We found this Lachnum on an old Rubus stem.
Fruitbody:
Very hairy white outside, with a white-cream hymenium, with hairy stipe.

Structure:
Only textura prismatica observed, difficult due to the many long hairs.

Hairs:
Incrusted to the apex, therefore Lachnum.
Cylindrical, no/hardly thickened apex, no crystals.
Flank of hairs measured in water: Me = 148.2 µm
Edge of hairs measured in water: (119.7) 119.71 - 119.8 µm

Asci:
Measured in water: 41.6 - 47.9 × 5 - 5.09 (5.1) µm
Croziers + and IKI +

Paraphyses:
Lanceolate, full of guttules.
Width measured in water: (4.5) 4.6 - 4.7 (4.8) µm
Protruding above asci measured in water: (5.5) 5.52 - 9.17 (9.2) µm

Spores:
Cylindrical, sometimes narrower at one end.
Measured in water: (7) 7.4 - 9.5 (10) × (1.6) 1.7 - 2.1 (2.2) µm, Qe = 4.3

Using Baral's Lachnum key, we arrive at - - +, no crystals, no strong/medium refractive VBs, croziers +.
Subkey 5 -> Lachnum virgineum.
The only thing that doesn't quite fit is that the paraphyses should protrude 15-30 µm, we measure a max. 9 µm, and the width of the paraphyses should be 5-7 µm, we measure a max. 4.8.
Is it a different species after all?

Kind regards, Geert&Margot Vullings