Hebeloma subaustrale Murrill, Lloydia 8: 287 (1946) [1945]

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 subaustrale Murrill, Lloydia 8: 287 (1946) [1945]

Fig. 13

Hebeloma angustisporium = Hebeloma angustisporium Hesler, Kew Bulletin 32(3): 471 (1977)

Hebeloma perangustisporium = Hebeloma perangustisporium Hesler, Kew Bulletin 32(3): 478 (1977)

Type.

USA. Florida: Gainesville , Alachua Co., approx. 29.651634°N, 82.324826°W, alt. approx. 50 m, on grassy, shady soil in lawn, 30 Oct 1941, G.F. Weber (holotype FLAS-F-19345, HJB1000402; isotype TENN-F-021177, HJB1000447) .

Diagnosis.

Pileo convexo-expanso, 3-4 cm. lato, subviscido, glabro, pallido-roseo, raphanico; lamellis sinuatis, latis, confertis; sporis subovoidcis, pallidis, levibus, 8-10 × 4-4.5 μ [m]; stipite acquali, pallido, 3 × 0.5 cm.

English translation of diagnosis.

Pileus convex to applanate, 3-4 cm broad, slightly viscid, glabrous, pale pink, with raphanoid smell; lamellae sinuate, broad, crowded; spores subovoid, pale, smooth, 8-10 × 4-4.5 μ [m]; stipe equal, pale, 3 × 0.5 cm.

Description.

Pileus (20) 32-45 (46) mm diameter, usually convex, occasionally umbonate; occasionally with remains of universal veil; margin often smooth, occasionally scalloped, not hygrophanous; usually unicolor, occasionally two colors, at center cream to buff to ochraceous, often becoming paler towards the margin. Lamellae usually emarginate, occasionally adnate or adnexed; white, cream to brown, usually with white fimbriate edge, without droplets on the lamella edge, number of full-length lamellae 80-92. Stipe 30-56 (70) mm long, 5-10 (11) mm diameter at median, often clavate or cylindrical, 5-13 (14) mm wide at base, surface cream, ivory to white rarely discoloring, pruinose, particularly towards apex. Context in pileus white to cream, firm, similar color in stipe, becoming hollow with age; taste raphanoid, smell raphanoid, occasionally earthy. Spore deposit cinnamon color.

Basidiospores based on n = 63 spores of the holotype, 5% to 95% percentile range 8.4-9.8 × 4.6-5.2 µm, with median 9.0 × 4.8 µm and av. 9.0 × 4.9 µm with S.D. length 0.51 µm and width 0.18 µm; Q value 5% to 95% percentile range 1.65-2.03, with median 1.88 and av. 1.85 with S.D. 0.12; spore size based on seven collections medians 8.5-10.2 × 4.6-5.3 µm and av. 8.6-9.9 × 4.6-5.3 µm with av. S.D. length 0.657 µm and width 0.271 µm, av. Q 1.73-2.09, amygdaloid, usually fusoid, rarely navicular, with small apiculus and rounded apically, often subacute to acute, with a distinct thinning of the apical wall and no papilla, occasionally guttulate with one or sometimes more oily drops, very weakly ornamented (ornamentation only visible under immersion), with a perispore somewhat loosening, in at most a few spores, rarely not loosening or distinctly loosening, distinctly to rather strongly dextrinoid, becoming yellow brown to medium brown in Melzer’s reagent (O1/2; P0/1/2; D2/3); yellow in KOH. Basidia 19-32 × 5-7 µm, with av. Q 3.8-4.6 µm, cylindrical to clavate, hyaline, 4-spored. Cheilocystidium width near apex holotype 5% to 95% percentile range 4.5-6.8 µm, with median 5.8 µm and av. 5.7 µm with S.D. 0.85 µm; across seven collections median 4.4-6.3 µm and av. 4.5-6.3 µm; examining approx. 20 selected cheilocystidia of each of the seven collections yields a range for the avs of 29-43 × 4.5-6.3 × 3.9-5.1 × 4.8-6.8 µm and 33 × 5.7 × 4.3 × 5.6 µm av. for the holotype. Cheilocystidium av. ratios A/M: 1.04-1.48, A/B: 0.84-1.31, B/M: 1.20-1.36, irregular but mainly cylindrical, often ventricose, often clavate, occasionally clavate-lageniform or clavate-ventricose or gently clavate, rarely capitate stipitate or clavate stipitate, often with one or two septa, occasionally with apical wall thickening. Pleurocystidia absent. Caulocystidia similar to cheilocystidia but larger, up to 100 μm. Pileipellis an ixocutis, epicutis up to 100 µm thick, with gelatinized, hyphae up to 7 µm wide, often encrusted; subcutis pale yellow; and the trama below the cutis made up of ellipsoid or thickly sausage-shaped, often cylindrical cells up to 13 µm wide. Clamp connections present throughout the basidiome.

