Hydnum albidum Peck, Bulletin of the New York State Museum 1(2): 10 (1887)

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 albidum Peck, Bulletin of the New York State Museum 1(2): 10 (1887) Figs 3A, B, 6A

= Hydnum repandum var. albidum (Peck) Bres., Iconographia Mycologica 21: 1045 (1932)

= Dentinum albidum (Peck) Snell, Mycologia 37: 51 (1945)

Hydnum = Hydnum repandum f. albidum (Peck) Nikol., Flora Plantarum Cryptogamarum URSS. Fungi. Familia Hydnaceae 6(2): 306 (1961)

Type.

UNITED STATES. New York: Rensselaer County, Sandlake, ground in thin woods, Jul ca. 1886, C.H. Peck (holotype: NYS-F-134). Epitype. UNITED STATES. New York: Cortland County, Kennedy State Forest, Scutt Road (42.4685; -76.1656), on humus in forest with Quercus rubra , Fagus , Acer , 550 m, 30 Jul 2014, T.J. Baroni 10640TJB (CORT 012029, epitype here designated).

Description.

Pileus 15-50 mm wide, round to reniform, convex to plano-convex or uplifted, disc sometimes shallowly depressed; surface glabrous, sometimes irregularly bumpy or mottled in appearance, bright white becoming cream or cream-peach (10YR 8/4), no reaction to KOH; margin entire and incurved when young, undulating in age. Spines 1-6 mm long, easily rubbing off, subdecurrent to decurrent, white to cream white (10YR 8/3). Stipe 15-45 × 5-15 mm, central or eccentric, equal to slightly enlarged or bulbous at the base, then tapering into ground, concolorous with the pileus, staining orange-ochre (5A4-5B7 or "Yellow Ochre"). Basal mycelium white when present. Context white to pale cream, staining slowly orange (5A6) after five mins. Odor mild at first, then pleasantly fruity like apricots when stored in foil. Taste mild, pleasant, or occasionally peppery.

Basidiospores 4.5 –5.2– 6 μm × 3 –4– 4.5(5) μm, Q=(1.05)1.07 –1.33– 1.58(1.74) (n=72/5), subglobose to broadly ellipsoid, smooth, thin-walled, hyaline in KOH. Basidia 28-36(40) × 6-7(8) μm with 5-6(7) sterigmata. Pileipellis an interwoven cutis, hyphae smooth, cylindrical, thin-walled, mostly 3-6 μm wide. Clamp connections present.

Distribution.

Eastern Canada and U.S. and central Mexico - Nova Scotia, Vermont, New York (type), Tennessee, North Carolina. Also Veracruz, Mexico (GenBank KC152123).

Ecology.

In hardwood and mixed woods with Betula , Quercus , Fagus , Tsuga , Pinus , Abies . June to early September.

Other specimens examined.

CANADA. Nova Scotia: Victoria County, Cape North, Grey Glen Brook, Farm lot, with Abies , Betula , 80 m, 8 Sep 1973, R.H. Petersen TFB38198 (TENN 038198). UNITED STATES. New York: Cortland Co., Kennedy Forest, Scutt Hill Road, on humus under Quercus , Fagus , Acer , 550 m, 10 Aug 2003, T.J. Baroni 9623TJB (CORT 014489). North Carolina: Great Smoky Mountains National Park, Heintooga Round Bottom Road, top of road on embankment with Betula , Picea , 1525 m, 17 Aug 2017, R.A. Swenie RAS204 (TENN 071752). Great Smoky Mountains National Park, Heintooga Round Bottom Rd., on embankment with Betula , Quercus , Tsuga , 1525 m, 17 Aug 2017, R.A. Swenie RAS210 (TENN 073173). Tennessee: Great Smoky Mountains National Park, Ogle Place Nature Trail, near stream in soil among leaf litter with Tsuga , Betula , 670 m, 5 Jun 2016, R.A. Swenie RAS058 (TENN 072000). Great Smoky Mountains National Park, Schoolhouse Gap Trail, on embankment with Quercus , Pinus , Betula , 550 m, 8 Jul 2017, R.A. Swenie RAS158 (TENN 073041). Vermont: Windham County, Stratton Mountain Resort area, 650 m, 28 Jul 2017, T.J. Baroni 10788TJB (CORT 014475).

Discussion.

Hydnum albidum was originally described from New York by Peck (1887) and produces small white to cream-colored basidiomes with small subglobose to broadly elliptic basidiospores. In the protologue Peck distinguishes H. albidum from H. repandum by the smaller basidiomes and spores, as well as white coloration. In a later description Peck (1897) added that H. albidum is an edible but uncommon species "uniformly colored in all its parts". Of the two small white species of Hydnum that occur in eastern North America (Fig. 3A-D), both H. albidum and H. alboaurantiacum have similarly small subglobose basdiospores (Fig. 6 A–B). However, H. alboaurantiacum quickly stains bright orange within minutes wherever handled, while H. albidum stains much less vividly brown-orange, sometimes only hours after handling. In addition, H. alboaurantiacum is only known from the southeastern US. While we were unable to successfully sequence DNA from the holotype of H. albidum , several collections from the region of the type locality are consistent with the morphology of the holotype of H. albidum , and one of these is designated as an epitype.

In addition to the holotype, there are several other historical collections made by Peck to which he applied the name H. albidum . Based on basidiospore measurements alone, it is clear three of the eight collections have much larger spores than H. albidum . We successfully sequenced partial ITS from two of those three collections, which matched modern specimens from Texas, New York, and Honduras belonging to a species more closely related to H. repandum (see discussion of H. vagabundum ).

Hydnum repandum var. album ( Quél.) Rea is a European variety, the name of which has been widely applied in North America ( Coker and Beers 1951, Smith et al. 1981, Harrison and Grund 1987, Roody 2003). The description of H. repandum var. album by Roody (2003) appears to refer to H. subtilior , while displaying a photo of what is perhaps H. albidum . However, the spores of H. albidum are smaller than the 7-8.5 × 5.5-7 μm listed by Roody (2003), Harrison and Grund (1987), Smith et al. (1981), and Coker and Beers (1951). Thus, the American concept of H. repandum var. album is best interpreted as H. subtilior , described below.