Habitat: On a short twig, looks like Quercus, apparently on the ground (not observed in situ), damp and muddy area, by a large pond, mixed deciduous woodland, Low Weald, England, late-September, after rain.

Apothecia: Medium-size Rutstroemia-like, four counted on the twig, loosely grouped, varying stages of maturity, diameter < ~6.5 mm, stipe < ~4 mm (relatively short), orangish-brown, cupulate, receptacle with uneven appearance, covered by a network of darker hyphae, margin distinct, round, bumpy or uneven appearance due to glassy exudate (around marginal hairs), remaining slightly raised above the disc, stipe mostly blackened from the base, covered with short whitish hairs (long hyaline hyphae) under low magnification, disc concave but becoming more plane, shallow, opaque, dull and slightly darker appearance, but lighter and grainy appearance with darker flecks (paraphyses) under low magnification, some localised blackening around the base.

Asci: Narrowly cylindrical-clavate, croziers, rings mostly bb but occasionally more dirty rb, form seems typical Rutstroemia, apex rounded-conical when turgid and more acute-truncate when flaccid, more hemispherical when immature, thickening substantial when immature or flacid, obtusely biseriate when turgid, not inverting post discharge, after some time many asci discharging in water mount.

Spores: Ellipsoid, homopolar, poles rounded-acute, length varies considerably, usually two large and conspicuous LBs and a smaller one towards each pole (smaller more extreme), and many much smaller ones, free spores occasionally with 1-3 (5?) septa, each cell with a predominant LB (larger towards the centre), some budding from the poles (not seen in asci), ascoconidia < ~ 4 x 3 um with one relatively large LB, budding spores shorter and wider with less or smaller LBs (some moving to ascoconidia).

Free spores in water (not budding): (15) 15.8 - 18.9 (19.3) × (4.3) 4.8 - 5.8 (6.0) µm, Q = (2.9) 3.0 - 3.7 (3.9), n = 30, mean = 17.6 × 5.4 µm, Q mean = 3.3.

Paraphyses: Cylindrical, width ~ 2.5-3.5 (4) um, multi-septate (some with at least 5), apical cell usually longer (< 3.5x), this with cylindrical VBs, strongly pigmented dirty-yellow, more reddish en masse, apex usually slightly inflated and occasionally irregular, no branching observed close to the apex.

Excipulum etc. looks typical for Rutstroemia.

Hans-Otto Baral, 26-09-2024 11:56

Re : Rutstroemia firma

This is interesting. I never understood if there are two species of R. firma, one with straight and one with curved spores. Similar as in Tatraea I assume that a DNA analysis would reveal a difference. There exist many sequences of R. firma, but even for the two from Guy I have no info about the spores. One was on an attached Quercus branch and the other more hygric on the ground, but they are identical in the ITS.

The spore septa occur only when the spores are overmature, and budding even later.

Could you tell me the exact date, then I can name the pics.

B Shelbourne, 26-09-2024 20:25

Re : Rutstroemia firma

Thank you for explaining about the maturing spores. The collection data for this should be the same as the Ascotremella faginea (22/09/24).

Your idea about the spore shapes is interesting, and some examples in the Quercus folder look quite different to these ones. Boudier's drawing is difficult to categorise on curvature but some of the spores have the more heteropolar shape. Do you know of a type specimen? The older descriptions have no microscopic details and the lectotype details on IF seem strange.

I can mail a sample to Pablo for ITS, but then we need a sequence from the other phenotype to test the hypothesis.

Hans-Otto Baral, 26-09-2024 20:58

Re : Rutstroemia firma

It is perhaps not easy to divide the available docus into two groups, but I think for most of them it would work.

I should ask Guy for his docus, hoping he has some and has access.

One of the CBS sequences (341.62) comes from Berthet 1964 from a French sample. Only 1 spore illustrated, straight/inequilateral, clearly not curved. But he treated 3 finds and did not specify from which the spore came. This sequence is identical to Guy's two and to some others.

It is actually often so, either we have a sequence or a detailed docu, but rarely both from one find. A pity that your detailed studies are not accompanied by sequences.