Beiheft 137 (2010)
The Xerula / Oudemansiella Complex (Agaricales)
Key to the agaricoid genera of the complex
1 Basidiomata as in Tricholomopsis or Lentinula, fruiting directly on exposed wood, often with ephemeral or persistent partial veil; pileipellis an ixotrichoderm,ixohymenoderm or polycystoderm with mostly inflated and branched filamentous hyphae or clavate terminal elements but sometimes becoming cutis-like by maturity 2
1*Basidiomata as in Collybia or Clitocybe, probably arising from buried wood,without annulus (except H. velata), usually with distinct pseudorhiza; pileipellis a continuous and regular hymeniderm, dry or viscid, with or without thick-or thin-walled pileosetae. . . . . . .8
2 Basidiomata without persistent annulus (annulus may remain as fugacious remnants or a subtle ridge on stipe); pileus surface sometimes with integral patches resembling velar tissue 3
2* Basidiomata with persistent annulus (absent in Armillaria tabescens) 7
3 Basidiomata small (pileus rarely exceeding 30 mm broad); pileus and lamellae various 4
3* Basidiomata larger;pileus surface smooth, moist to viscid; lamellae white to cream-coloured, thin 5
4 Basidiomata erect, not as Tricholomopsis; pileus surface granulose-floccose, bright yellow-gold to yellow-orange; lamellae thick, white, subdistant: pantropical ................ Cyptotrama*
4* Basidiomata fruiting laterally, like Tricholomopsis: pileus surface brown, smooth; lamellae thin, white; neotropics ....... Pseudohiatula*
5 Spores ornamented, warty; pileus surface bright pink to coral-colored,wrinkled; lamellae thin, pallid pink; basidiomata fruiting laterally, like Tricholomopsis; temperate zone ............... Rhodotus*
5* Spores smooth; pileus not pink or coral-colored 6
6 Pantropical, extending into South Temperate Zone; pileipellis an ixohymenoderm , ixotrichoderm or polycystoderm; pleuro- and cheilocystidia prominent; spores > 14 µm diam, subglobose, thick-walled. . . . . . . . Oudemansiella
6Temperate; pileipellis an ixohymenoderm of branched termini or inflated cells with multiple slender out growths; spores of moderate size, usually ellipsoid, thin-walled; basidiomata medium-sized to large ......... Flammulina
7 Pileus viscid to glutinous; pileipellis an ixohymenoderm; pleurocystidia prominent;spores large, thick-walled, subglobose; temperate...... Mucidula
7* Pileus dry to moist,with minute pyramidal scales over the disc; pileipellis a cutis of repent hyphae; pleurocystidia few and inconspicuous; spores usually thin-walled, rarely subglobose; cosmopolitan .......... Armillaria*
8 Spores ornamented with awl-shaped spines; pileipellis viscid; neotropics; basidiomata often diminutive Dactylosporina
8* Spores smooth; pileipellis dry; cosmopolitan; basidiomata collybioid, moderate to large....... 9
9 Fruiting on dead strobili of conifers or Magnolia ............. Strobilurus*
9* Basidiomatal origin obscure, probably on buried wood but not strobili of conifers or Magnolia; pseudorhizal......... 10
10 Basidiomata marasmioid, gracile, radicating; pileus dry; stipe black, cartilaginous............... Rhizomarasmius*
10* Basidiomata stouter, collybioid; stipe not black ............ 11
11 Pileus surface dry: pileipellis composed of inflated pileocystidia and thin-to thick-walled setoid elements; North Temperate ..................... 12
11* Pileus surface moist to glutinous; pileipellis composed of inflated pileocystidia,with or without thin-walled pileal hairs.............13
12 Pileosetae thick-walled (wall-7µm thick), stiff, brittle,blond to rufous brown.......... Xerula
12* Pileosetae thin-walled (wall-2 µm thick), flexuous, proximally inflated, hyaline to blond ........... Paraxerula
13 Eastern and Western Australia; pileus citrine- to olive-green; spores ellipsoid, thick-walled ........ Protoxerula
13* Cosmopolitan; pileus some shade of brown or olive-brown (sometimes pallid to almost white); spores subglobose, ellipsoid to limoniform, thin-walled................. Hymenopellis
- Genus not covered in this work