Hebeloma ambustiterranum A. Kong & Beker, sp. nov.

Eberhardt, Ursula, Kong, Alejandro, Montoya, Adriana, Schuetz, Nicole, Bartlett, Peter & Beker, Henry J., 2022, Not (only) poison pies - Hebeloma (Agaricales, Hymenogastraceae) in Mexico, MycoKeys 90, pp. 163-202 : 163

Hebeloma ambustiterranum A. Kong & Beker, sp. nov.

Figs 6 , 7

Type.

Mexico. Tlaxcala: La Malinche National Park , 19.2749°N, 97.9825°W, alt. approx. 2800 m, on burnt soil in coniferous woodland under Pinus montezumae and P. teocote , 8 Jul 2017, H. J. Beker HJB16802 (holotype TLXM 6155; isotype BR 5020224874626V) ; GenBank ITS ON202501 .

Diagnosis.

The small ellipsoid, non-dextrinoid, almost smooth basidiospores (on average 8.0-10.2 × 5.6-6.5 µm) and at least 50 full length lamellae distinguish this species from all other known North American Hebeloma species and the ITS sequence differentiates this species from all other known species, worldwide.

Etymology.

From ambustus (Latin adj.) meaning scorched, terra (Latin n.) meaning soil and the Latin suffix - anum indicating position to indicate growing on scorched soil. In Mexico, the local people burn the ground in the pine forests to encourage the growth of this mushroom, which they regard as an excellent edible mushroom. The local people refer to it in Nahuatl as the xolete de ocoxal (or ocoxalnanacatl), the mushroom of the pine needles from Chamusquinero, meaning from burnt ground.

Description.

Pileus (12) 16-45 (52) mm diameter, usually umbonate or subumbonate, rarely convex or applanate; margin usually entire, sometimes involute particularly when young, often with remains of the universal veil, occasionally spotting, not hygrophanous; usually almost unicolored with color at center usually cream to ochraceous or clay-buff but may occasionally be darker, honey to sepia or umber, usually a little paler at the margin. Lamellae emarginate, white, cream to brown, with a weak white fimbriate edge sometimes visible and without droplets, number of full-length lamellae 50-74. Stipe (23) 24-60 (75) mm long, 3-8 (10) mm diameter at median, cylindrical, surface cream, ivory to pale brown but occasionally discoloring from the base upwards, sometimes strongly, fibrillose, at apex pruinose; base with white mycelium. Partial veil present on young specimens, whitish at first, before basidiospores mature, and often clear fibrils remaining on the stipe and pileus. Context in pileus white to cream, firm, in stipe stuffed, becoming hollow with age; taste not recorded, smell occasionally odorless but usually raphanoid, sometimes strongly so or with cacao components. Spore deposit color clay-buff.

Basidiospores based on n = 146 spores of the holotype, 5% to 95% percentile range 7.7-9.8 × 5.5-7.0 µm, with median 8.9 × 5.9 µm and av. 8.9 × 6.0 µm with S.D. length 0.68 µm and width 0.44 µm; Q value 5% to 95% percentile range 1.25-1.63, with median 1.48 and av. 1.47 with S.D. 0.11; spore size based on 33 collections medians 7.8-10.3 × 5.5-6.4 µm and av. 8.0-10.2 × 5.6-6.5 µm with av. S.D. length 0.61 µm and width 0.35 µm, av. Q 1.36 -1.61, ellipsoid or ovoid, with small apiculus, apex round or subacute, with a distinct thinning of the apical wall, guttulate with one or sometimes more oily drops, usually almost smooth even under immersion, with perispore not loosening, almost totally non-dextrinoid with just an indistinct brownish tint in Melzer’s reagent (O1; P0; D1); pale yellow to brown in KOH. Basidia 25-34 × 6-8 µm, with av. Q 3.7-4.4, cylindrical to clavate, hyaline, 4-spored. Cheilocystidium width near apex holotype 5% to 95% percentile range 3.5-5.3 µm, with median 4.3 µm and av. 4.3 µm with S.D. 0.63 µm; across 33 collections median 4.1-5.4 µm and av. 4.1-5.1 µm; examining approx. 20 selected cheilocystidia of each of the 33 collections yields a range for the avs. of 35-55 × 4.1-5.1 × 4.2-5.1 × 7.1-9.9 µm and 35 × 4.3 × 4.2 × 7.3 µm av. for holotype; av. ratios A/M: 0.96-1.15, A/B: 0.51-0.70, B/M: 1.55-2.31, mainly swollen in the lower half, some ventricose or lageniform, often with one or two septa, rarely geniculate or with some thickening of the median wall, hyaline. Pleurocystidia absent. Caulocystidia similar to cheilocystidia but more cylindrical and larger, up to 140 μm. Pileipellis an ixocutis; epicutis up to 100 µm thick, with gelatinized, often encrusted hyphae up to 6 µm wide; subcutis yellow and the trama below the cutis made up of cylindrical or occasionally ellipsoid cells up to 14 µm wide. Clamp connections present throughout the basidiome.

