Hemiaustroboletus vinaceus Ayala-Vasquez , Garcia-Jimenez & Saldivar, 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 vinaceus Ayala-Vasquez, Garcia-Jimenez & Saldivar sp. nov.

Figs 5A, C , 6 , 7

Diagnosis.

Pileus dark violet to dark brown, whitish context; hymenophore pink-purple to violet-brown; stipe surface tomentose to longitudinally fribrillose; basidiospores 9-13 × 4-5 µm, surface with cylindrical pits; pleurocystidia and cheilocystidia fusiform-ventricose to lanceolate.

Holotype.

Mexico, Jalisco State, Tequila Municipality, Tequila Volcano site, between 11 and 12 km on the road uphill to the antenna station, 20°48'35"N, 103°51'46"W (DMS), 2144 m alt., 18 August 2019, Á.E. Saldivar (IBUG-AES334).

Etymology.

The name refers to the colour of the pileus from the Latin " vinosus " vinaceous.

Description.

Pileus 35-70 mm in diameter, convex when young, becoming plano-convex with age, dark violet (16F6-16F4), violet-brown (11F5-11F8), orange-brown (5E7), with lighter shades of dark brown (6F5-6F8) lighter towards margin, whole edge, straight, dry surface, finely scamose, slightly areolate at the centre. Hymenophore adnate, slightly depressed, pores 0.5-2 mm in diameter, subangular to angular, pink-purple (14A4), lilac (14B4-14C4), magenta-grey (14C4-14D4), ruby-grey (12C4-12D4), colour unchanging when injured, tubes 7-10 mm, concolorous with the pores. Context 7-12 mm thick, solid, whitish, with slight yellowish-brown tones near the epicutis. Stipe 62-77 × 8-9 mm, central, cylindrical, with wider base, surface with longitudinal striations, whitish at the apex, yellowish-brown (5D5-5E5), orange-brown (5C5) shades in the middle, base with yellowish (5B6) to whitish shades; whitish context, unchanged when cut. Whitish basal mycelium. Odour pleasant. Taste slightly acidic. Chemical reactions: KOH reddish-brown in pileus, brown in hymenophore, slightly pinkish in context, yellowish-brown in stipe. NH4OH orange with violet tones on pileus, yellow in hymenophore, pale yellow in context, red-orange in stipe.

Basidiospores 9-13 (-14.5) × 4-5 (-8) µm, X = 12.14 × 5.2 µm, std = 2.08 × 1.36 µm, (n = 35), Q = (1.8) 2.1-2.2 (2.5) (holotype); (10-) 12-14 × 4-5 (-7) µm, X = 11.94 × 5.14 µm, std = 1.60 × 1.13 µm, (n = 35), Q = (2.2) 2.3-2.4 (2.5), (paratype MEXU-30103); (10-) 14-15 (-16) × (4-) 5-6 (-7) µm, X = 14.29 × 5.8 µm, std = 1.69 × 0.76 µm, (n = 40), Q = (2.2) 2.3-2.5 (2.6), (paratype colpos-CP5); subfusiform to cylindrical, slightly rough or dotted, apex rounded to subacute, with suprahilar depression, yellowish. Basidia 27-34 × 7-15.2 µm, claviform, bisporic, tetrasporic, with sterigma 2-4 × 0.5-1 µm, thin-walled, hyaline in KOH, yellow in Melzer’s reagent. Pleurocystidia 28-50 × 6.4-11 µm, fusoid-ventricose, slightly lanceolate, with content hyaline in KOH, yellow in Melzer’s reagent, with walls 0.5 μm thick. Cheilocystidia 25-61 × 6.4-11 µm, subclavate, hyaline in KOH, yellow in Melzer’s reagent, thin-walled. Hymenophoral trama divergent, with central and lateral hyphae tubular, 2-6 µm wide, hyaline in KOH, yellow in Melzer’s reagent, thin-walled; septa without clamp connections. Pileipellis a trichoderm with terminal cells 32-92 × 5-11 µm, cylindrical to subclaviform, hyaline in KOH, yellow in Melzer’s reagent, thin-walled. Caulocystidia 29-95 × 14-17 (-19) µm, subclaviform to claviform, thin-walled, with yellow visible contents in Melzer’s reagent, hyaline in KOH.

