Hemiaustroboletus, a new genus in the subfamily Austroboletoideae (Boletaceae, Boletales) Author Ayala-Vasquez, Olivia https://orcid.org/0000-0002-8970-9571 Tecnologico Nacional de Mexico, Instituto Tecnologico de Ciudad Victoria, Blvd. Emilio Portes Gil # 1301 Pte., Ciudad Victoria, Tamaulipas, CP 87010, Mexico Author Garcia-Jimenez, Jesus https://orcid.org/0000-0001-9290-1460 Tecnologico Nacional de Mexico, Instituto Tecnologico de Ciudad Victoria, Blvd. Emilio Portes Gil # 1301 Pte., Ciudad Victoria, Tamaulipas, CP 87010, Mexico Author Aguirre-Acosta, Elvira https://orcid.org/0000-0003-1360-7859 Instituto de Biologia, Universidad Nacional Autonoma de Mexico, Circuito exterior s / n Ciudad Universitaria, Ciudad de Mexico, CP 04510, Mexico Author Castro-Rivera, Rigoberto https://orcid.org/0000-0002-9083-1363 CIBA, Instituto Politecnico Nacional, Tlaxcala, CP 90700, Mexico Author Angeles-Argaiz, Rodolfo Enrique https://orcid.org/0000-0002-1225-2227 Instituto de Biologia, Universidad Nacional Autonoma de Mexico, Circuito exterior s / n Ciudad Universitaria, Ciudad de Mexico, CP 04510, Mexico Author Saldivar, Angel Emmanuel https://orcid.org/0000-0002-4503-3186 Departamento de Botanica y Zoologia, Universidad de Guadalajara, Zapopan, Jalisco, CP 45101, Mexico Author Garibay-Orijel, Roberto https://orcid.org/0000-0002-6977-7550 Instituto de Biologia, Universidad Nacional Autonoma de Mexico, Circuito exterior s / n Ciudad Universitaria, Ciudad de Mexico, CP 04510, Mexico rgaribay@ib.unam.mx text MycoKeys 2022 2022-03-30 88 55 78 http://dx.doi.org/10.3897/mycokeys.88.73951 journal article http://dx.doi.org/10.3897/mycokeys.88.73951 1314-4049-88-55 05D8DD51FFB350529DC32FC1ACA6F148 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) x 4-5 (-7) µm , slightly verrucose to cracked, fusoid to cylindrical; pleurocystidia ventricose-rostrate to fusoid, cheilocystidia sphaeropedunculate. 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 ). Holotype. Mexico. Oaxaca State, Santa Catarina Ixtepeji Municipality, La Cumbre Town, Pena Prieta site, 17°11'11.34"N , 96°38'00"W (DMS), 2800 m alt., 19 July 2017, Ayala-Vasquez (MEXU-30051; isotype ITCV-AV868). Figure 4. Hemiaustroboletus vinaceobrunneus (AV845- ITCV, MEXU-30052 Holotype) A basidiospores B basidia C pleurocystidia D cheilocystidia E pileipellis F caulocystidia. Scale bars: 10 µm ( A-F ). Etymology. The name refers to the colour of the pileus, from the Latin " vinosus " vinaceous when young and " brunneus " brown when mature. Figure 5. Basidiospore ornamentation of Hemiaustroboletus revealed by SEM A, C Hemiaustroboletus vinaceus (AV868- ITCV, MEXU-30051, Holotype) B, D Hemiaustroboletus vinaceobrunneus (AV1168- ITCV, MEXU-30053 Isotype). 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 x 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) x 4-5 (-7) µm , X = 14.04 x 4.96 µm , std = 3.46 x 0.99 µm , (n = 30, Q = (2.2) 2.4-2.5 (2.8), (holotype); (10-) 11-15 (-21) x 4.5-7 (-8) µm , X = 13.78 x 6.07 µm , std = 3.74 x 1.3 µm , Q = (2.2) 2.4-2.6 (2.8) (paratype MEXU-30052); (10-) 11-15 (-17) x (4-) 4.5-5.5 (-6) µm , X = 13.15 x 4 µm , std = 2.62 x 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) x 9-11 (-12) µm , clavate, hyaline in KOH, pale yellow in Melzer's reagent, with granular content, tetrasporic. Pleurocystidia 31-45 x 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) x 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) x 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) x 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 x 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-Vasquez (MEXU-30052; ITCV-AV845); Cabeza de Vaca site, 17°11'10"N , 96°38'28"W (DMS), 3038 m alt., 18 July 2017 , Ayala-Vasquez (ITCV-AV1121), Cabeza de Vaca site, 15 August 2018 , Ayala-Vasquez (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) x 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) x 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.