Tuber magnatum Picco MZ 1788
Creators: name: Leonardi, Marco
name: Iotti, Mirco
name: Mello, Antonietta
name: Vizzini, Alfredo
name: Paz-Conde, Aurelia
name: Trappe, James
name: Pacioni, Giovanni
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Fungi
Ascomycota
Pezizomycetes
Pezizales
Tuberaceae
Tuber
Tuber magnatum

description: Tuber magnatum Picco
(Figs 4C; 5E, F)
Melethemata inauguralia: 79 (1788).
Tuber griseum Borch ex Pers., Synopsis Methodica Fungorum: 127 (1801); sanct. Fr., Systema Mycologicum 2 (2): 292 (1823). (MB 179335).
MYCOBANK NUMBER. — MB 184470.
GENBANK. — MZ423175 (nrITS), MZ458419 (nr β- tubulin), MZ458423 (nrEF 1-α).
NEOTYPE OF TUBER MAGNATUM PICCO. — Italy. Piedmont, Montechiaro D’Asti, Loc. Seria, 45°00’30”N, 8°06’45”E, lowland grove with Quercus robur L. and Populus tremula L., under Q. robur, 29.IX.2019, four ascomata, leg. Pino Panzini, det. Alfredo Vizzini (neo-, TO[HG3458] here designated; MycoBank Typification number: MBT 10001896).
DESCRIPTION
Ascomata
Hypogeous, globose to lobate or flat, up to 10-15 cm broad and more rarely with a detachable basal mycelial cluster.Peridium whitish (FFFFF0 ivory), yellowish, pale ocher (FFD700 gold, DAA520 goldenrod) more or less greyish (DCDCDC gainsboro, D3D3D3 light gray) sometimes with greenish or reddish hues; smooth surface finely grainy under a lens.
Gleba
Whitish (FFFFF0 ivory), yellowish or pale ocher, brownish (8B4513 saddle brown, A0522D sienna, F2F2F2) with greyish tones, often with reddish purple spots; veins thin, whitish, branched, anastomosing, sometimes forming white gangliform thickenings.
Odor
Pleasant, penetrating, of garlic or strong cheese; taste pleasant.
Peridium
200-500 Μm thick, entirely pseudoparenchymatous basically of globular cells; exoperidium 80-110 Μm in the outer layer with globose cells having walls up to 4 Μm thick and slightly yellow; peridial surface with infrequent stocky, cylindrical-clavate dermatocystidia 14-20 × 8-10Μm; endoperidium 120-380 Μm thick, of thin-walled globose and polygonal cells 6.0-36 × 6-23 Μm with rare cylindrical cells 6-9 × 14-20 Μm.
Asci
Globose, short-stalked or sessile, 60-90 × 40-70Μm (Fig. 2F), with walls up to 4 Μm thick and a basal crozier, containing 1-4 spores.
Ascospores
Alveolate, globose to broadly ellipsoid, Q 1.05-1.33, 20-50 × 15-42 Μm excluding ornamentation, inversely proportional in size to the number of spores in the ascus, yellowish, pale ocher or sometimes light yellow-brown; reticulum with 1-3 regular or coarsely irregular, 3-6 sided alveoli 10-22 Μm wide and 4-5 (-8) Μm high, sometimes with ridges within the alveolae.
Endosporium
Often two-layered in KOH.
Glebal
Hyphae hyaline, 4-8 Μm broad, in the external veins with cylindrical or clavate-elongated cells mixed with subglobose cells 5-42 × 4-16 Μm.
HABITAT. — moist (mesophilic) woods mainly with broad-leaved trees and conifers such as Abies alba Mill., on sandy-silty soils in southern Europe (Italy and a few neighbouring French and Swiss areas, the Balkan-Pannonia region, Northern Anatolia), from late summer to early winter (Belfiori et al. 2020; unpublished data). It has also been reported in Thailand, but vouchers have not been made available (Suwannarach et al., 2017).
NOMENCLATURE AND TAXONOMY
The name most frequently used for this species is Tuber magnatum Picco (1788) for which a neotype is herein designated. However, a competing name exists, namely Tuber griseum Borch ex Pers., validated by Persoon (1801) and sanctioned by Fries (1823), for which a lectotype and epitype are also herein designated. The epitype is represented by a T. magnatum with a greyish peridium.
Borch’s or Picco’s authentic specimens were not available for either T. griseum or T. magnatum.
LECTOTYPE OF TUBER GRISEUM. — Truffe grise De Borch, Lettres sur les Truffes du Piémont, 1 st figure (1780); here reprinted in Appendix 4 (here designated; MycoBank Typification number: MBT 10001897).
EPITYPE OF TUBER GRISEUM. — Italy. Piedmont, Monte Magno, 44°59’02”N, 8°19’35”E, under Quercus robur, 07.XII.1998, one fragment, leg. Virgilio Gavazza, det. Alfredo Vizzini (epi-, TO [HG 3557] here designated; MycoBank Typification number: MBT 10001898).
A proposal will be written to conserve the name T. magnatum and reject the sanctioned name T. griseum.
description: Published as part of Leonardi, Marco, Iotti, Mirco, Mello, Antonietta, Vizzini, Alfredo, Paz-Conde, Aurelia, Trappe, James & Pacioni, Giovanni, 2021, Typification of the four most investigated and valuable truffles: Tuber aestivum Vittad., T. borchii Vittad., T. magnatum Picco and T. melanosporum Vittad., pp. 149-170 in Cryptogamie, Mycologie 20 (9) on pages 160-161, DOI: 10.5252/cryptogamie-mycologie2021v42a9, http://zenodo.org/record/7826657