• Macro and habitat seems like Hymenoscyphus s.l.
• Supported by paraphyses, spores and ascus rings.
• The spores, excipulum, and substrate make me think H. s.s.
• Possibly H. caudatus, based on spores, asci, and macro.

Habitat: On petioles and veins of dead leaves of Salix cf. caprea, possibly on a Betula cf. pendula leaf too (no micro), leaves well decayed, on the top of leaf litter, at the edge of a pond, mixed deciduous woodland, Low Weald, England, mid-September, after rain.

Apothecia: Whitish-yellowish, very small, diameter < 1 mm, short stipitate, receptacle whitish, disc opaquer and more yellowish, eventually plano-convex, margin uneven, relatively indistinct.

Asci: Mature and turgid ~110-125 x 8.5-10 um, cylindrical-clavate, 8-spored, biseriate when turgid, simple septa, rings bb, Hymenoscyphus-type, apex acute-truncate, thickening noticeable when flaccid, collar-like opening.

Spores: Scutuloid, quite variable, constricted in the middle, poles rounded, many smallish LBs in each half, most appearing to coalesce into 1-3 of medium size (in each half), uninucleate and aseptate.

Free spores in water: (13.8) 15.4 - 18.7 (19.3) × (4.2) 4.4 - 5.3 µm, Q = (2.7) 3.1 - 3.7 (4.4), n = 30, mean = 16.6 × 4.8 µm , Q mean = 3.5.

Paraphyses: Narrow cylindrical, ~2-4 um wide, multi-septate, rarely branching towards the apex, Hymenoscyphus-type VBs (apex with many medium-size, globose, dextrinoid VBs), pale yellow/chlorinaceous.

Medullary ex: Possibly textura porrecta (not tangled enough for intricata?), hyaline.

Ectal ex: Textura prismatica, hyaline.