Inocybaceae: Inocybe

Inocybe brunneodisca Matheny, Bougher & Gates, nom. prov.

PILEUS 15-32 mm, conical to broadly convex to plano-convex or plane, umbo lacking or at most low and obtuse, margin decurved to straight, upturned in age; surface dry or occasionally moist, dull, velipellis absent, at times with adhering clay particles; center smooth and unbroken, radially fibrillose towards the margin, not rimose but on occasion fibrils spreading towards the margin, which can be torn at times; center almost Sepia or Saccardo’s Umber to dark brown (7.5YR 4/2 – 4/3 – 3/2) when young, later very dark grayish brown (10YR 3/2) to dark brown or dark grayish brown (10YR 3/3-4/2), fibrils spreading towards the margin giving way to (light) yellowish brown (10YR 6/4 – 5/4) or pale brown to very pale brown (10YR 6/3 – 7/3) ground color, uniformly brown or Tawny Olive to Saccardos Umber when young; context watery pale brown to pale grayish brown, several millimeters thick under the disc, odor none, color unchanging where cut. LAMELLAE adnexed, moderately close to very close, ca. 40-60 L, with several tiers of lamellulae, light gray (10YR 7/1 – 7/2), very pale brown (10YR 7/3) to brown (10YR 5/3) or clay colored in age, edges pallid but not distinctly fimbriate, ventricose, 4-5 mm wide. STIPE 25-50 × 3-5 mm at apex, terete, base swollen or somewhat bulbous to bulbous, in some cases distinctly marginate (PBM3364 and PBM3402, base -9 mm wide), base 6-8 mm wide, cortina absent, white pruinose entire length with a satiny fibrillose streaked appearance, white or pallid throughout or with a pale yellow (2.5YR 8/4) ground color; context solid, pink tinges none, pallid, nearly white above the bulb.

SPORES (8.0-) 8.5-9.8-10.5 (-11.5) ± 0.65 × 6.5-7.2-7.5 (-8.0) ± 0.46 mm, gibbous with mostly 8-12 small to moderate sized nodules, not prominently nodulose, yellowish brown (n=42/3). BASIDIA 31-32 × 10.5-11.5 mm, 4-sterigmate, sphaeropedunculate, hyaline. PLEUROCYSTIDIA 62-86 × 14-20 mm, fusiform or cylindric, occasionally more ventricose, rarely saccate, necks not delineated, merely tapered at both ends; apices obtuse and crystalliferous, below without a distinct pedicel; thick-walled, walls 2.0-3.0 (-5.0) mm thick, hyaline; moderately frequent. CHEILOCYSTIDIA similar to pleurocystidia but shorter and more variable in shape including cells lageniform in outline, at times not as thick-walled, mixed with numerous hyaline paracystidia. CAULOCYSTIDIA similar to cheilocystidia, mixed with cauloparacystidia and descending the entire length of the stipe. PILEIPELLIS a cutis of cylindric to inflated hyphae mostly 7-24 mm wide, these incrusted with pigments visible at 400X, yellowish brown to cinnamon brown in mass. CLAMPS present.

HABITAT: on soil in wet sclerophyll under Eucalyptus regnans or E. obliqua mixed with Acacia and Pomaderris. Known to date only from Tasmania but likely also occurring in other regions of southeast Australia. May-June.

SPECIMENS EXAMINED: AUSTRALIA: TASMANIA. Scattered singly on soil in wet sclerophyll under Eucalyptus regnans, Acacia, and Pomaderris, Mt. Field National Park, 8-Jun-2009, leg. P.B. Matheny, G. Gates, & D. Ratkowsky (PBM3214, TENN065797); scattered singly on soil in wet sclerophyll under Eucalyptus regnans, Acacia, and Pomaderris, Mt. Field National Park, 8-Jun-2009, leg. G. Gates, D. Ratkowsky, & P.B. Matheny (PBM3220, TENN065798, isotype), HO (holotype); scattered singly on soil under Acacia, Eucalyptus, Pomaderris, and Zieria arborescens, Halls Falls Track, outside Pyengana, 21-May-2010, leg. G. Gates, D. Ratkowsky, & P.B. Matheny (PBM3364, TENN065788); same locality and date above, under Eucalyptus obliqua and Acacia, leg. P.B. Matheny & F. Karstedt (PBM3365, TENN065799); scattered singly on soil under Eucalyptus obliqua, Acacia, and Pomaderris, Halls Falls Track, near Pyengana, 23-May-2010, leg. P.B. Matheny, F. Karstedt, & M. Noordeloos (PBM3402, TENN065800).

COMMENTS: Inocybe brunneodisca is best recognized the bicolorous pileus in age with a dark brown or umbrinous disc often with streaky fibrillose appearance towards the pale margin, the entirely white or generally pallid pruinose stipe with a slightly bulbous base and pink tinges absent, the gibbous spores with typically 8-12 small nodules, and the thick-walled, typically fusiform pleurocystidia. Two of the five collections here displayed a distinct marginate bulb, but this trait is somewhat variable given the high DNA sequence similarity among the collections and the lack of a distinct bulb in others. In the field, I. brunneodisca may have adhering soil particles on the pileus surface. The species so far has only been recorded from wet sclerophyll communities including Eucalyptus regnans, E. obliqua, Acacia, and Pomaderris. The combination of features here is not evident in any previously described Australian and New Zealand species.