Tuber aestivum Vittad.

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., Cryptogamie, Mycologie 20 (9), pp. 149-170 : 151-154

Tuber aestivum Vittad.

( Figs 3 ; 4A ; 5A, B ; Appendix 1 )

Monographia Tuberacearum: 38 (1831).

MYCOBANK. — MB 218597.

GENBANK. — MZ423173 (nrITS), MZ458417 (nr β- tubulin), MZ458421 (nrEF 1-α).

LECTOTYPE OF TUBER AESTIVUM VITTAD. — Vittadini 1831: tab. II fig. IV C, D (here designated; MycoBank Typification number: MBT 10001890 ; Fig. 3 ).

EPITYPE TUBER AESTIVUM VITTAD. — Italy. Lombardy, Monza, Parco Villa Reale, sub Tilia cordata Mill. , 8.IX.2019, 45°37’09”N, 9°16’48”E, five ascomata, leg. Stefano Seghezzi, det. Giovanni Pacioni (epi-, AQUI[AQUI 10150], here designated; MycoBank Typification number: MBT 10001891).

Authentic Vittadini specimens examined: K(M) 254890, TO and UPS (F-628206).

DESCRIPTION

Ascomata

Hypogeous, globose or irregular, up to 10 cm in diameter or more, rarely with a flat or slightly basal excavation, surface of peridium black to very dark gray (#000000 to 333333) in both mature and immature specimen, covered with pyramidal warts polygonal at the base, with 4-7 sides, 3-13 mm wide × 0.5- 5.0 mm high, generally acute but often depressed or concave, with sharp edges or with longitudinal radial fissures, surface of the warts typically with evident parallel transverse streaks.

Gleba

Firm and compact, whitish (FAE5D3 light greyish orange) to more or less brown ( E59866 soft orange, 6E2C00, very dark orange, brown tone) in relation to season, habitat or state of ripeness, with abundant ramified and thin, sterile, white veins not discolouring when exposed to the air.

Odor

Weak, similar to stigmas of maize in the whitish gleba of not quite mature specimens, then more and more intense and pleasant like the flavour, which resembles that of nuts, mainly hazelnuts.

Peridium

200-480 Μm thick, exoperidium pseudoparenchymatous (100- 180 Μm), almost opaque in section, composed of globosepolygonal cells, 7-20 Μm wide, with reduced cell lumen and deep brown walls up to 4 Μm thick and fused with those of adjacent cells; endoperidium 100-300 Μm thick, pseudoparenchymatous in the interior part of the endoperidium, the cells hyaline and smaller with a confusing pattern in contact with a layer of intertwined thin (2-3 Μm) hyphae that extend into sterile veins of the gleba.

Asci

Globose to subglobose, 60-120 × 55-85Μm, with walls usually up to 3 Μm thick, rarely to 10 Μm, shortly stalked or sessile, 60-100 × 50-80Μm, with basal crozier, containing 1-6 spores.

Ascospores

Subglobose to broadly ellipsoid, Q 1.21-1.37, 20-45 × 18-35 Μm excluding ornamentation, inversely proportional in size to the number of spores in the ascus, light brown reticulate, meshes 4-10 Μm wide × 3-7 Μm high, 3-5 across the spore width and often with an incomplete secondary crest inside, and with the top of the ornamentations sometimes hooked at the apex of the reticular knots.

Endosporium

Often two-layered in KOH.

Glebal

Hyphae hyaline, 2-8 Μm wide.

HABITAT. — Europe from southern Europe to Ireland, Great Britain and Sweden (Gotland Isle) and East to the Caucasus Mountains, North Maghreb (rare), near and north middle Asia to Turkmenistan / Iran borders. Under broadleaved and coniferous trees and shrubs; its ascomata develop a bit throughout the year, commonly from summer to late autumn ( Molinier et al. 2016; unpublished data).

NOMENCLATURE AND TAXONOMY

Although the nomenclature of Tuber aestivum is seriously compromised due to its frequent use in the wrong sense, the name Tuber aestivum proposed by Vittadini (1831) clearly connected to Micheli’s taxon (1729). It is so well characterized morphologically that past mycologists and traders have always preferred it to valid antecedent synonyms such as Tuber blotii Eudes-Desl. (1824) , Mémoires de la Société Linnéenne de Calvados 1824: 47 (1824) [MB 102874] ( Maire 1930).

