Aureoboletus pseudoauriporus J.A. Bolin, A.R. Bessette, A.E. Bessette, L.V. Kudzma, A. Farid & J.L. Frank sp. nov.
MycoBank number: MB 840856; Index Fungorum number: IF 840856; Facesoffungi number: FoF 10467;
Pileus 5–8.5 cm broad, convex at first, remaining so well into maturity; surface glabrous, color variable, pinkish to pinkish red or pinkish tan, usually losing pinkish tones when mature, unchanging when bruised, tastes acidic; margin incurved, even or narrowly sterile; staining pale yellow-orange then fading to light brown with the application of KOH, pale blue-green fading quickly or slowly with NH4OH, slowly staining light greenish gray or negative with FeSO4. Context white, unchanging or faintly and slowly turning pink or light yellow near the hymenium; staining yellow-orange with KOH, slowly light greenish gray or negative with NH4OH, and light blue-green or negative with FeSO4; odor and taste not distinctive. Hymenophore tubulose, bright yellow when young, becoming darker yellow and then dingy yellow with age, not staining when bruised or cut; pores rounded, 1–2 per mm; tubes 4–12 mm deep. Stipe 4–6 cm long, 8–12 mm at the apex, 1–1.4 cm thick at the base, typically equal or slightly enlarged downward, sometimes with a pinched base; surface typically dry but viscid when wet, typically longitudinally striate for one-third or more of its length, whitish, sometimes with pale pink tones, not staining when bruised; context white, firm and woody toward the base, often staining faintly pinkish; with white basal mycelium.
Basidiospores light to medium brown in fresh deposit, (14–)15–17(–18) × 5–6.5 µm, n = 30, Q = 2.79, elliptical in face view, inequilateral in profile, thick-walled, smooth, lacking an apical pore, yellow-brown in KOH or Melzer’s. Basidia 25–38 × 8–13 µm, clavate, 2-sterigmate, hyaline in KOH or Melzer’s. Basidioles 12–23 × 6.5–8 µm, clavate, thin-walled, hyaline in KOH or Melzer’s. Hymenial cystidia 30–50 × 10–15 µm, cylindrical, sometimes with a capitate to capitulate apex. Hymenophoral trama boletoid, with lateral elements, 4–12 µm wide, moderately divergent, hyaline in KOH or Melzer’s. Pileipellis an ixotrichoderm, terminal elements 7–22 µm wide, highly variable, thin-walled, smooth, hyaline in KOH, with golden yellow contents in Melzer’s. Pileus trama hyphae loosely interwoven, highly variable, 6–32 µm wide, smooth, thin-walled, hyaline in KOH or Melzer’s. Stipitipellis mostly parallel, slightly interwoven, 4–12 µm wide, hyaline in KOH or Melzer’s, with fascicles of clavate or fusiform caulocystidia. Caulocystidia of two types; clavate, 24–42 × 12–22 µm, with yellowish contents in KOH, thin-walled, smooth; fusiform 32–39 × 8–12 µm, hyaline in KOH, thin-walled, smooth. Stipe trama interwoven, 6–13 µm wide, hyaline in KOH or Melzer’s, thin-walled, smooth. Clamp connections absent.
Material examined: USA, Florida, Hillsborough County, Brandon, S of Camden Visconti entrance pond, adjacent to canal, 27°55’27.9″N 82°20’22.9″W, 5 Oct 2016, A. Farid 501 (USF 288287); Tampa, Violet Cury Nature Preserve, 4 Jun 2017, A. Farid 592 (USF 301502); Tampa, Trout Creek Nature Preserve, Xeric hammock beneath Quercus geminata, 3 May 2019, A. Farid 919 (USF 301507); Lake County, Lake Louisa State Park, Clermont, 24 Oct 2019, J.A. Bolin 448 (USF 301492); Miami-Dade County, Everglades National Park, 5 Jul 2019, A. Farid 959 with A.R. Franck and R.E. O’Donovan (EVER 144770); Palm Beach County, Frenchman’s Forest natural Area, 28 May 2018, J.A. Bolin 167 (USF 301497); Hypoluxo Scrub Natural Area, Lantana, 21 Nov 2017, J.A. Bolin 80 (USF 301487); ibid., 70 Sep 2019, 7 Sep 2019, J.A. Bolin 106 (USF 301489); ibid., 6 Nov 2017, J.A. Bolin 130, (USF 301493); Jupiter, Abacoa Natural Area, 1 Mar 2019, J.A. Bolin 320 (holotype USF 301510); ibid., 13 Aug 2019, J.A. Bolin 418 (USF 301483).
