Nigrohydnum is a fungal genus in the order Polyporales.
It contain a single species, Nigrohydnum nigrum, a rare toothed polypore known from only a few collections in Brazil.
The spines on the cap underside are up to 3 mm long, and are densely packed, numbering about 1–3 per millimetre.
The spores of Nigrohydnum nigrum are cylindrical, thin-walled, hyaline, and measure 4.5–2 μm.
[2] After an old voucher specimen was discovered in a herbarium and identified to be N. nigrum, the geographic distribution was extended to the Atlantic rainforest of Porto Alegre, Rio Grande do Sul state, in Southern Brazil.