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Page number:1053 
Remarks (internal):Tuber oregonense differs from the other three species of the Gibbosum clade by its long, narrow spores common in one- to four-spored asci and its generally taller spore ornamentation. It is less widely distributed than the others, being recorded only from southwestern Washington and western Oregon. In addition to the molecular differences between the two the largest spores of T. oregonense are subfusoid with Q up to 2.9 and a reticulate ornamentation mostly 5-7(-8) µm tall. Tuber oregonense fruits primarily in autumn to early winter. T. gibbosum in contrast has only ellipsoid spores with Q no larger than 1.45 and a reticulum 3-5(-6) µm tall and fruits from autumn through winter to early summer. Both species are commercially harvested for culinary use. T. oregonense is the most commonly collected Tuber species in autumn in the Pacific Northwest (Trappe et al. 2009). It often occurs in great numbers in suitable habitats, but in forests the ascomata tend to be at the small end of its size range. The largest specimens have been found in Christmas tree farms or along golf course fairways.  
Description type:Original description 
Description:Tuber oregonense Trappe, Bonito & Rawlinson, sp. nov. Figs. 3B, F, J, N; 5E
MycoBank MB515123, Genbank FJ809874
Ascomata hypogeous, 0.5-5(-7.5) cm broad, the smaller specimens globose to subglobose and randomly furrowed (fig. 3B), the larger irregular, lobed and deeply furrowed. Peridium in youth white, soon developing red to reddish brown or orange brown patches; with age becoming orange-brown to reddish brown overall and often cracking, 0.2-0.4 mm thick, the surface roughened-glabrous to minutely pubescent, densely in the furrows and more scattered on the exposed lobes where the pubescence often collapses in age. Gleba solid, in youth the fertile tissue whitish and marbled with mostly narrow, white, hypha-stuffed veins that emerge here and there through the peridium to its surface; at maturity the fertile tissue light brown to brown from the color of the spores but the marbling veins remaining white. Odor and flavor mild in youth, soon becoming strong, pungent and complex, "truffly".
Spores ellipsoid to subfusoid with narrowed ends, light brownish golden, in one-spored asci excluding ornamentation 42.5-62.5 x 17.5-30 µm, Q = 1.55-2.5 (-2.9); in two-spored asci 32.5-50 x 15-25 µm, Q = 1.5-2.4; in three-spored asci 27.5-45 x 15-25 µm, Q = 1.5-2.0 (-2.45); in four-spored asci 25-38.5 x 13-28 µm, Q = 1.4-2.2(2.3); in five-spored asci 28-34 x 22-25 µm, Q = 1.3-1.4; spore walls 2-3 µm thick; ornamentation an orderly alveolate reticulum, the alveolae 5-6-sided, 5-8(-9) along spore length, the corners forming spines (4-)5-7(-8) x 0.5 µm broad, somewhat broader at the base, the alveolar walls uniformly as tall as the spines (fig. 3F, J, N); a "microreticulum" appears in some spores when the microscope objective is focused on the optical cross section but not on the spore wall surface or on SEM micrographs of the surface. Asci in youth globose to broadly ellipsoid to ovoid or pyriform; sometimes the base narrowed stipe-like up to 15 x 7 µm, at maturity globose to broadly ellipsoid or misshapen from the pressure of crowded spores within, hyaline, thin-walled, 60-85 x 65-75 µm, 1-4(-5)-spored, astipitate at maturity,
Peridiopellis 200-300 µm thick plus or minus 80 µm of tightly interwoven hyphae 3-5(-10) µm broad (fig. 5E), the cells short and with subhyaline walls 0.5-1 µm thick, where the interior veins emerge through the peridium the cells often forming a localized tissue of rounded cells up to 12 µm broad; surface pubescence variable, of tangled hyphae and emergent hyphal tips 2-5 µm broad with thin walls, some even and smooth, some with granulated surfaces and some moniliform from walls irregularly thickened by hyaline bands 0.5-1(-2) µm thick. Subpellis abruptly differentiated from the outer layer, 150-220 µm thick, of interwoven, subhyaline, thin-walled hyphae 2-10 µm broad with scattered cells up to 15 µm broad. Gleba of hyaline, thin-walled, interwoven hyphae 2-7 µm broad with scattered cells inflated up to 15 µm.
Distribution, habitat and season. - West of the Cascade Mountains from southern Puget Sound region of Washington south to southwestern Oregon at elevations from near sea level up to 425 m in pure stands of Pseudotsuga menziesii forests up to 100 y old or Pseudotsuga mixed with Tsuga heterophylla, Picea sitchensis or Alnus spp.; often in Christmas tree plantations as young as 5 y. Sep-mid-March.
Collections examined. - USA. Oregon: Benton County, Starker Forests Tum Tum Tree Farm along Oregon 20 near Blodgett. 3 Feb 2007, G. Bonito GB 284, (holotype OSC 131409); 3 km S of Peedee, 150 m. 16 Jan 2003, W. Bushnell 1158, Trappe 27985 (paratype OSC 131479). Clackamas County, Beaver Creek, Paul Bishop's Tree Farm, 185 m. 19 Jan 2002, A.R. Beyerle 1777, Trappe 27173 (paratype OSC 131474) and 30 Mar 2002, A. Beyerle 1790, Trappe 28263 (paratype OSC 131478); Beaver Creek Tree Farm, 180 m. 12 Mar 1994, C. Paapanen, Trappe 15112 (paratype OSC 58516. Columbia County, Scappoose, Holiday Road, 305 m. 23 Jan 2001, A. Beyerle 1343, Trappe 27977 (paratype OSC). Curry County, Cape Sebastian Overlook, 220 m. 14 Nov 1985, G. Menser, Trappe 8767 (paratype OSC 46851); Humbug Mountain State Park, 150 m. 18 Mar 1992, M. Castellano, Trappe 12387 (paratype 50523). Douglas County, Melrose, Ray Dorner Ranch, 380 m. 17 Oct 1982, J. Rawlinson, Trappe 7164 (paratype OSC 40976). Josephine County, Sam Brown Campground, 425 m. 1 Mar 1989, D. Arthur, Trappe 11086 (paratype OSC 49220). Polk County, Falls City, Black Rock Road, 245 m. 10 Jan 2003, A. Beyerle, Trappe 28266 (paratype OSC); S. Fork Peedee Creek, Bald Mountain Road. 5 Nov. 1997, W. Bushnell, Trappe 19957 (paratype OSC 60500). Tillamook County, Cape Lookout State Park entrance, 12 m. 26 Oct 2002, D. Wheeler, Trappe 27945 (paratype OSC). Yamhill County, Lafayette, Trappist Monastery, 105 m. 1998, C. Schneider, Trappe 22699 (paratype OSC). Putnam Creek, Luckiamute Tree Farm, 120 m. 11 Jan 1992, W. Bushnell, Trappe 12327 (paratype OSC 50753). WASHINGTON: Clark County, 3.2 km N of View, 260 m. 29 Oct 1994, D. Wheeler, Trappe 15062 (paratype OSC 58230). Grays Harbor County, Montesano, Stewart Tree Farm. 20 Sep 1997, J. Haseltine, Trappe 22691 (paratype OSC 61282); Wynoochee Willie Tree Farm. 19 Nov 1997, Z. Carter & P. Rawlinson, Trappe 19960 (paratype OSC 60515). Lewis County, Cinnabar Road near Mayfield Lake, 205 m. 12 Sep 1992, N. Wedam, Trappe 12640 (paratype OSC 50999).

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