Inocybe angustifolia (Corner & E. Horak) Garrido (1988: 120)

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 : 220-221

12. Inocybe angustifolia (Corner & E. Horak) Garrido (1988: 120) . Fig. 11a–g ; Pl. 4c–d , 8d

Basionym: Astrosporina angustifolia Corner & E. Horak in Horak (1979: 195).

Pileus 10–35 mm wide, at first obtuse conical, becoming convex with obtuse papilla, campanulate or expanded with low obtuse umbo in age, at first whitish to very pale ochre (4A3), turning yellowish (4B5–6) or pale ochre yellow in age, weakly viscid if moist, at first smooth, in age becoming innate-fibrillose and distinctly rimose at non-striate margin, occasionally with appressed squamules at disc, veil remnants absent; context whitish or pale yellow, slowly turning rust orange on bruising and on exposure. Lamellae 28–36 reaching stipe, up to 15 lamellulae, adnate (to subdecurrent), up to 4 mm wide, at first whitish or greyish yellow (4B4), becoming very pale beige brown (6D4) in age, entire edges concolorous. Stipe 20–65 × 2–3 (–4) mm, cylindrical, slender, equal, base sometimes swollen; surface dry, pruinose all over, white or pale yellowish (3–4A2–3), staining rust ochre on bruising; cortina absent; context solid, whitish or pale yellow, slowly turning rust orange on bruising and on exposure. Odor strongly spermatic. Taste spermatic or bitter-raphanoid.

Basidiospores (6.5–) 7–9 × 4.5–5.5 (–6) μm, distinctly nodulose, ovoid, yellow-brown, germ pore absent, brown in deposit. Basidia 22–28 × 6–9 μm, 4-spored, slender clavate. Cheilocystidia (35–) 40–60 (–70) × 12–18 μm, fusoid, metuloid, walls up to 2.5 μm thick at apex, hyaline, crystals present; paracystidia 15–25 × 8–12 μm, clavate to vesiculose, hyaline, thin-walled. Pleurocystidia similar to cheilocystidia. Caulocystidia similar to cheilocystidia, intermixed with clavate cells. Pileipellis a cutis (ixocutis), composed of repent, cylindrical hyphae, 3–5 μm wide, terminal cells not differentiated, weakly gelatinized wall, hyaline, thin-walled, pigment absent; subcutis hyphae shortcylindrical, 5–10 μm wide, wall occasionally up to 1.5 μm wide, weakly encrusted with yellow-brown pigment; oleiferous hyphae absent. Clamp connections present.

Habitat: Singly on (lateritic) soil in tropical montane forest dominated by Dipterocarpus , Castanopsis , Quercus , Lithocarpus , with scattered Pinus kesiya , 950–1260 m elev.

Known distribution: Papua New Guinea (type), Indonesia, Malaysia, northwest Thailand.

Specimens examined: PAPUA NEW GUINEA. Morobe District: Bulolo, Manki, on soil in tropical montane forest (dominated by Lithocarpus sp. ), 1400 m elev., leg. E. Horak (ZT72-406, holotype!). THAILAND. Chiang Mai Prov.: Chiang Mai, Doi Suthep, 19 km marker, 1260 m elev., on lateritic soil in tropical montane forest (dominated by Castanopsis , Quercus , Lithocarpus , with scattered Pinus kesiya ), 6 Jun. 2002, leg. E. & A. Horak (ZT10149) GenBank accession no. GQ892990, GQ892944; Doi Suthep National Park, Sangasabhasri Lane to Huai Kok Ma Village, N18˚48.68‘, E98˚54.60‘, on soil in tropical montane forest (dominated by Castanopsis ), 7 Jun. 2006, leg. D.E. Desjardin (DED8043, SFSU; ZT13031) GenBank accession no. EU569851; same locality and habitat, 4 Jul. 2002, leg. D.E. Desjardin (DED8139, SFSU) GenBank accession no. GQ892988, GQ892942; Hwy 1095 near 27 km marker, Pathummikaram Temple area near Ban Pha Deng, N19˚06‘28.8‘‘, E98˚44‘47.3‘‘, 1050 m elev., on soil in tropical montane forest (dominated by Dipterocarpus ), 27 Jun. 2007, leg. D.E. Desjardin (DED8146, SFSU) GenBank accession no. GQ892989, GQ892943.

Notes: The taxonomic description is presented from Thai specimens. The most distinctive characters of I. angustifolia are: a pileus (and stipe) at first whitish, pale yellow or fawn in age, narrow, densely crowded lamellae, and an entirely pruinose stipe that is cylindrical-equal or with a swollen to submarginate base. The basidiospores are relatively small, with numerous subconical or hemispherical nodules. Cheilocystidia and pleurocystidia often have yellowish parietal pigment (in 5% KOH). This species is widely distributed in Australasia and southeast Asia ( Turnbull & Watling 1999) where it is encountered in association with Dipterocarpus or Castanopsis , Lithocarpus and Quercus with scattered Pinus in tropical montane rain forest ( Horak 1980). It has been reported in association with Shorea in Malaysia ( Turnbull & Watling 1999).

Two LSU sequences correspond well with collection ZT10149. The sequence of DED8043 appears sister to this core group. Inocybe angustifolia shares pale yellow coloration and small size with I. alabamensis Kauffman , known from the southeast USA but which may be conspecific with I. paludinella (Peck) Sacc. Together with I. umbratica Quél. and a second unclarified Thai species, for which our morphological data are incomplete, these four lineages form a robust monophyletic group (91% MLBP).

Figures

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 11. Macroscopic and anatomical features for Inocybe angustifolia (ZT10149). 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.