Hebeloma flavidifolium (Corner) Beker & U. Eberh., 2021

Eberhardt, Ursula, Schuetz, Nicole, Beker, Henry J., Lee, Su See & Horak, Egon, 2021, Hebeloma in the Malay Peninsula: Masquerading within Psathyrella, MycoKeys 77, pp. 117-141 : 117

Hebeloma flavidifolium (Corner) Beker & U. Eberh. comb. nov. Figures 2A , 3 , 4 , 5

Psathyrella flavidifolia Basionym. Psathyrella flavidifolia Corner, Gdns’ Bull., Singapore 45(2): 339 (1994) [ “1993”].

Homotypic synonym.

Lacrymaria flavidifolia (Corner) Voto, Boll. Assoc. micol. ecol. Romana 107(2): 94 (2019).

Type.

Malaysia. Pahang State: Raub district, Bukit Fraser ( Fraser’s Hill), ca. 1200 m a.s.l., Quercus woodland, 25 Nov 1930, E.J.H. Corner (holotype: E! [E 00204812]; database reference HJB19600).

Description.

Basidiomes scattered. Pileus 35-105 mm wide, convex to broadly umbonate; surface dry, sometimes rugulose, occasionally striate at the margin, usually with veil remnants on the margin; cuticle color predominantly cinnamon brown to orange brown (6C5, 7C7) in the center with paler margin, dark beige to tan (5B3); pileus margin strongly involute when young, hygrophanous. Lamellae adnate, often with decurrent tooth, 2-3 mm broad, crowded, thin, with approx. 80-90 full length lamellae and 2-3 lamellules between the lamellae, off-white to cream or yellow-grey when young, later becoming more pinkish or grayish red to purplish and eventually vinaceous to purple-brown or brown following spore maturity; edges weakly fimbriate and white; the white edge remains when the basidiome is dried but the reddish brown color of the lamellae disappears with time. Stipe 50-120 mm long and with central width 5-12 mm, cylindrical sometimes tapering or clavate towards the base, not rooting, occasionally with mycelial cords at the base; white or alutaceous; surface dry, fibrillose, pruinose in the upper part, not discoloring with handling, becoming hollow with age. Flesh whitish, hardly discoloring where bruised. Odor indistinct to raphanoid; taste bitter. Spore vinaceous cinnamon becoming chocolate brown. Exsiccata with no particular characteristics.

Basidiospores based on at least 50 spores from each of three collections, 5% to 95% percentile range 8.9-11.4 × 5.6-7.1 µm, with median 9.7-10.6 × 6.1-6.7 µm and av. 9.6-10.6 × 6.1-6.6 µm with av. S. D. length 0.47 µm and width 0.33 µm; Q value 5% to 95% percentile range 1.43-1.72, with median 1.53-1.58 and av. 1.53-1.59 with av. S. D. 0.07; amygdaloid, occasionally limoniform with small apiculus and rounded apically, with a distinct thinning of the apical wall, without guttules, usually very strongly ornamented, warty, with a strongly and distinctly loosening perispore on almost every mature spore and strongly dextrinoid, becoming medium brown in Melzer’s reagent, sometimes deep brown, ((O3) O4; P3; D3 (D4)); spore color under the light microscope distinctly brown. Basidia av. dimensions 19-33 × 6-9 µm, cylindrical to clavate, without pigmentation, 4-spored. Cheilocystidia irregular, cylindrical to ventricose, often pyriform or napiform often mucronate or rostrate, even lanceolate (as shown in Fig. 3c for example) sometimes septate with width near apex (excluding any rostrum) 5% to 95% percentile range 5.4-10.2 µm, with median 5.6-8.4 µm and av. 5.7-8.6 µm with av. S.D. 0.94; and av. overall measurements 26-29 × 5.7-8.6 × 6.6-9.7 × 5.8-7.5 µm av. Cheilocystidium av. ratios A/M: 0.9-0.91, A/B: 0.77-1.6, B/M: 0.61-1.35. Pleurocystidia present, and abundant, and similar to cheilocystidia, but more often mucronate. Caulocystidia resembling the cheilocystidia but tending to be more cylindrical and longer up to 60 µm. Pileipellis an ixocutis with a very thin epicutis only about 30 µm thick, with gelatinized hyphae, sometimes encrusted, up to 6 µm wide. Subcutis, below the epicutis, orange-brown and the trama below the cutis made up of isodiametric cells up to 17 µm wide. Clamp connections at septa present throughout the basidiome.