Habitat and distribution.

Where only one possible associate was recorded, that associate has always been Quercus ( Fagaceae ). We have additional records where Pinus , Abies and Fagus were recorded as possible associates, but in each of these cases a number of possible associates were mentioned by the collector. We are only aware of five collections other than that from Mexico. These are all from the eastern half of the United States: Ohio, Pennsylvania and Tennessee.

Additional material examined.

Mexico. Tlaxcala: Municipality of Huamantla, La Malinche National Park , Cañada Grande, east side of La Malintzi volcano, approx. 19.1999°N, 97.9729°W, alt. approx. 3000 m, on soil in montane, temperate woodland under Abies sp. and Pinus sp., 25 Jul 1990, H. Cuevas HC1155 (TLXM HC1155, HJB16793 ) . USA. Ohio: Shaker Parklands, Doan Brook Gorge , approx. 41.495°N, 81.5953°W, alt. approx. 275 m, on grassy soil under Fagus sp. and Quercus sp., 26 Sep 2011, D. Bartholow SPFS-2011-63 ( HJB17796 ) . Pennsylvania: Fort Washington Park, Parking Lot 5, approx. 40.1208°N, 75.2232°W, alt. approx. 80 m, on soil in mixed woodland under Quercus sp., 23 Oct 2018, T. Deluce ( HJB18418 ) . Tennessee: Gatlinburg, Great Smoky Mountains National Park, Indian Gap , approx. 35.6108°N, 83.4386°W, alt. approx. 1650 m, 29 Jul 1941, L.R. Hesler LRH13890 (holotype of Hebeloma perangustisporium TENN-F-013890, HJB1000450) . Blount, Townsend , Great Smoky Mountains National Park, Cades Cove, approx. 35.6019°N, 83.8113°W, alt. approx. 550 m, 23 Aug 1959, L.R. Hesler LRH23364 (holotype of Hebeloma angustisporium TENN-F-023364, HJB1000314) .

Remarks.

The small weakly ornamented basidiospores together with the short irregular cheilocystidia, often cylindrical but also both ventricose and clavate, suggest Hebeloma sect. Naviculospora , which is supported by molecular data. Within this section H. subaustrale is differentiated from other Northern American species of this section by the average basidiospore length (a maximum of 10 µm), and average spore Q greater than 1.7, together with the cheilocystidia that have a maximum average A/B ratio of 1.5 and a minimum average B/M ratio of 1.2.

We were not able to generate any sequence data from the type of H. subaustrale . However, our morphological study of the type, and of a number of other species within H. sect. Naviculospora , leaves us in no doubt that this is a conspecific of both H. angustisporium and H. perangustisporium . For these latter two species types we have good morphological and molecular data. Table 1 shows a comparison of the most important taxonomic parameters for the holotypes of these three species. The spore size and the average cheilocystidium shape, despite their irregularity, are key to differentiating species within this section. The Mexican collection corresponded well with this type material and other recent collections from the USA.

Hebeloma subaustrale formed a reasonably well supported clade in the ITS analysis (Fig. 5B ), thus it is expected to be identifiable by its barcode. Although the maximum intraspecific distance of the sequences in the analysis is only 0.14%, the minimum distance to other species of the section is 0.7%. At this time (4 Feb 2022), there is no multi-sequence UNITE SH that represents the species; the published sequence of the holotype of H. angustisporium (NR_119890 = HQ179674) formed a singleton SH at the 99% level and the respective SH at the next level included several species.

Figures

Figure 5. ML topologies with branch support obtained through 1000 replicates of SH-like approximate likelihood ratio tests and ultrafast bootstrap annotated SH-aLRT / ufb at the branches for ≥ 85 % SH-aLRT and ≥ 95 % for ufb support. Collections indicated with * are types; clade names indicated by * include type sequences. Collections in red refer to Mexican material A concatenated ITS, MCM 7 and RPB 2 sequences of Hebeloma sect. Theobromina, rooted with H. sinapizans (H. sect. Sinapizantia) B ITS sequences of H. sect. Naviculospora, rooted with H. islandicum (H. sect. Naviculospora).

Figure 13. Hebeloma subaustrale A basidiospores and B spore ornamentation of holotype FLAS-F- 19345 x 1600 C spores of SPFS- 2011 - 63 (HJB 17796) in Melzer's reagent x 1600 D spores and cheilocystidia of holotype x 1000 E cheilocystidia of isotype TENN-F- 021177 x 1000 F cheilocystidia of holotype x 1000 G caulocystidia of isotype x 1000 H cutis of SPFS- 2011 - 63 x 125. All in KOH, except C. I basidiomata of collection SPFS- 2011 - 63. Scale bars: 5 µm (A-G); 50 µm (H). Photos A-G H. J. Beker H D. Bartholow.