Inocybe neglecta 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 : 208-210

4. Inocybe neglecta E. Horak, Matheny & Desjardin , spec. nov. Fig. 5a–g ; Pl. 2b

MycoBank MB 519916

Etymology: neglectus (Lat.), neglected.

Diagnosis: Pileus dark brown on the disc and minutely scaly, brown or greyish brown and rimose-sulcate towards the margin, surface dry. Stipe greyish brown to pale brown, minutely pruinose at the apex, base subbulbous. Odor not distinctive. Basidiospores pruniform, smooth. Pleurocystidia absent. Cheilocystidia present but inconspicuous, broadly lageniform to subutriform, thin-walled, hyaline. On soil in tropical montane forest dominated by Lithocarpus and Castanopsis in Thailand.

Holotype:— THAILAND. Chiang Mai Prov.: Hwy 1095 near 27 km marker, next to Buddhist temple, N19˚06‘ 28.8“, E98˚44‘47.3“, 1050 m elev., on soil in tropical montane forest (dominated by Lithocarpus and Castanopsis ), 12 Jun. 2006, leg. H.T. Le & D.E. Desjardin (DED8063, holotype, SFSU; isotype, ZT13022) GenBank accession no. EU600829.

Pileus 12–18 mm wide, at first obtusely conical, becoming broadly umbonate or campanulate in age, at disc dark brown (7F4–8), brown (7E6–7) or greyish brown (7D3–4) towards the conspicuously rimose-sulcate and splitting margin, umbo felty or appressed-tomentose, with a few tiny squamules on the ridges towards margin, dry, veil remnants absent; context <1 mm thick, white, unchanging upon exposure. Lamellae 40–48 reaching stipe, up to 7 lamellulae, adnexed, up to 2 mm wide, greyish brown (6D3) to brown (7E4–5), entire edges concolorous. Stipe 25–35 × 1–2 mm, central, cylindrical, ± equal, but base subbulbous, greyish brown (6–7D3) to pale brown (7D4), minutely pruinose at apex only, glabrous towards paler or white base, dry, solid; cortina absent. Odor and taste not distinctive.

Basidiospores 7.5–8.5 × 5.5–6 μm, pruniform (in side view), broadly ovoid (in front view), brown, smooth, occasionally with obscure germ pore, brown in deposit. Basidia 24–32 × 9–10 μm, 4-spored, clavate. Cheilocystidia 30–45 × 8–14 μm, inconspicuous, broadly lageniform or subutriform, wall thin, hyaline, crystals absent; paracystidia 18–25 × 10–15 μm, scattered, broadly clavate, thin-walled and hyaline. Pleurocystidia absent. Caulocystidia 30–50 × 5–8 μm, scattered, shape ranging from cylindrical to subfusoid, hyaline, thin-walled, crystals absent. Pileipellis a cutis (or trichoderm at squamules) of repent or suberect, cylindrical hyphae, 5–8 μm wide, terminal cells not differentiated, non-gelatinized wall with pale brown incrusting and parietal pigment; subpellis hyphae cylindrical, 6–10 μm wide, encrusted with brown pigment; oleiferous hyphae absent. Clamp connections present.

Habitat: On soil in tropical montane forest (dominated by Lithocarpus and Castanopsis ), 1050 m elev.

Known distribution: Northwest Thailand.

Notes: The most distinctive macromorphological characters of I. neglecta are the strongly rimose margin of the pileus, the subbulbous base of the mostly glabrous stipe and the lack of odor. Microscopically, this species is readily recognized by the rather large pruniform-ovoid basidiospores and the scattered, inconspicuous, thin-walled cheilocystidia. Typical for sect. Rimosae (Pseudosperma clade) pleurocystidia are absent. In Thailand, the type locality of this unique Inocybe is situated in tropical montane forest dominated by Lithocarpus and Castanopsis .

A multigene relaxed molecular clock analysis by Matheny et al. (2009) placed I. neglecta sister to the remaining Pseudosperma clade with significant support (Bayesian posterior probability). A similar arrangement is recovered here but with weak support ( Fig. 1 , see also Kropp et al. 2013).

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.

PLATE 2. a. Inocybe latibulosa (DED8055, holotype). b. Inocybe neglecta (DED8063, holotype). c. Inocybe errata (ZT10108, holotype). d. Inocybe proxima (DED8007, holotype). Scale bars = 10 mm. Photos a, b, d, by Dennis Desjardin, c, by Egon Horak.

FIGURE 5. Macroscopic and anatomical features for Inocybe neglecta (DED8063, holotype). a. Basidiomes. b. Basidiospores. c. Basidia. d. Cheilocystidia. e. Paracystidia. f. Caulocystidia. g. Pileipellis. Scale bars: basidiomes = 20 mm, basidiospores = 10 μm, basidia and cystidia = 20 μm, pileipellis = 40 μm. Drawings by Egon Horak.