Inocybaceae: Inocybe

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

PILEUS 18-45 mm wide, convex in youth becoming conical to plano-convex or plane with low, obtuse umbo, margin incurved at first, later decurved and uplifted in age; surface dry, squarrose-scaly with pyramidal-like tufts of squarrose scales at the center to imbricate-scaly, fibrillose and radially split towards the margin; sepia or dark brown overall but a lighter shade of brown beneath or between the scales and darker fibrils, dry specimens colored like I. lanuginosa; context dirty white and thin, odor and taste none. LAMELLAE adnate, close with several tiers of lamellulae, up to 4 mm wide, light gray to whitish when very young, becoming dark yellowish brown, drying rusty brown; edges pallid-fimbriate. STIPE 18-35 × 4-10 mm wide at the apex, even, central, terete, light brown to reddish brown, surface fibrillose, fibrils more dense and Sepia or dark grayish brown above the base, nowhere pruinose; cortina present when young but evanescent; context solid, colored like the pileus.

SPORES 7.8-8.6-9.7 ± 0.48 × 4.5-5.5-6.5 ± 0.44 mm, smooth, amygdaliform with bluntly pointed apices, these at times mucronate at least on lamellar mounts, yellowish brown, apiculus not very distinct. BASIDIA 25-29 × 9-10 mm, 4-sterigmate, clavate, hyaline. PLEUROCYSTIDIA 50-70 × 10-17 mm, fusiform, thick-walled, slightly thick-walled, or at times thin-walled, walls 1.0-2.5 mm thick, hyaline; apices obtuse, crystalliferous or sparsely so, at times subcapitate. CHEILOCYSTIDIA similar to pleurocystidia but shorter, mixed with hyaline paracystidia. CAULOCYSTIDIA none (that is, metuloids and cauloparacystidia absent), stipe surface with clusters of brown, incrusted caulocystidioid hairs, these generally cylindric or somewhat fusiform (largely undifferentiated end cells), lacking crystals, short septate, more prevalent and dense on lower part of the stipe. PILEIPELLIS composed of trichodermially arranged tufts of cylindric hyphae, dark yellowish brown in mass, mostly 5-12 mm wide, incrusted. CLAMPS present.

SPECIMENS EXAMINED: AUSTRALIA: AUSTRALIA CAPITAL TERRITORY. Scattered or in small clusters in lawn under scattered Eucalyptus, Australian National Botanic Gardens, 4 km NNW of Capital Hill, Canberra, 35° 18' S, 149° 06' E, 620 m elev, 26-May-1991, leg. H. Lepp (H. Lepp 546, CANB574568 [holotype]). TASMANIA. Pipeline, 26-Dec-2011, leg. G. Gates & D. Ratkowsky (I35, HO).

COMMENTS: Inocybe austrosquarrosa features smooth spores and a squarrose pileus and is known so far from two collections in southeast Australia. The species is unusual in that caulocystidia are completely lacking from the stipe. The pleurocystidia are typically fusiform and only slightly thick-walled to thin-walled with subcapitate apices at times. It could be confused with I. australiensis Cleland & Cheel, but in this latter species the stipe is pruinose at least on the upper half and metuloid caulocystidia can be easily found. The spores of I. australiensis are also shorter (6.5-7.5 × 4.0-5.0 mm) than in I. austrosquarrosa. Inocybe phaeosquarrosa E. Horak is similar to I. austrosquarrosa but differs by the scaly stipe, though the cystidia are thin-walled, and occurs in rainforest habitat on rotten wood of Nothofagus in New Zealand. Inocybe umbrosa E. Horak has a dark brown scaly pileus but differs by its entirely pruinose, reddish brown stipe and is known only from Nothofagus forests mixed with Leptospermum on soil or rotten wood.