Hebeloma radicans E. Horak, 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 radicans E. Horak, Beker & U. Eberh. sp. nov. Figures 2D , 8 , 9

Diagnosis.

The combination of a deeply rooting stipe, about 60 full length lamellae (from stipe to margin of pileus) and spores where almost every spore has a strongly loosening perispore forming a clear layer around the spore, separate this taxon from all other members of H. sect. Porphyrospora , as does the ITS-sequence.

Type.

Malaysia. Johor State: Kluang district, Endau-Rompin Peta, Endau-Rompin (Johor) National Park, Kampung-Peta, trail to Kuala Marong, ca. 50 m a.s.l., 2.52°N, 103.36°E, on soil in lowland dipterocarp-oak forest, 3 Sept 2009, E. Horak, 13265 (holotype: collection E. Horak at ZT; isotype: FRIM [FRIM 62930]; database reference HJB13364, ITS GenBank Acc. No.: MT832018).

Description.

Basidiomes scattered. Pileus 37-64 mm wide, convex to broadly umbonate; surface dry or slightly viscid, without veil remnants on the pileus; cuticle color predominantly cream to pale buff (4A3, 4A4) in the center with paler margin, off-white to pale cream (4A2); pileus margin entire, hygrophanous. Lamellae adnate, moderately dense, thin, with approx. 60 full length lamellae and 2-3 lamellulae between the lamellae, off-white to cream when young, later pinkish or grayish red to purplish and eventually vinaceous to purple-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 160-194 mm long (including the ‘root’) and with central width 4-9 mm, cylindrical, distinctly and deeply rooting, white or alutaceous; surface dry, fibrillose, pruinose in the upper part, discoloring with handling and age. Flesh whitish, hardly discoloring where bruised. Smell fragrant; taste bitter. Spore deposit porphyry-brown (10E4). Exsiccata with no particular characteristics.

Basidiospores based on n = 94 spores of the holotype, 5% to 95% percentile range 8.7-10.2 × 5.6-6.6 µm, with median 9.5 × 6.2 µm and av. 9.5 × 6.2 µm with S. D. length 0.47 µm and width 0.34 µm; Q value 5% to 95% percentile range 1.43-1.65, with median 1.53 and av. 1.54 with S. D. 0.07; amygdaloid, with small apiculus and rounded apically, with a distinct thinning of the apical wall and never any sign of papilla, without guttules, usually very strongly ornamented, warty, with a strongly and distinctly loosening perispore on almost every mature spore (almost forming a uniform layer around the spore and making measurement quite difficult at times) and very strongly dextrinoid, immediately becoming deep and intensely red-brown in Melzer’s reagent, (O4; P3; D4); spore color under the light microscope distinctly brown. Basidia 21-29 × 6-8 µm, with av. 24.3 × 7.2 µm, cylindrical to clavate, without pigmentation, 4-spored. Cheilocystidia ventricose, primarily pyriform often mucronate or rostrate with width near apex (excluding any rostrum) 5% to 95% percentile range 5-8 µm, with median 6.4 µm and av. 6.5 µm with S.D. 1.06; and av. overall measurements 24 × 6.5 × 9.9 × 8.3 µm av. Cheilocystidium av. ratios A/M: 0.66, A/B: 0.79, B/M: 0.84. Pleurocystidia present, and abundant, and similar to cheilocystidia. Caulocystidia resembling the pleurocystidia but tending to be more cylindrical and longer. Pileipellis an ixocutis with a very thin epicutis only about 20 µm thick, with gelatinized hyphae up to 5 µm wide. The cutis below the epicutis is orange-brown and the trama below the cutis is made up of isodiametric cells up to 25 µm wide. Clamp connections at septa present throughout the basidiome.

Distribution.

Only known from the type locality in Endau-Rompin (Johor) National Park, Malaysia.

Ecology.

Scattered in lowland dipterocarp-oak woodland on the side of the path.

Etymology.

From ' Hebeloma radicans ', meaning rooting, to emphasize this character of the species.

Remarks.

Hebeloma radicans with its vinaceous colored lamellae when mature and the porphyry colored spore print which turns brown with time, is a typical member of H. sect. Porphyrospora . The highly ornamented and highly dextrinoid spores are often seen in taxa of this section; while the consistently loosening perispore is also a common feature of a number of the taxa within this section, the regularity and presentation of the perispore is atypical and very distinctive. The rooting stipe is also unusual; while we have recorded rooting stipes in other members of this section, namely: H. lactariolens , H. parvisporum , and H. victoriense , in these cases it is a shallow root occurring infrequently and not on every basidiome. The rooting stipe of H. radicans is deep and more reminiscent of H. radicosum . This long rooting stipe should be sufficient to distinguish this species from other described members of this section, but taken together with the spore properties and also the moderately dense (but not crowded) lamellae (approx. 60 full length lamellae), assuming these characters are constant, this taxon is clearly distinct. In Fig. 1 as in the BI reconstruction, H. radicans is sister to the Oceanic H. aminophilum group clade, but this relationship is not supported. The ITS differs by at least 2.2% from other members of H. sect. Porphyrospora ; there are many species in Hebeloma that are less distant from each other ( Beker et al. 2016).

While, to date, we only have one collection of this species, given its morphological differences and molecular distinctness, we are confident that this taxon is different from any other described within Hebeloma and we hope that its publication will encourage its rediscovery. It is of course possible that it has been confused with other genera, e.g. Psathyrella , as was the case with other Malay Peninsula collections as described here, but thus far we have not been able to find any evidence of this.

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 8. Microscopic features of Hebeloma radicans holotype (E. Horak 13265) A spores in KOH x 1600 B spore ornamentation in KOH x 1600 C cheilocystidia and basidium in KOH x 1000 D cheilocystidia and basidium in KOH x 1000 E pleurocystidia in Melzer's reagent x 1000 F basidia in KOH x 1000 G pleurocystidia in KOH x 500 H sectional view of ixocutis showing thin gelatinous epicutis in KOH x 125 I sectional view of subcutis and trama below subcutis in KOH x 500 J sectional view of trama below subcutis in KOH x 500. Scale bars: 10 µm, 100 µm (H). Photographs H. J. Beker.

Figure 9. Microscopic features of Hebeloma radicans holotype (E. Horak 13265) A spores x 2000 B basidia x 1000 C cheilocystidia x 1000. Scale bar: 10 µm x 2000, 20 µm x 1000 and 40 µm x 500. Drawing E. Horak.