Habit and habitat.

Pinus - Quercus forests and Quercus forests, associated with Q. liebmanii and other Quercus spp.

Known distribution.

Currently only known from Neovolcanic Axis and Sierra Madre del Sur, Mexico.

Additional material examined.

Mexico, Jalisco State, Tequila Municipality, Tequila Volcano site, km 11-12 on the road uphill to the antenna station, 20°48'14"N, 103°51'37"W (DMS), 2144 m alt., 18 September 2019, A.E. Saldivar (IBUG-AE364); Oaxaca State, San Antonio de la Cal Municipality, Las Peñas site, 17°01'11"N, 96°40'33"W (DMS), 2160 m alt., 4 October 2014, Ayala-Vásquez (MEXU-30103; ITCV-AV524, duplicated ENCB); Michoacan State, Road Morelia, Ciudad Hidalgo Town, km 40, 21 July 1983, García-Jiménez (ITCV-3662), Mil Cumbres Town , 9 August 1969, R. Singer M8993 (F). Estado de México State, Ocuilan, San Juan Atzingo Town , mixed forest, 15 July 2021, mycoredes (Colpos- CP5) .

Remarks.

Hemiaustroboletus vinaceus differs from H. vinaceobrunneus due to its dark violet pileus, lilac to violet hymenophore, yellow stipe in the basal area and whitish apex. It has short, perforated basidiospores 9-13 (-14.4) × 4-5 (-8) µm, caulocystidia clavate to fusoid and pileipellis formed by a trichoderm with terminal cell cylindrical or subclavate, thin-walled. In contrast, H. vinaceobrunneus has a pileipellis formed by a trichoderm with encrustations. Hemiaustroboletus vinaceus is easily confused with Austroboletus gracilis sensu Wolfe (1979), because of its macroscopic characteristics and basidiospore ornamentation, but A. gracilis differs by pileus red-brown, brown-orange, having a total or partial reticulum on the stipe surface; longer basidiospores 10-19.5 × 4.5-9 µm, rugulose- punctate, elliptical to ovoid-elliptical. Austroboletus var. gracilis (Peck) Wolfe differs from H. vinaceus by pileus surface dry, finely velvety, when young, sometime rimose, reddish-brown, cinnamon or yellow-brown; stipe surface anastomosing lines, narrow reticulation overall or at least on the upper half; basidiospores 10-17 × 5-8 µm, narrowly ovoid to subelliptical. Austroboletus gracilis var. laevipes is distinguished by the smooth stipe, pileus yellow-ochraceous to yellow-brown, stipe subclavate, striate, finely pruinose, neither ribs nor reticulated surface, pale yellow or yellow-brown, basidiospores 11.2-14 × 5-8µm, oval-elliptical in face view, inequilateral in profile ( Bessette et al. 2000). Austroboletus gracilis var. pulcherripes Both & Bessette differs from H. vinaceus by a white hymenium when young, becoming pinkish to pale cocoa at maturity; stipe clavate, surface dry, coarsely reticulated on the upper two- thirds, reticulated, finely tomentose; basidiospores 13-19 × 5-8 µm, smooth to rugose-punctate, ovoid-elliptical, narrowly ovoid, inequilateral profile.

Figures

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).

Figure 6. Hemiaustroboletus vinaceus (AES 334 - IBUG, Holotype) A, B basidiomata C hymenophore D context E pileus surface. Scale bar: 10 mm (A-E).

Figure 7. Hemiaustroboletus vinaceus (AES 334 - IBUG, Holotype) A basidiospores B basidia C pleurocystidia D cheilocystidia E pileipellis F caulocystidia. Scale bars: 10 µm (A-F).