Hydnum aerostatisporum Buyck, Lewis & V. Hofstetter, Crypt. Mycologie, 38: 101-146 (2017)

Swenie, Rachel A., Baroni, Timothy J. & Matheny, P. Brandon, 2018, Six new species and reports of Hydnum (Cantharellales) from eastern North America, MycoKeys 42, pp. 35-72 : 35

Hydnum aerostatisporum Buyck, Lewis & V. Hofstetter, Crypt. Mycologie, 38: 101-146 (2017) Figs 3E, F, 5H

= Hydnum subrufescens Niskanen & Liimat., Mycologia 110: in press (2018)

Type.

UNITED STATES. Texas: Polk County, Big Thicket Natural Preserve, Big Sandy Creek Unit, Beaver Slide Trail (30.6150; -94.6700), 4 Jul 2014, Buyck 14.156 (PC0142475).

Description.

Pileus (20)30-100 mm wide, irregularly round or sometimes reniform, convex to plano-convex, becoming funnel-shaped in age, sometimes with slit or umbilicus forming over stipe, surface dry, glabrous, subzonate when young, then cracking to coarsely scurfy in age, bright to medium brownish orange ("Xanthine Orange" to "Orange Rufous"), paler when young ( “Salmon-Orange”), often cracking in age to reveal lighter color of context ("Pale Pinkish Buff"); margin incurved and entire when young, then wavy, irregular or degraded in age, discoloring slightly darker after handling. Spines 1-9 mm long, close, mostly awl-shaped but occasionally spathulate, adnate to subdecurrent, buff to peach ("Light Buff" to "Pinkish Buff"). Stipe 25-80 × (3)7-25 mm, central or eccentric, equal or slight bulbous at base in younger specimens, smooth, often with white hazy or cottony patches overlaid on surface, cream white to pale orange in younger basidiomes, then darker tan orange with age, discoloring very slightly brownish orange when handled. Context cream to peach colored, firm, sometimes hollow with age, unchanging after 5 minutes when cut in half. Odor mild or sweet at first, then pleasantly fruity like apricots when stored in foil. Taste mild or weakly acrid.

Basidiospores 7 –8.1– 8.5 × 6 –7– 8 μm, Q=1.01 –1.15– 1.33 (n=38/3), mostly broadly ellipsoid, smooth, hyaline in KOH. Basidia 40-47 × 8-10 μm with (2)3-5 sterigmata. Pileipellis an interwoven cutis, hyphae smooth, cylindrical, thin-walled, mostly 4-6 μm wide. Clamp connections present.

Distribution.

Eastern U.S. - Illinois, Texas (type), North Carolina, Tennessee, Virginia, and Florida.

Ecology.

In hardwoods of Quercus , Carya , Ulmus or mixed woods including Betula , Picea , Tsuga . June to October.

Specimens examined.

UNITED STATES. Florida: Alachua County, Gainesville, University of Florida Natural Area Teaching Laboratory, 30 m, 9 Sept 2016, A. I. Zuniga AIZ-021 (FLAS 60406). Alachua County, Gainesville, Possum Creek Park, in deep woods with Carya and some Quercus , soil rich and not sandy, 55 m, 9 Oct 2015, M.E. Smith MES1432 (FLAS 59996). Illinois: Coles County, Fox Ridge State Park, 230 m, 28 Sep 1996, M. Kuo MK09289621. Dewitt County, Weldon Springs State Recreation Area, gregarious under Carya with Quercus alba , Quercus rubra , Ulmus nearby, 215 m, 18 Aug 2014, M. Kuo MK09181403. North Carolina: Great Smoky Mountains National Park, Heintooga Round Bottom Road, scattered on mossy bank with Picea , Betula , other hardwoods, 1580 m, 24 Jul 2016, R.A. Swenie RAS071 (TENN 073001). Great Smoky Mountains National Park, Heintooga Round Bottom Road, solitary on embankment with Picea , Betula , 1525 m, 17 Aug 2017, R.A. Swenie RAS211 (TENN 073174). Great Smoky Mountains National Park, Cataloochee, Big Fork Ridge Trail, 1100 m, 18 Jun 2005, E.B. Lickey TFB12514 (TENN 060681). McDowell County, near Little Switzerland, with Tsuga , ca. 1000 m, 19 Aug 2016, A. Funston RAS107 (TENN 073017). Tennessee: Great Smoky Mountains National Park, Cades Cove Road, 1 mile before Schoolhouse Gap Rd, 610 m, 31 Jul 2004, R.H. Petersen TFB12108 (TENN 060046). Great Smoky Mountains National Park, Tremont River Trail, solitary on slope in mossy area in mixed woods with Tsuga and hardwoods, 450 m, 4 Jul 2017, B. Teresi & K. Hucks RAS157 (TENN 073040). Texas: Polk County, Big Thicket National Preserve, Beaverslide Trail, on ground in mixed woods, 30 m, 12 Jun 2017, R.L. Pastorino RLP61217D (TENN 073547). Virginia: Shenandoah National Park, Hogback Mountain, 600 m, 9 Sept 2016, RAS121 (TENN 073024).

Discussion.

Hydnum aerostatisporum is a commonly encountered species in the eastern U.S. It has been found primarily in hardwoods and mixed woods including conifers at high and low elevations on both sandy and non-sandy soils. The vibrant medium to dark orange pileus transitions from smooth in young specimens to conspicuously cracked and scurfy in age, often becoming funnel-shaped, occasionally with a hole or umbilicus. The stipe frequently becomes darker tan-orange in age, which is unusual in other medium-sized orange-pileate species of Hydnum . Basidiomes, particularly older specimens, often have patches of hazy white on the stipe surface.

Hydnum aerostatisporum was recently re-described as a new species from Quebec - H. subrufescens ( Niskanen et al. 2018). The ITS sequence of the holotype of H. subrufescens differs from that of the holotype of the earlier described H. aerostatisporum by seven base pairs, but H. subrufescens does not form a well-supported monophyletic group in our phylogenetic analyses and recognition of H. subrufescens as a separate species would render H. aerostatisporum paraphyletic (Fig. 2). The morphology of both is consistent, including the similarly sized globose to subglobose spores. For these reasons, we consider H. subrufescens a taxonomic synonym of H. aerostatisporum .