Distribution: Solitary or scattered in sandy soil with oak in a scrubby flatwood community; known from central Florida, distribution limits yet to be determined.
Sequence data: ITS: MW675726.1 (ITS1/ITS4); LSU: MW662585.1 (LROR/LR5); EF1a: MW737489.1 (EF1-BF1/EF1-B-R); RPB1: MW737508.1 (RPB1-B-F/RPB1-B-R); RPB2: MW737468.1 (RPB2-B-F1/RPB2-B-R)
Notes: This species is a part of a cryptic species complex. It greatly resembles Aureoboletus auriporus (Peck) Pouzar, and its distribution limits are yet to be established. Aureoboletus auriporus differs from A. pseudoauriporus by the lack of longitudinal striations on the stipe. The pileus of A. auriporus is reported to turn red with the application of NH4OH (Baroni 2017). The spore size of A. auriporus was not originally reported in the protologue, though Peck (1889) later provided an expanded description and reported the spores as 7.5–10 × 4–5 µm. Both (1998) studied the type specimen, obtaining a spore size of 9.8–15.5 × 3.96–5.75 µm, with a mean dimension of 13.15 × 4.73 µm, Q = 2.12–3.39, Qm = 2.75. Both (1998) also provided a description based on collections primarily from New York and Rhode Island, but also included a specimen from Tennessee, and did not include the type specimen. The spores reported were slightly larger than the type, at 11.0–16.05 × 4.4–6.38 µm, mean dimension 14.36 × 5.19 µm, and the spore quotient was similar, at Q = 2.2 – 3.19, Qm = 2.78. The spores of A. pseudoauriporus are somewhat larger, at (14–)15–17(–18) × 5–6.5 µm, × = 16.45 × 5.92 µm, and the spore quotient is nearly identical, at Q = 2.79.
Aureoboletus viridiflavus Coker & Beers ex Klofac is a similar species, and has been treated as a synonym of A. auriporus in the past (Singer 1947, Both 1998), which differs primarily by the pileus colors, which was described as “olivaceous gold with reddish areas”, the pileus when young tomentose-felted, less viscid, a lack of distinctly projecting margin, the hymenophore longer, to 17.5 mm (4–12 mm in A. pseudoauriporus), and the stipe, which bruises “brick red” and is not viscid (white, sometimes with pale pink tones, and not bruising in A. pseudoauriporus). The spore size is similar to A. auriporus, reported as 11.5–15 (–16.6) × 4–5 µm in the protologue. Aureoboletus pseudoauriporus has somewhat longer and wider spores, measuring (14–)15–17(–18) × 5–6.5 µm. Aureoboletus subacidus (Murrill ex Singer) Pouzar is a somewhat similar species that shares reddish tones in the pileus, citrine yellow tubes, a whitish stipe, occurs in Florida, and is associated with Quercus spp. It can readily be distinguished from A. pseudoauriporus by the presence of the floccose yellow velar remnants left on the upper portion of the stipe, the scrobiculate pileus, and the yellow pileal context (Singer 1947).
So far, A. pseudoauriporus is the only species in the complex known from Florida. Although A. pseudoauriporus has been observed in southeastern Georgia (USA) by the authors, no collections were made. Aureoboletus innixus (Frost) Halling, A. R. Bessette & A. E. Bessette is similar but it has a dry, somewhat velutinous, dull reddish-brown pileus, and lacks longitudinal striations on its stipe. Aureoboletus roxanae (Frost) Klofac has whitish pores when young which eventually become pale yellow, and a yellow to pale orange-yellow stipe with a distinct dull orange zone at the apex.