• Stromatised substrate and macro like genus Rutstroemia.
• Micro seems good for Rutstroemia too.
• Quercus petioles, macro, and spores suggest R. sydowiana.

Habitat: Stromatised petiole of Quercus robur, well-decayed leaf (but luckily the apex was intact), at the top of damp leaf litter, next to a pond, mixed deciduous woodland, Low Weald, England, early September, after lots of rain.

Apothecia: Appears to have been two, light brownish to blackish with yellowish disc, superficial, diameter ~3 mm and height similar, tooth-like groups of marginal hairs with exudate, concolourous with disc, disc appears shallow and plano-concave in maturity, with gelatinous appearance, receptacle with uneven and felty texture, darker network of hyphae visible, stipitate, blackened in lower-part, stromatised petiole with blackened mummified appearance.

Associates: Further up the petiole/mid-rib, several tiny, whitish, stipitate apothecia, size and colouring suggests a different species.

Asci: ~120-130 x 10-12 um, cylindrical-clavate, 8-spored, biseriate when turgid, croziers, apical ring strongly bb, seems like typical Rutstroemia form, apex rounded-truncate, more truncate when flaccid, apical thickening noticeable when immature or flaccid.

Spores: Reniform, apex hemispherical, base +/- acute, noticeably to strongly curved in profile view, inside the asci apparently filled with many tiny VBs but most coalescing in free spores to form ~3 large to medium VBs, apparently aseptate and uninuclear.

Measurements in water or IKI: (12.5) 13-15 × 5-6 µm, Q = (2.2) 2.5 - 2.76 (2.8), n = 10, mean = 14.1 × 5.4 µm, Q mean = 2.6.

Paraphyses: Long, cylindrical, irregularly inflated toward apex (~2.5-5 um), occasionally branched or bent at apex, multi-septate, apical cells filled with large yellowish VBs, possibly taller than the asci, some noticeable amyloid contents.

Marginal cells/hairs: Multiseptate, ~2-4 cells protruding, irregularly cylindrical, apparently gelatinised, with orangish brown exudate, around margin and on flanks, associated with the darker hyphae on the surface of the excipulum.

Medullary: Textura intricata (typica), appears to be separated from ectal ex. by several rows of horizontal hyphae, looks darker towards subhymenium.

Ectal ex: Hyaline, narrow hyphae on the surface, textura porrecta, patches of exudate, underneath large cells, textura prismatica, cells size seems to distinguish from horizontal hyphae.