However, the early legitimate homonym Tuber aestivum (Wulfen) Spreng. 1827 [MB 218548] exists; consequently Tuber aestivum Vittad. is illegitimate (Art. 53.1). The basionym of this earlier homonyn is Lycoperdon aestivum Wulfen , in Jacquin, Collnea bot. 1 (2): 349 (1787) [1786] [MB 162907]. The Wulfen’s description ( Appendix 3 ) clearly identifies the fungus as a Rhizopogon for which there is the sanctioned name Rhizopogon aestivus (Wulfen) Fr. (1823) . Tulasne & Tulasne (1851) included Rhizopogon aestivus as a synonym of their Rhizopogon rubescens , whose current name is R. roseolus (Corda) Th.Fr. , and as such sometimes subsequently considered to include as synonymous the names Lycoperdon aestivum or Tuber aestivum (Wulfen) Spreng. ( Saccardo 1888) . Martin (1996) examined all the specimens labeled as R. aestivus present in the main European herbaria, determining them as R. roseolus .

Wulfen himself concludes that it is not the species described by Micheli both for size and for the very black external surface with large pyramidal warts, smell and taste. In fact, Lycoperdon aestivum had a smooth peridium, furfuraceous at best, thin and often cracked, whitish then reddish, like a potato, slightly brownish and finally blackish [‘ extus sordide albidum, & ex albido obsolete subrubescens, instar pomorum terrae (Solanum tuberosum L.), dein dilute fuscens, nigrans denique; glabrum… cuticula tenerrima, hinc inde disrupta, & exstans, squamules exhiberet furfuraceus …], spongy gleba cellulose-porous at first white then almost ashy, brownish, blackish (Caro intus spongiosa, subcoriacea, prima alba, tum obsolete, & triste ex albido subcinerascens, fuscescens, subnigricans… celluloso-porosa), without marked smell and without taste (‘ Odor recentium nullus, aut certe debilissimus & subnauseosus. Sapor nullus, nisi imaginarius’).

No specimens of this species have been found in the herbaria of Wulfen (W), Fries (UPS) and KPJ Sprengel (VH/de), for this reason we selected as neotype of Lycoperdon aestivum a specimen of Rhizopogon roseolus collected in Carinthia. ( Austria), place of origin of Lycoperdon aestivum .

A proposal will be written to conserve the name Tuber aestivum Vittad. and reject the legitimate early homonym Tuber aestivum (Wulfen) Spreng. and the early synonym Tuber blotii Eudes-Desl.

The proposal to retain the name Rhizopogon roseolus (Corda) Th. Fr. against Rhizopogon aestivus (Wulfen) Fr. should also be considered.

NEOTYPE OF LYCOPERDON AESTIVUM WULFEN. — Austria. Carinthia, St. Mergereten, Gotschich, leg. Irmegard Krisai Greilhuber, 9.IX.1998, sub nomine Rhizopogon roseolus (neo-, WU[WU 25744], here designated; MycoBank Typification number: MBT 10001892).

Figures

FIG. 3. — Table II, lectotypes of Tuber melanosporum Vittad.(red arrowed) and Tuber aestivum Vittad.(black arrowed).

FIG. 4. — Ascomata of A) epitype of Tuber aestivum Vittad. (AQUI 10150);B) epitype of T.borchii Vittad.(AQUI 10151);neotype of T.magnatumVittad (TO HG3458); epitype of T. melanosporum Vittad. (AQUI 10152). Scales bars: 1 cm.

FIG. 5. — Cross sections of peridia, asci and spores A, B, Tuber aestivum epitype; C, D, T. borchii epitype; E, F, T. magnatum neotype; G, H, T. melanosporum epitype. Scales bars A, C, E, G, 50 µm; B, D, F, H, 20 µm.

APPENDIX 1. — Surface of an ascoma of Tuber aestivum Vittad. showing transverse streaks in peridium warts.

APPENDIX 3. — Wulfen’s description of Lycoperdon aestivum basionym of Rhizopogon aestivus (Wulfen) Fr.(1823) and Tuber aestivum (Wulfen) Spreng.(1827).