Inocybe thailandica 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 : 218-220

11. Inocybe thailandica E. Horak, Matheny & Desjardin , spec. nov. Fig. 10a–i ; Pl. 4a–b , 8c

MycoBank MB 519922

Etymology: thailandicus (Lat.), referring to the type locality situated in Thailand.

Diagnosis: Pileus dark brown at the center, pale brown towards the margin, disc velvety or with small, recurved scales. Stipe slender, base equal or slightly enlarged, pruinose at the apex, glabrous elsewhere, light brown above, brown or dark brown below. Odor not distinctive. Basidiospores 10–12 μm wide, spinose, globose or broadly ovoid. Cheilocystidia, pleurocystidia, and caulocystidia 20–40 (–45) × 6–17 (–20) μm, broadly clavate or utriform, walls hyaline, up to 1.5 μm thick at apex. In tropical montane forest dominated by Castanopsis , 950–1100 m elev., Thailand.

Holotype:— Thailand. Chiang Mai Prov.: Hwy 1095, near Buddhist temple, at 27 km marker, N19˚06‘ 28.8“, E98˚44 ‘47.3“, 1050 m elev., on soil in tropical montane forest (dominated by Castanopsis ), 8 Jun. 2006, leg. H.T. Le & D. E. Desjardin ( DED8049 , SFSU, holotype; ZT13018 , isotype) GenBank accession no. GQ893013, GQ892968.

Pileus 10–25 mm wide, at first obtusely conical, becoming broadly campanulate or plano-convex umbonate, finally plano-umbonate; dark brown (6F5–8), pale brown (6E5–8) towards margin; disc velvety or with small, recurved squamules and scales, fibrillose towards striate and fibrillose-streaked margin, dry, veil remnants absent; context rather tough, 1–1.5 mm thick, whitish, unchanging upon exposure. Lamellae 36–42 reaching stipe, 3–5 lamellulae, close, adnexed to adnate, up to 4 mm wide; at first pale brown (6D3, 6D4–5) or greyish brown, becoming brown (6E5–6–8) in age; edges entire or subfimbriate, concolorous. Stipe 30–50 × 1.5–2 mm, central, cylindrical, equal or with weakly enlarged base; surface dry, minutely pruinose at apex, glabrous or sericeous elsewhere, light brown (7D4) above, brown (7E5–7) or dark brown (6–7F6–8) towards base; cortina absent; context solid or fistulose in age. Odor and taste not distinctive.

Basidiospores (9–) 10–12 μm (including rather isolated, conical-spinose projections, up to 2 μm long), globose or broadly ovoid, brown, also brown in deposit. Basidia 28–36 × 7–9 μm, 4-spored, clavate. Cheilocystidia 30–40 (–45) × 10–17 (–20) μm, broadly clavate or utriform, metuloid, walls up to 1.5 μm thick at apex, hyaline, crystals present but scattered; paracystidia 14–30 × 7–15 μm, clavate or vesiculose, walls hyaline, submetuloid at apex or thin, rarely with crystals. Pleurocystidia similar to cheilocystidia, scattered. Caulocystidia 20–36 × 6–12 μm, polymorphic, shape ranging from clavate to fusoid, hyaline, thin-walled, rarely thick at apex, crystals absent or rare. Pileipellis a trichoderm or cutis of erect or repent, cylindrical hyphae, 6–16 μm wide, terminal cells distinctly conical or fusoid, non-gelatinized wall encrusted with yellow-brown pigment; subpellis hyphae short-ovoid, 10–20 μm wide, encrusted with yellow-brown pigment; oleiferous hyphae absent. Clamp connections present.

Habitat: Singly on soil in tropical montane forest dominated by Castanopsis , 950–1100 m elev.

Known distribution: Northwest Thailand (type).