Ecology and distribution.

In temperate coniferous woodlands on burnt ground with Pinus and Quercus . Growth habit usually scattered, rarely solitary or caespitose. To date, all collections of Hebeloma ambustiterranum recorded from Mexico at latitudes between 19°N and 20°N and altitudes above 2000 m.

Additional collections examined.

Mexico. Mexico City: Municipality of Milpa Alta, approx. 19.1942°N, 99.0267°W, alt. approx. 2400 m, 4 Jul 2011, R. Vanegas-Enriquez (TLXM RVE042, HJB17734). Municipality of Milpa Alta, approx. 19.1942°N, 99.0267°W, alt. approx. 2400 m, 16 Jul 2011, R. Vanegas-Enriquez (TLXM RVE049, HJB17735). Municipality of Milpa Alta, approx. 19.1942°N, 99.0267°W, alt. approx. 2400 m, 21 May 2013, A.C. López (TLXM ACL-MA-085, HJB17736). Puebla: Municipality of Acajete, La Malinche National Park, north of Santa Isabel Tepetzala, approx. 19.1471°N, 97.924°W, alt. approx. 2600 m, on soil in woodland under Pinus sp., 15 Jul 1998, R. Reyes-Lopez (TLXM RL1-01, HJB16780). Municipality of Acajete, La Malinche National Park, 4 km north of Santa Isabel Tepetzala, approx. 19.1471°N, 97.9239°W, alt. approx. 2600 m, on soil in woodland under Pinus sp., 29 Jul 1998, R. Reyes-López (TLXM RL2-7, HJB16765). Tlaxcala: La Malinche National Park, 19.2742°N, 97.9833°W, alt. approx. 2850 m), on burnt soil in coniferous woodland under Pinus montezumae and Pinus teocote , 8 Jul 2017, Forayer (TLXM HJB16799). La Malinche National Park, 19.2744°N, 97.9831°W, alt. approx. 2850 m, on burnt soil in coniferous woodland under Pinus montezumae and Pinus teocote , 8 Jul 2017, L. Davies (TLXM HJB16800). La Malinche National Park, 19.2743°N, 97.9829°W, alt. approx. 2840 m 8 Jul 2017, L. Davies (TLXM HJB16801), on burnt soil in coniferous woodland under Pinus montezumae and Pinus teocote . La Malinche National Park, 19.2749°N, 97.9820°W, alt. approx. 2830 m, 8 Jul. 2017, A. Montoya-Esquivel, A. Kong (TLXM HJB16803), on burnt soil in coniferous woodland under Pinus montezumae and Pinus teocote . La Malinche National Park, 19.2752°N, 97.9820°W, alt. approx. 2830 m, on burnt soil in coniferous woodland under Pinus montezumae and Pinus teocote , 8 Jul 2017, A. Kong (TLXM HJB16804). La Malinche National Park, 19.2753°N, 97.9823°W, alt. approx. 2830 m, on burnt soil in coniferous woodland under Pinus montezumae and Pinus teocote , 8 Jul. 2017, A. Montoya-Esquivel, A. Kong (TLXM HJB16805). La Malinche National Park, 19.2751°N, 97.9825°W, alt. approx. 2830 m, on burnt soil in coniferous woodland under Pinus montezumae and Pinus teocote , 8 Jul 2017, A. Montoya-Esquivel, A. Kong (TLXM HJB16806). La Malinche National Park, 19.2754°N, 97.9824°W, alt. approx. 2830 m, on burnt soil in coniferous woodland under Pinus montezumae and Pinus teocote , 8 Jul 2017, H. J. Beker (TLXM HJB16807). La Malinche National Park, 19.2755°N, 97.983°W, alt. approx. 2830 m, on burnt soil in coniferous woodland under Pinus montezumae and Pinus teocote , 8 Jul 2017, A. Montoya-Esquivel, A. Kong (TLXM HJB16808). La Malinche National Park, 19.2652°N, 97.9744°W, alt. approx. 2825 m, on soil in coniferous woodland ditch under Pinus teocote , 9 Jul 2017, A. Montoya-Esquivel (TLXM HJB16818). Municipality of Huamantla, La Malinche National Park, Los Pilares, approx. 