Distribution.

So far known only from Bukit Fraser ( Fraser’s Hill), Malaysia.

Ecology.

The recent collections were found scattered in lowland dipterocarp-oak woodland on the side of the path in tropical rain forest with Quercus .

Additional material examined.

Malaysia. Pahang State: Raub district, Bukit Fraser ( Fraser’s Hill), Jalan Girdle, ca. 1000 m a.s.l., 3.71°N, 101.74°E, Quercus woodland, 26 Apr. 2010, E. Horak 13406 (collection E. Horak at ZT, FRIM [FRIM 62499]; database reference HJB13505); Pahang State: Raub district, Bukit Fraser ( Fraser’s Hill), Jalan Girdle, ca. 1000 m alt., 3.71°N, 101.74°E, Quercus woodland, 26 Apr. 2010, E. Horak 13404 (collection E. Horak at ZT, FRIM [FRIM 62500]; database reference HJB13504).

Remarks.

Given Corner’s original description almost totally lacked any microscopic information, we present a full description here based on the holotype plus two more recent collections from roughly the same location, both collected by E. Horak. Morphologically, this species most closely resembles Hebeloma angustilamellatum , originally described from the Yunnan province of China ( Yang et al. 2005) and also recorded from northern Thailand and Laos (Table 1 , Fig. 1 ), from which it can be distinguished morphologically by the very strongly ornamented spores (O4), conspicuous even without immersion (those of H. angustilamellatum are O3, so distinctly ornamented but not conspicuous without immersion) and the less conspicuous annulus on the fibrillose stipe of mature basidiomes ( H. angustilamellatum has a more persistent annulus, always present, and a stipe, with scattered fibrillose scales, consistently present.) Phylogenetically, based on ITS and MCM7, H. flavidifolium is a sister species of H. ifeleleretorum described from Samoa, but all three form a cluster in Fig. 1 that received full posterior probability and 92% bootstrap support.

Figures

Figure 1. ML topology of concatenated ITS and MCM 7 sequences of Hebeloma and Alnicola. Flammula alnicola is used for rooting purposes. Bootstrap support based on 500 replicates and posterior probabilities based on a BI analysis are indicated at the branches. Assignment of species to sections follows Beker et al. (2016). Sequences in red are from Malaysian collections discussed in this paper. T indicates type collections. Thick branches indicate full support. AS - Asia, EU - Europe, NA - North America, O - Oceania, gr. - group.

Figure 2. Macroscopic features A Hebeloma flavidifolium (E. Horak 13406) B H. lactariolens (E. Horak 13381) C H. parvisporum (E. Horak 12796) D H. radicans holotype (E. Horak 13265). Photographs E. Horak.

Figure 3. Microscopic features of Hebeloma flavidifolium holotype (E 00204812) A spores in Melzer's reagent x 1600 B spore ornamentation in Melzer's reagent x 1600 C cheilocystidia in Melzer's reagent x 500 D cheilocystidia in Melzer's reagent x 1000 E cheilocystidia in KOH x 1000 F pleurocystidia in KOH x 1000. Scale bars: 10 µm (A-F). Photographs H. J. Beker. G Exsiccata (a section of photograph from http: // data. rbge. org. uk / herb / E 00204812 provided by the Royal Botanic Garden Edinburgh).

Figure 4. Microscopic features of Hebeloma flavidifolium (E. Horak 13406) A spores in Melzer's reagent x 1600 B spore ornamentation in Melzer's reagent x 1600 C cheilocystidia in KOH x 500 D cheilocystidia in KOH x 1000 E basidium in KOH x 1000 F pleurocystidia in KOH x 1000 G caulocystidium in KOH x 1000 H ixocutis section (showing thin gelatinous epicutis) in KOH x 125 I epicutis hyphae in KOH x 500 J subcutis below epicutis in KOH x 500. Scale bars: 10 µm, 100 µm (H). Photographs H. J. Beker.

Figure 5. Microscopic features of Hebeloma flavidifolium (E. Horak 13406) A spores x 2000 B basidia x 1000 C cheilocystidia x 1000 D pleurocystidia x 1000 E pileipellis (section of subcutis below epicutis) x 500. Scale bar: 10 µm x 2000, 20 µm x 1000 and 40 µm x 500. Drawing E. Horak.