Hemiaustroboletus vinaceobrunneus Ayala-Vasquez , Garcia-Jimenez & Garibay-Orijel, 2022

Ayala-Vasquez, Olivia, Garcia-Jimenez, Jesus, Aguirre-Acosta, Elvira, Castro-Rivera, Rigoberto, Angeles-Argaiz, Rodolfo Enrique, Saldivar, Angel Emmanuel & Garibay-Orijel, Roberto, 2022, Hemiaustroboletus, a new genus in the subfamily Austroboletoideae (Boletaceae, Boletales), MycoKeys 88, pp. 55-78 : 55

Hemiaustroboletus vinaceobrunneus Ayala-Vasquez, Garcia-Jimenez & Garibay-Orijel sp. nov.

Figs 3 , 4 , 5B, D

Diagnosis.

Pileus vinaceous to brown, pores whitish to pinkish at maturity, vinaceous context; longitudinally fribrillose stipe; basidiospores (10) 11-17 (-21) × 4-5 (-7) µm, slightly verrucose to cracked, fusoid to cylindrical; pleurocystidia ventricose-rostrate to fusoid, cheilocystidia sphaeropedunculate.

Holotype.

Mexico. Oaxaca State, Santa Catarina Ixtepeji Municipality, La Cumbre Town, Peña Prieta site, 17°11'11.34"N, 96°38'00"W (DMS), 2800 m alt., 19 July 2017, Ayala-Vásquez (MEXU-30051; isotype ITCV-AV868).

Etymology.

The name refers to the colour of the pileus, from the Latin " vinosus " vinaceous when young and " brunneus " brown when mature.

Description.

Basidiomata stipitate-pileate. Pileus 36-40 mm diameter, convex when young becoming plano-convex, reddish-vinaceous (13B6) when young, orange brown (7C8), reddish-brown (8D8-8E8) to dark brown (7F8) with some ruby tones (12E8) at maturity, dry surface, subtomentose, rivulose to areolate, whitish context, decurved margin. Hymenophore slightly depressed around the stipe to subadnate, pores 1-1.2 mm diameter, circular to subangular, whitish when young, pink to red-whitish (11A3-11A2) at maturity, tubes 6 mm length, of pores concolorous, unchanging when cut or touched, tubes detachable from the context. Context 4-8 mm thick, whitish, with some shades of pale red, vinaceous at the edge of the pileus and at the apex of the stipe at maturity. Stipe 45-65 × 8-10 mm, subclavate, reddish-vinaceous (13B6), orange-brown (7C8) to brown (7D8 -7E8) at the apex and part of the base, orange in the middle area (6B8) to orange-brown (6C8), rest of the base whitish; surface furfuraceous, longitudinally fibrillose. Whitish mycelium. Chemical reactions pileus negative in KOH, the context and the hymenophore slightly become pale violet (16A2) and the stipe becomes pale brown (6D4). When ammonium hydroxide (NH4OH) is applied, the pileus becomes brown-violet (11F8-11F7), the hymenophore and context pale orange (5A2) and the stipe pale violet (16A2).