19.3184°N, 97.9233°W, alt. approx. 2500 m, on soil in woodland under Pinus sp., 2 Aug 1991, A. Montoya-Esquivel (TLXM AME1048, HJB16788). Municipality of Nanacamilpa, 19.4925°N, 98.5778°W, alt. approx. 2725 m, on burnt soil and litter in coniferous woodland under Pinus montezumae , 6 Jul 2017, Forayer (TLXM HJB16747). Municipality of Nanacamilpa, 19.4923°N, 98.5783°W, alt. approx. 2730 m, on burnt soil and litter in coniferous woodland under Pinus montezumae , 6 Jul 2017, A. Kong (TLXM HJB16748). Municipality of Nanacamilpa, road from Nanacamilpa to Tepuente, 19.4922°N, 98.5783°W, alt. approx. 2730 m, on burnt soil and litter in coniferous woodland under Pinus montezumae , 6 Jul 2017, A. Montoya-Esquivel (TLXM HJB16749). Municipality of Nanacamilpa, road from Nanacamilpa to Tepuente, 19.4928°N, 98.5792°W, alt. approx. 2725 m, on burnt soil and litter in coniferous woodland under Pinus montezumae , 6 Jul 2017, L. Davies (TLXM HJB16750). Municipality of Nanacamilpa, 19.4928°N, 98.5792°W, alt. approx. 2725 m, on burnt soil and litter in coniferous woodland under Pinus montezumae , 6 Jul 2017, L. Davies (TLXM HJB16751). Municipality of Nanacamilpa, 19.4933°N, 98.5791°W, alt. approx. 2725 m, on burnt soil and litter in coniferous woodland under Pinus montezumae , 6 Jul 2017, L. Davies (TLXM HJB16752). Municipality of Nanacamilpa, 19.4935°N, 98.579°W, alt. approx. 2725 m, on burnt soil and litter in coniferous woodland under Pinus montezumae , 6 Jul 2017, L. Davies (TLXM HJB16753). Municipality of Panotla, San Mateo, Huexoyucan, 19.3874°N, 98.3028°W, alt. approx. 2485 m, on soil in deciduous woodland under Quercus sp., 10 Jul 2017, H. J. Beker (TLXM HJB16820). Municipality of Santa Ana Chiahutempan, La Malinche National Park, Surroundings of San Pedro Tlalcuapan, approx. 19.2152°N, 97.9841°W, alt. approx. 3100 m, on soil, 18 Jul 1998, A. Montoya-Esquivel (TLXM AME1652, HJB16766). Municipality of Tlaxco, north of El Rosario, El Rodeo, approx. 19.3395°N, 99.3605°W, alt. approx. 3100 m, on soil in woodland under Pinus sp. and Quercus sp., Jun 1991, A. Kong (TLXM AK1925, HJB16787). Municipality of Tlaxco, north of El Rosario, El Rodeo, approx. 19.2153°N, 97.9841°W, alt. approx. 3100 m, on soil in woodland under Pinus sp. and Quercus sp., 10 Jul 1991, A. Kong (TLXM AK1972, HJB16790). Municipality of Trinidad Sánchez Santos, La Malinche National Park, east of Javier Mina, approx. 19.2152°N, 97.9841°W, alt. approx. 3100 m, on soil, 21 May 1994, Hernandez-Valencia (TLXM HV6, HJB16778). Municipality of Trinidad Sánchez Santos, La Malinche National Park, east of Javier Mina, approx. 19.2153°N, 97.9841°W, alt. approx. 3100 m, on soil in woodland under Alnus sp. and Pinus sp., 3 Jul 1998, A. Montoya-Esquivel (TLXM AME1643, HJB16781). Tlaxcala City, mushrooms bought at the Tlaxcala market, 10 Jul 1999, A. Montoya-Esquivel (TLXM AME1713, HJB16764). Tlaxcala City, bought in market at Tlaxcala, collected from La Malinche National Park, 19.3218°N, 98.2387°W, alt. approx. 2160 m, 8 Jul 2017, M.F.M. Aguilar (TLXM HJB16809). Tlaxcala City, bought in market at Tlaxcala, collected from La Malinche National Park, 19.3218°N, 98.2388°W, alt. approx. 2160 m, 8 Jul 2017, M.F.M. Aguilar (TLXM HJB16810).

