Hydnum albomagnum Banker, Bulletin of the Torrey Botanical Club 28(4): 207 (1901)

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 albomagnum Banker, Bulletin of the Torrey Botanical Club 28(4): 207 (1901) Figs 3E, F, 6C

= Dentinum albomagnum (Banker) Pouzar, Ceská Mykologie 10 (2): 76 (1956)

Type.

UNITED STATES. Alabama: Lee County, Auburn, Dec 1896, F.S. Earle (holotype: NY 776138). Epitype. UNITED STATES. Tennessee: Big South Fork National River & Recreation Area, Bandy Creek area (36.4920; -84.6950), solitary on soil with Quercus , Pinus , 450 m, 23 Sep 2017, RAS231 (TENN 073062, epitype here designated).

Description.

Pileus 60-110 mm wide, irregularly round, irregularly convex to plano-convex or uplifted; surface dull, glabrous with adhering debris, uneven and sometimes pitted in places, cream white (4A4) with patches of cottony white, becoming light tan in age (10 YR 6/4); margin thin, wavy to slightly lobed, incurved when young then raised in age. Spines 1-6 mm long, brittle in mass, adnate to subdecurrent, white to cream white (4A3-5A3). Stipe 20-40 × 13-20 mm thick, central or eccentric, clavate, occasionally split in two towards the apex; surface smooth, concolorous with spines, if bruising then only very slightly an hour or more after handling ( “Yellow-Ocher” to “Ochraceous-Tawny”). Context fleshy, white, unchanging when cut. Odor mild or slightly acidic at first, then pleasantly fruity like apricots when stored in foil. Taste mild.

Basidiospores 5.5 –6.2– 7 μm × 3 –3.8– 5 μm, Q=1.24 –1.66– 2.07(2.17) (n=45/3), ellipsoid to broadly ellipsoid, smooth, thin-walled, hyaline in KOH. Basidia 38-46 × 5-6 μm with 4-5(6) sterigmata. Pileipellis a tightly interwoven cutis, hyphae smooth, cylindrical, thin-walled, mostly 2.5-5 μm wide. Clamp connections present.

Distribution.

Eastern U.S. - Massachusetts, North Carolina, Tennessee (epitype), and Alabama (holotype).

Ecology.

In hardwood and mixed woods with Quercus , Pinus . September to December.

Other specimens examined.

UNITED STATES. Massachusetts: Worcester County, Rutland State Park, gregarious under litter layer along edge of road with Quercus , Pinus strobus , 260 m, 1 Nov 2003, P.B. Matheny PBM2512 (TENN 066858). North Carolina: Buncombe County, Black Mountain YMCA Blue Ridge Assembly, Wolfpit Loop, in leaf litter in broadleaf woods with Quercus , Acer , 900 m, 24 Sep 2015, B. Moerk NAMA 2015-050 (F C0305359F). Tennessee: Knox County, New Hopewell, on soil in mixed woods, 300 m, 2 Dec 1951, L.R. Hesler (TENN 020243).

Discussion.

The original description of Hydnum albomagnum by Banker (1901) was based solely on dried material. As mentioned in the protologue, this species has a shorter stipe and overall stouter appearance than other Hydnum . In addition, mature basidiomes are much larger than other whitish small-spored species. Hydnum albomagnum also has more strongly ellipsoid spores (Q values averaging 1.66) than other species. Historically, H. albomagnum has been less frequently collected than other pale species of Hydnum , perhaps because the basidiomes are often buried underneath layers of needle and leaf litter and thus overlooked. As basidiomes emerge from the ground, leaf litter remains stuck to the matt glabrous surface of the pileus, masking its appearance. This characteristic, along with the creamy white coloration, large basidiome size, and small ellipsoid spores, makes this one of the easier Hydnum species to identify. DNA sequencing of the type specimen of H. albomagnum was not successful; however, all modern collections reported under this species name have identical ITS sequences and match the morphology of the original species description. An epitype is chosen from Tennessee material, closest to the location of the holotype from Alabama.

Collections that are likely H. alboaurantiacum (TENN 041525) and H. vagabundum (TENN 003140) have been misidentified as H. albomagnum , perhaps due to the larger white appearance of those specimens. However, those collections differ from H. albomagnum in spore dimensions and lack litter debris on the pileus, which persists even after drying in H. albomagnum .