Inocybe bicolorata E. Horak, Matheny & Desjardin, 2015

Horak, Egon, Matheny, P. Brandon, Desjardin, Dennis E. & Soytong, K., 2015, The genus Inocybe (Inocybaceae, Agaricales, Basidiomycota) in Thailand and Malaysia, Phytotaxa 230 (3), pp. 201-238 : 206

2. Inocybe bicolorata E. Horak, Matheny & Desjardin , spec. nov. Fig. 3a–e .

MycoBank: MB 519910

Etymology: bi (Lat.), two; coloratus (Lat.), colored.

Diagnosis: Pileus bicolorus with a dark fuscous disc and deep chestnut brown margin, non-scaly. Stipe smooth, non-pruinose, with lilac at the apex at least when young. Odor distinctly spermatic. Basidiospores phaseoliform. Pleurocystidia absent. Cheilocystidia short, clavate-vesiculose or subutriform, thin-walled. In tropical montane forest dominated by Quercus, Malayasia.

Holotype:— MALAYSIA. Pahang: Frazer‘s Hill, Bishop Trail , on soil in tropical montane rain forest (dominated by Quercus spp. ), N 03°42‘950‘, E 101°44‘43‘‘, 15 Jan. 2004, leg. E. & A. Horak ZT12187 ( SFSU, holotype; ZT, isotype) GenBank accession no. GQ892984, GQ892938.

Pileus 6–20 (–25) mm wide, at first conical, in age hemispherical to convex with obtuse umbo, finally umbonate-expanded, at first deep chestnut brown, disc gradually becoming dark fuscous, radially innate-fibrillose to minutely fibrillose, margin weakly splitting in old specimens, dry, young with distinctive pale fibrils from veil; KOH (5%) negative on pileus surface. Lamellae 20–28 reaching stipe, up to 5 lamellulae, adnate, ventricose, at first distinctly lilac or lilac-grey, becoming umber to pale fuscous in age, entire or minutely fimbriate edges concolorous. Stipe 20–50 × 1.5–3 mm, cylindrical, equal with slightly swollen at base, lilac at non-pruinose apex (at least in young specimens), towards base concolorous with pileus, smooth, (apart from cortina) velar fibrils present towards base of stipe, base often with whitish mycelial pad, dry, solid; cortina only distinctive in young specimens, usually present as remnants or occasionally forming submembranaceous non-persisting funnel-shaped annulus; context distinctly lilac-violet in upper half of stipe, old concolorous. Odor and taste distinctly spermatic.

Basidiospores (6.5–) 7–7.5 × 4–5 μm, phaseoliform (in side view), pale brown, smooth, thin-walled, germ pore absent, brown in deposit. Basidia 24–30 × 7–8 μm, 4-spored, subclavate or cylindrical. Cheilocystidia 20–35 × 12–20 μm, clavate-vesiculose or subutriform, hyaline, thin-walled, pigment absent. Pleurocystidia absent. Caulocystidia absent or scattered, shape and size like cheilocystidia. Pileipellis a cutis (or trichoderm) of repent (or semierect) cylindrical hyphae, 4–6 μm wide, terminal cells slender fusoid, non-gelatinized wall encrusted with yellow-brown (in 5% KOH) pigment, occasionally also with yellow-brown plasmatical pigment; subpellis hyphae cylindrical, 6–10 μm wide, entangled, wall encrusted with pigment; oleiferous hyphae absent. Clamp connections present.

Habitat: On soil among litter in tropical montane rain forest (dominated by Quercus spp. ), 1400 m elev.

Known distribution: Malaysia.

Notes: The present species is characterized by distinctive macroscopic (in young basidiomes lilac colors both on lamellae and at the stipe apex, strong spermatic odor) and microscopic features (phaseoliform basidiospores and clavate-vesiculose, thin-walled cheilocystidia). The Malaysian taxon, reported from tropical montane oak forests, is readily identified by the comparatively small basidiospores measuring 7–7.5 × 4–5 μm. Phylogenetically, I. bicolorata is nested in the Inosperma clade ( Fig. 1 ; Kropp et al. 2013) with strong support. This tropical Quercus -associated species appears related among north temperate species I. fastigiella G.F.Atk. , I. lanatodisca Kauffman , and I. maculata Boud. but with weak support. This latter mixture corresponds to a subgrouping of the Maculata clade of Larsson et al. (2009).

Figures

FIGURE 1. nLSU ML phylogeny of the Inocybaceae (with outgroups pruned) illustrating the autonomous placement and highly polyphlyetic nature of Thai and Malay species of Inocybe in bold (note that I. petchii and I. gemina are not present in the tree). Numbers above and below branches represent ML bootstrap values.

FIGURES 2–3. 2. Macroscopic and anatomical features for Inocybe spherospora (DED8059). a. Basidomes. b. Basidiospores. c. Basidia. d. Cheilocystidia. e. Pleurocystidia. f. Caulocystidia. g. Pileipellis. 3. Macroscopic and anatomical features for I. bicolorata (ZT12187, holotype). a. Basidiomes. b. Basidiospores. c. Basidia. d. Cheilocystidia. e. Pileipellis. Scale bars: basidiomes = 20 mm, basidiospores = 10 μm, basidia and cystidia = 20 μm, pileipellis = 40 μm. Drawings by Egon Horak.