Summary:
Features include 1) a small, blackish cup densely clothed with coiled hairs that give the exterior a tomentose appearance, 2) absent (or sometimes short) stem, 3) growth on wood or ground under conifers, and 4) microscopic characters including smooth, round spores and forked paraphyses that are not thickened or coiled at the tips. This is not to be confused with Donadinia nigrella (= Plectania nannfeldtii) which is based on a different type collection.

Microscopic:
spores 10-12(13) microns in diameter, round, smooth, colorless, sometimes with 1 large droplet; asci 8-spored, 250-300 x 11-13 microns, negative reaction to iodine; paraphyses filiform [thread-like], "multiply septate, tips straight and not clavate, but forked with lateral outgrowths"; hairs cylindric, dark brown, "smooth, with few septa, thin-walled, with few branches, woven together and felt-like", (Breitenbach), spores reaching 12-14 microns in diameter, round, smooth, usually containing one large oil droplet and several smaller ones; asci reaching a length of 300-325 microns and a width of 15 microns, cylindric or subcylindric with long stem-like base; paraphyses enlarged at tips and filled with brown coloring matter, reaching 4 microns wide; hairs reaching 4-6 microns and of nearly uniform width throughout their length, very long but usually coiled and twisted, pale brown, sparingly septate, (Seaver), spores 10-12 microns in diameter, round, smooth, filled with numerous small oil droplets, uniseriate; asci up to 350 x 16 microns; paraphyses slender, forked, not widened at tip, brown, (Dennis)

Notes:
Pseudoplectania nigrella is found at least in BC, WA, OR, ID, CA, CO, UT, and WY, (Larsen), NJ to MB, WI, AL, Jamaica, Europe, and Australia, (Seaver), Switzerland (Breitenbach), United Kingdom (Dennis), and Denmark, Finland, Norway, and Sweden, (Hansen).

Synonyms and Alternate Names:
Polyporus obliquus Pers.: Fr.
Poria obliqua (Pers.: Fr.) Quel.