Remarks.

With its small ellipsoid, non-dextrinoid basidiospores and cheilocystidia swollen in the lower half, often lageniform or ventricose, this taxon clearly belongs to Hebeloma sect. Hebeloma and is closely related to the complex of species around H. mesophaeum . The close, but not crowded, lamellae with more than 50 full length lamellae rules out H. excedens and H. mesophaeum , both of which are widespread throughout North America ( Eberhardt et al. 2022a). Indeed, were this mushroom collected in Europe, and the key of Beker et al. (2016) applied, this would key out to H. subtortum . Hebeloma subtortum is most common in southern Europe, growing with lowland pines, and not known from North America. Within North America, no known taxon in H. sect. Hebeloma with such small ellipsoid spores has this number of full-length lamellae, making these characters sufficient for its determination.

Fig. 6D-E show this mushroom for sale in local markets of Tlaxcala, where it is regarded as a prized edible mushroom known as hongo de ocote (ocote mushroom) in Spanish ( Montoya et al. 2002). It is gathered from the temperate pine woodlands at altitudes of 2000 m and above. The local people burn the ground in the pine forests, ahead of the growing season, to encourage the growth of this mushroom. Frequent, controlled fires prevent the development of hot fires that would also damage the pines and pine roots, which are required for the fungi to grow. It is referred to in Nahuatl by several names, for example as the Xolete de ocō-xāl or ocō-xāl-nanácatl ( ocō-xālli = pine-litter; mushroom growing in ocō-xāl - the mushroom of the pine needles), rastrojo-nanácatl (mushroom growing on stubble), ocochalero, ocotero, ocoxal, ocochal, cholete de ocote, nixtamalero or as chamusquinero, meaning from burnt ground ( Estrada-Martínez et al. 2009; Reyes-López et al. 2020; Viveros-Assad et al. 2019). It is likely the same species as mentioned by Guzmán (1977) as “joletes” in Spanish, described as commonly sold in the Amecameca market, where it is recommended to boil them and then discard the water so that they are safe for consumption.

Figures

Figure 6. Hebeloma ambustiterranum A-C basidiomata A holotype TLXM 6155 (HJB 16802) B TLXM HJB 16803. C TLXM HJB 16805 D mushroom vendor in the market of Tlaxcala City E H. ambustiterranum sold in the market of Tlaxcala City. Photos A-D H. J. Beker E A. Montoya.

Figure 7. Holotype of Hebeloma ambustiterranum TLXM 6155 (HJB 16802) A basidiospores x 1600 B spore ornamentation x 1600 C basidiospores in Melzer's reagent x 1600 D-E cheilocystidia x 1000 F basidia x 1000 G cheilocystidia on lamella edge x 500 H caulocystidia x 500 I Cutis x 125. All in KOH, except C. Scale bars: 5 µm (A-F); 10 µm (G-J); 50 µm (K). Photos H. J. Beker.