Inocybaceae: Inocybe

Inocybe scissa (E. Horak) Garrido

Bibliotheca Mycol. 120: 177 (1988)

PILEUS 15-42 mm diam, conical to broadly so, with a slight broad obtuse umbo in age or upon expansion, margin incurved in youth, later decurved; velipellis absent, disc smooth and unbroken, surface dry, not lubricous, radially rimulose to rimose, fibrillose towards the margin, on occasion torn there; Buffy Yellow, pale yellow to olive yellow, or straw yellow almost throughout (2.5Y 8/6-7/4-6/6) or with an isabelline or light olive brown margin (2.5Y 5/6-6/6), or at times isabelline almost throughout or bicolorous with a fulvous disc and isabelline margin; thin-fleshed, up to 2 mm thick under the disc, pallid or watery gray, odor none to slightly acidulous. LAMELLAE adnexed to subfree, very close, c. 40-46 L, with several tiers of lamellulae, light gray to very pale brown (10YR 7/2-7/3), pale brown to yellowish brown or brown (10YR 6/3-5/3), (sub)ventricose; edges pallid, indistinctly fimbriate. STIPE 25-53 (-70) × 2-5 mm at the apex, terete, even to the slightly to abruptly marginate basal bulb, this up to 10 mm wide, surface pruinose entire length with a silky satiny appearance, pallid or virtually white or with a pink tinge; context solid, brittle, pallid.

SPORES 8.0-9.5-11.0 ± 0.72 × (4.8-) 5.2-6.6-8.0 (-8.8) ± 0.72 µm (n=42/3), gibbous with typically 7-10 prominent sized nodules around a polygonal or at times trapeziform outline, yellowish-brown. BASIDIA 26-30 × 9-11 µm, 4-sterigmate, clavate, hyaline. PLEUROCYSTIDIA 52-65 × 18-28 µm, ventricose to broadly lageniform, generally tapered at both ends but often lacking a distinct neck and pedicel; very thick-walled, walls -5.0 µm thick, hyaline; apices crystalliferous. CHEILOCYSTIDIA similar to pleurocystidia but smaller, mixed with hyaline paracystidia. CAULOCYSTIDIA similar to pleurocystidia, descending the entire length of the stipe in scattered, dense clusters, often mixed with cells of intermediate size and shape. PILEIPELLIS a cutis of cylindric hyphae, 5-10 µm wide, smooth or weakly incrusted, light yellowish brown in mass, tramal hyphae with conspicuous ochraceous refractive hyphae present. CLAMPS present.

HABITAT: on soil in rainforest under Nothofagus cunninghamii, March to May. Reported in Victoria under Nothofagus and in wet Eucalyptus forest.

SPECIMENS EXAMINED: AUSTRALIA: TASMANIA. In rainforest, Creepy Crawly Nature Trail, Southwest National Park, 16-Mar-2002, leg. G. Gates & D. Ratkowsky (I64, TENN065737, HO); on soil in rainforest under Nothofagus cunninghamii, 800 m elev, Mt. Michael Track, the Blue Tier, 22-May-2010, leg. G. Gates & P.B. Matheny (PBM3387, TENN065735); same locality as above, 22-May-2010, leg. G. Gates & P.B. Matheny (PBM3388, TENN065736); on soil under Nothofagus cunninghamii in rainforest, 800 m elev, Ralphs Falls, West Pyengana, 23-May-2010, leg. G. Gates, D. Ratkowsky, & P.B. Matheny (PBM3392, TENN065738); same locality as above under Nothofagus cunninghamii, 23-May-2010, leg. G. Gates, D. Ratkowsky, & P.B. Matheny (PBM3393, TENN065739); same locality as above under Nothofagus cunninghamii, 23-May-2010, leg. M. Pilkington, P.B. Matheny (PBM3394, TENN065745); on soil in rainforest under Nothofagus cunninghamii, Weldborough Pass, near Pyengana, 24-May-2010, leg. G. Gates & P.B. Matheny (PBM3405, TENN065740); along track on soil in rainforest under Nothofagus cunninghamii, Vale of Belvoir, 30 km outside Gowrie Park, 25-May-2010, leg. P.B. Matheny (PBM3412, TENN065741). VICTORIA. Under Nothofagus cunninghamii, Melba Gully State Park, west of Apollo Bay, 3-May-1995, leg. N.L. Bougher, R. Vilgalys, S. Bolsenbroek, & M. Brundrett (E5353, PERTH).

