what is that white layer???   

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Christian Lechat, 28-02-2017 09:18

Re : Nectria cinnabarina s.l. (or something else)

you should make a vertical section through ascomata and stroma deeply in the wood

Stephen Martin, 28-02-2017 09:52

Re : Nectria cinnabarina s.l. (or something else)

No easy to slice smething which is 0.2-0.3mm but I do my best from my eyes and hands. Do you suggest pretreatment eg KOH ?

Stephen Martin, 03-03-2017 21:13

Re : Nectria cinnabarina s.l. (or something else)

I had time to hand section some sections. In my opinion, the fungi are not fungicolous and they started directly on the wood beneath the bark, then they form a blackish stroma which turns violet in KOH and more perihecia are developped gradually above with old ones becoming impregnated at the bottom.  Maybe I am wrong biut that is my interpretation. 

Hope this give some more clues, and I would really appreciate your expert help.

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Christian Lechat, 04-03-2017 04:22

Re : Nectria cinnabarina s.l. (or something else)

I confirm Cosmospora s. l.
Cheers,
Christian

Stephen Martin, 04-03-2017 06:37

Re : Nectria cinnabarina s.l. (or something else)

Thank you. I see if I can manage to grow the anamorph on potato dextrose agar. I am now understanding the genus concepts better. I have one question which is difficult to deduce. Is my specimen fungicolous or corticolous ? Young or isolated ascocarps seems to be growing on the cortex, while mature aggregates are enbedded in a black mass which I can't really convince myself that it is a Pyrenomycete. Can you help on this difficulty as it is an important decission for keying out.

Christian Lechat, 04-03-2017 10:13

Re : Nectria cinnabarina s.l. (or something else)

it could be on a Deuteromycetes,
Chirstian

Stephen Martin, 29-05-2017 13:30

Re : Nectria cinnabarina s.l. (or something else)

I've reposted this fungus with new information.
I managed to grow colonies from the teleomorph producing white colonies

Follow here:


http://www.ascofrance.com/forum?page=1&id=49058

Christian Lechat, 29-05-2017 16:05

Re : Nectria cinnabarina s.l. (or something else)

Hi Stephen,
I think your fungus could be "Cosmospora' flavoviridis, which is not Cosmospora s. str.

Regards,
Christian

Stephen Martin, 29-05-2017 20:29

Re : Nectria cinnabarina s.l. (or something else)

Dear Christian, thank you for your opinion. I have considered also this taxon, but according the key by Rossman and Samuels all 3 or 4 considered taxa have something not matching as follows:

C. meliospicola: Distribution central Africa and North Africa - not european (but Malta is close to Africa!); spore size - OK; Spores smooth to slighlly spinulose - OK; On wood possibly fungicolous (OK-ish); anamorph Acremonium-like - I don't know

C. stilbosporae: Distribution Europe - OK; growing on Valsa sorbi - NO; ascospores (13- )13.5- 16.5{-18.5) x (5.5- )6-7(- 7.5) - a bit too large; anamorph Fusarium - I don't know.

C. flavoviridis (Sphaerostilbe flavoviridis): Anamorph colony greenish - mine where white, but yellowish on SDA (see image); Distribution North temperate (North Europe and UK) - maybe too north for Malta ? ; On stromatic ascomycetes on wood - YES. 

(C. dingleyae: offers a good match but from New Zealand!) 
 
Christian, may I ask why you would exclude C. meliospicola and 2) is my anamorph an Acromonium or Fusarium or Acromenoid-like Fusarium hmm....


Further info: http://www.mycodb.fr/fiche.php?genre=Cosmospora&espece=flavoviridis

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Stephen Martin, 30-05-2017 05:34

Re : Nectria cinnabarina s.l. (or something else)

I have read some more information on C. flavoviridis and it fits best for my specimen as you have kindly suggested. I also found that this species prefers dead branches (same as for my specimen) and occurs in the South of Europe, so the distribution is OK. 

Many thanks for you help. If you need any of my photos high-res for any use, just let me know. As I see this is the first time this Cosmospora is reported on AscoFrance. 

Great!

Related info:
https://www.dgfm-ev.de/publikationen/artikelsuche/ansaetze-zur-erfassung-der-taxonomischen-struktur-der-ascomycetengattung-cosmospora-und-ihrer-nebenfruchtformen/download