Other specimens examined: THAILAND. Chiang Mai Prov.: Mae Sae on Hwy 1095, at 55 km marker, N19˚14.326‘, E98˚38.294 ‘, 990 m elev., on soil in tropical montane forest (dominated by Castanopsis ), 3 Jun. 2006, leg. D. E. Desjardin ( DED8008 , SFSU; ZT13016 ) GenBank accession no. EU600871 ; Mae Sae on Hwy 1095, at 22 km marker, N19˚07.570‘, E98˚45.647 ‘, on soil in montane forest (dominated by Castanopsis ), 4 Jun. 2006, leg. D. E. Desjardin ( DED8020 , SFSU; ZT13017 ) GenBank accession no. GQ893014, GQ892969 .

Notes: The basidiospores and the general habit of the basidiomes of I. thailandica recall several other species recorded from localities in tropical lowland and montane habitats situated in the Malayan Region,e.g. I.aurantiocystidiata Turnbull & Watling (1995) from Malaysia, I. hydrocybiformis ( Horak 1979) from Malaysia and Singapore, and I. pahangi (Corner & E. Horak) Garrido ( Horak 1979) from Malaysia. Micromorphologically, I. thailandica is distinctly characterized by its rather short, broadly clavate or utriform cheilocystidia and pleurocystidia and ecologically by association in stands dominated by Castanopsis . In combination with the small habit of the basidiomes, this new Thai species is closely related to I. calospora Quél. (sect. Calosporae : Vauras 1989, Matheny et al. 2009). In temperate zones of Eurasia, I. calospora usually occurs in association with broadleaf trees with Alnus and Betula as its most frequent host partner ( Horak 1980, Peintner & Horak 2002, Horak 2005). In addition, the spinose basidiospores of I. thailandica are also similar or larger than the following North American taxa also belonging to the I. calospora complex, viz., I. echinocarpa Ellis & Everh. (1889) , I. rigidipes Peck (1898) , and I. subfulva Peck (1888) . Furthermore, in the montane zone of northern Argentina, a yet undescribed record of Inocybe with spinose basidiospores is found in close association with the native host partner Alnus jorullensis (Singer, BAFC T4069; Horak, ZT66-569, ZT66-571, unpublished data).

Molecular results confirm a robust alliance between I. thailandica (putative Castanopsis associate) together with Betulaceae-associates from Sweden ( I. calospora ) and Argentina ( Inocybe sp. D 25). We refer to this clade as section Calosporae ( Fig. 1 ).

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 4. a. Inocybe thailandica (DED8049, holotype). b. Inocybe thailandica (DED8008). c. Inocybe angustifolia (DED8043). d. Inocybe angustifolia (ZT10149). Scale bars = 10 mm. Photos a, b, c, by Dennis Desjardin, d, by Egon Horak.

PLATE 8. SEM images. a. Basidiospores of Inocybe hydrocybiformis (ZT10077); scale bar = 2 μm. b. Basidiospores of Inocybe stellata (ZT10097, holotype); scale bar = 2 μm. c. Basidiospores of Inocybe thailandica (DED8049, holotype); scale bar = 5 μm. d. Hymenial cystidia of Inocybe angustifolia (ZT10149); scale bar = 10 μm. e. Basidiospores of Inocybe brevisquamulosa (ZT10102, holotype); scale bar = 2 μm. f. Basidiospores of Inocybe pusillima (ZT10130); scale bar = 2 μm. g. Basidiospores of I. fragilissima (DED8061, holotype); scale bar = 2 μm. h. Basidiospores of Inocybe ornata (ZT10107, holotype); scale bar = 3 μm. i. Basidiospores of Inocybe parvibulbosa (ZT10099, holotype). Scale bar = 2 μm. Photos by U. Jauch & M Kirchmair.

FIGURE 10. Macroscopic and anatomical features for Inocybe thailandica (DED8049, holotype). a. Basidiomes. b. Basidiospores. c. Basidia. d. Cheilocystidia. e. Paracystidia and cheilocystidium. f. Pleurocystidia. g. Caulocystidia. h. Pileipellis. i. Basidiomes (ZT13017). Scale bars: basidiomes = 20 mm, basidiospores = 10 μm, basidia and cystidia = 20 μm, pileipellis = 40 μm. Drawings by Egon Horak.