COMMENTS: Inocybe scissa can be identified by the following combination of features: the buffy or straw yellow, rimose to rimulose pileus; entirely white pruinose stipe that at times has a pink tinge; distinct marginate-bulb at the base of the stipe; nodulose spores; broadly inflated pleurocystidia; and occurrence in temperate Australian rainforest. The species is foremost a Nothofagus-associate first described from New Zealand by Horak (1977) but also recorded under Leptospermum. Here we report this species from Tasmania for the first time where it is commonly encountered in rainforest habitat under Nothofagus cunninghamii. Inocybe scissa was first reported from Australia in Victoria by May (1989) and Ford & May (1998) in wet forests there. We cite an additional collection here from temperate rainforest (i.e., Nothofagus) habitat in Victoria (E5353, PERTH). The description of New Zealand material features a more distinctive rimose pileus than Tasmania material. Our observations of Tasmanian collections also often lack pink tinges to the color of the stipe (that is, they are often simply white). Comparison with materials labeled I. scissa from New Zealand has been problematic due to misidentification of some materials (PDD71140, now regarded as I. horakomyces Garrido; PDD75859, originally determined as I. graveolens); at this time, we conservatively apply the name here until bona fide I. scissa, including field notes, is studied.

There are several closely related species to I. scissa that occur in New Zealand and/or temperate Australia and these obviously can be confused. Inocybe horakomyces (=Astrosporina avellana E. Horak; the name I. avellana P. Kumm. is already taken in Inocybe) was described from New Zealand but has a light brown pileus and cystidia that are not as inflated in size (Horak 1977); this species has yet to be reported from Australia. Another includes I. graveolens (E. Horak) Garrido, originally described from New Zealand, which differs by the reddish brown pileus, strong spermatic odor, and association with Leptospermum in New Zealand (Horak 1977). Collections very similar to I. graveolens may also be present in southeastern Australia. Inocybe straminea (E. Horak) Garrido is entirely yellow throughout (pileus, lamellae, and stipe are all yellow) and is reported only from sand dunes under Leptospermum in New Zealand (Horak 1977). As far as we are aware, this species is known only from the type. Inocybe calopedes Matheny & Bougher (=I. discissa (Cleland) Grgur., non descissa (Fr.) Quél.) differs readily by the reddish brown pileus and lack of an odor; this species, including genetic variants, occurs in southeast and southwest Australia (Matheny & Bougher 2010).

A sample of I. scissa (PBM3394) was analyzed for presence of muscarine using a high performance liquid chromatography method and found to have large amounts of muscarine relative to other species examined (Kosentka et al., unpublished data). Australian populations should be regarded as highly toxic.


  • Horak E (1977) Fungi Agaricini Novaezelandiae VI. Inocybe (Fr.) Fr. and Astrosporina Schroeter. N.Z. J. Bot. 15: 713-747.
  • Matheny PB, Bougher NL (2010) Type studies of Inocybe from Australia. Muelleria 28: 87-104.
  • May TW (1989) Report of the F.N.C.V fungal excursions: 1986-1988. Victorian Naturalist 106: 48-58.
  • Ford S, May TW (1998) A cryptogamic extravaganza: report of the FNCV expedition 22-25 May 1998 to commemorate the centenary of Wilson’s Promontory National Park. Field Naturalists Club of Victoria, Blackburn.