Basidiospores 10-15 (-20) × 4-5 (-7) µm, X = 14.04 × 4.96 µm, std = 3.46 × 0.99 µm, (n = 30, Q = (2.2) 2.4-2.5 (2.8), (holotype); (10-) 11-15 (-21) × 4.5-7 (-8) µm, X = 13.78 × 6.07 µm, std = 3.74 × 1.3 µm, Q = (2.2) 2.4-2.6 (2.8) (paratype MEXU-30052); (10-) 11-15 (-17) × (4-) 4.5-5.5 (-6) µm, X = 13.15 × 4 µm, std = 2.62 × 0.64 µm, Q = (2.2) 2.6-2.9 (3) µm, (paratype ITCV-AV1121), cylindrical to subfusoid, slightly verrucose to cracked, brown-orange in KOH, inamyloid in Melzer’s reagent. Basidia 30-33 (-49) × 9-11 (-12) µm, clavate, hyaline in KOH, pale yellow in Melzer’s reagent, with granular content, tetrasporic. Pleurocystidia 31-45 × 8-11 µm, ventricose to fusoid, some mammillate, hyaline in KOH, yellowish in Melzer’s reagent, thick walled (1-1.5 µm). Cheilocystidia 42-70 (-86) × 9-15 (-17) µm, clavate with septa (1-2 µm thick), sphaeropedunculate, some mammillate, hyaline in KOH, yellowish in Melzer’s reagent, thick-walled (1-1.5 µm). Hymenophoral trama boletoid; hyphae cylindrical 3-15 µm diameter, with gelatinous wall some with smooth walls, hyaline to yellowish in KOH and Melzer’s reagent. Pileipellis a trichoderm with terminal cells (22-) 35-75 (-105) × 8-14 (-21) µm, cylindrical to subclavate, hyaline in KOH, yellowish in Melzer’s reagent, embedded in a gelatinous substance and with visible contents in Melzer’s reagent, thick-walled (1-1.5 µm). Caulocystidia 20-64 (-140) × 6-14 (-16) µm, fusoid, cylindrical to sphaeropedunculate with one to two septa, hyaline to yellowish KOH with visible contents visible in Melzer’s reagent. Caulobasidia 25-30 × 7-8 µm tetrasporic, concolorous with the caulocystidia. Clamp connections absent.

Habit and habitat.

Solitary, in Abies guatemalensis , Pinus pseudostrobus and Quercus laurina mixed forest, putatively associated with Quercus laurina , from 2800 to 3000 m alt.

Known distribution.

Currently only known from Oaxaca State, southeast Mexico.

Additional materials examined.

Mexico, Oaxaca State, Santa Catarina Ixtepeji Municipality, La Cumbre Town, East of cottage site, 17°11'30"N, 96°38'18"W (DMS), 2903 m alt., 18 July 2017, Ayala-Vásquez (MEXU-30052; ITCV-AV845); Cabeza de Vaca site, 17°11'10"N, 96°38'28"W (DMS), 3038 m alt., 18 July 2017, Ayala-Vásquez (ITCV-AV1121), Cabeza de Vaca site, 15 August 2018, Ayala-Vásquez (MEXU-30053; ITCV-AV1168) .

Remarks.

Hemiaustroboletus vinaceobrunneus differs from H. vinaceus by its context with vinaceous tones especially at maturity and a whitish-pink to pale red hymenophore; the stipe is orange-brown; basidiospores are 10-15 (-20) × 4-5 (-7) µm, finely verrucose to cracked, lodged to sphaeropedunculate cheilocystidia, caulocystidia fusoid, cylindrical to sphaeropedunculate with a septum. In contrast, H. vinaceus has a whitish context with slight yellowish-brown tones near the epicutis, has shorter basidiospores (9-) 10-14.4 (-16) × 4-5(-8) µm, cylindrical to clavate queilocystidia and caulocystidia fusoid or clavate. In the field, the former can be mistaken for Gyroporus purpurinus because of the colours and size of the basidiomata, but G. purpurinus has a hollow stipe ( Davoodian and Halling 2013), while H. vinaceobrunneus has a compact context.

Figures

Figure 3. Hemiaustroboletus vinaceobrunneus A, C basidiomata (MEXU- 30052 Holotype) B, D pileus (MEXU- 30053, MEXU- 30051, Isotype) E hymenophore (MEXU- 30052 Holotype) F, G context (MEXU- 30052 Holotype). Scale bar: 10 mm (A-G).

Figure 4. Hemiaustroboletus vinaceobrunneus (AV 845 - ITCV, MEXU- 30052 Holotype) A basidiospores B basidia C pleurocystidia D cheilocystidia E pileipellis F caulocystidia. Scale bars: 10 µm (A-F).

Figure 5. Basidiospore ornamentation of Hemiaustroboletus revealed by SEM A, C Hemiaustroboletus vinaceus (AV 868 - ITCV, MEXU- 30051, Holotype) B, D Hemiaustroboletus vinaceobrunneus (AV 1168 - ITCV, MEXU- 30053 Isotype).