Ascocarps in vertical section initially subepidermal, host epidermal cells becoming filled with dark brown, thick-walled fungal cells as ascocarp matures. In mature ascocarps upper wall -5 µm wide, not varying in width across ascocarp, on inside of upper wall near ascocarp opening is a 15 µm wide layer of hyaline, cylindric, 2 µm diam. cells. Lower wall 15-25 µm wide.

Paraphyses 1.5-2 µm diam., swelling gradually to 2.5-5 µm at apex, embedded in gel, extending 10-20 µm beyond asci. Asci (135-)155-185(-220) x 5-7.5 µm, cylindric, tapering slightly to broadly truncate apex, wall at apex slightly thickened, sometimes with small central pore, 8-spored. Ascospores 75-130 x 1-1.5 µm, tapering slightly to both ends, often bending at right angles when released, 0-1 septate, indistinct gelatinous sheath.

Pycnidial-like structures in vertical section 30 µm high, upper wall lacking, lower wall 5-10 µm wide, of 1-3 layers of 4-8 µm diam., brown, thick-walled cells. No conidia or conidiogenous cells seen.

ETYMOLOGY: nigrofactum = blackened; refers to blackening of host tissue around ascocarp.

NOTES: L. nigrofactum is similar to L. tindalii and L. brunneolum, two other Dracophyllum-inhabiting species. Most collections of L. nigrofactum differ macroscopically from these other two species in having linear rather than elliptic ascocarps and in having ascocarps associated with black staining of the surrounding host tissue. See also notes under L. brunneolum.