Tuber aztecorum Guevara, Bonito & Smith

Guevara-Guerrero, Gonzalo, Bonito, Gregory, Smith, Matthew E., Healy, Rosanne, II, Arthur C. Grupe, Cazares, Efren, Castellano, Michael A. & Trappe, James M., 2018, Tuberaztecorum sp. nov., a truffle species from Mexico belonging to the Maculatum clade (Tuberaceae, Pezizales), MycoKeys 30, pp. 61-72 : 63-65

Tuber aztecorum Guevara, Bonito & Smith sp. nov. Figs 1, 2 A–I

Type.

MEXICO. State of Mexico, Toluca-Temascaltepec road, La Puerta, Parque Nacional Nevado de Toluca, 29 July 2010, Guevara 993 (ITCV [ José Castillo Tovar herbarium] - holotype, MSU and FLAS - isotypes), GB KY271791.

Diagnosis.

Tuber aztecorum is a sister species to T. castilloi , but T. castilloi differs by having larger spores, 27-63 × 20-40 µm, is without an irregular thickness to the cell wall on peridial hyphae and is associated mainly with Quercus spp. Also resembles T. guevarai but T. guevarai has narrow spores that are 18-55 × 16-42 µm and cream-yellow fruiting bodies and rDNA variation.

Etymology.

“aztecorum” in reference to the ancient Aztec civilisation of Mexico.

Description.

Ascomata 5-23 × 4-16 × 3-11 mm, subglobose, irregular, lobate or globose, light to orange brown or reddish-brown changing to dark brown when handled, finely verrucose or granulose, with 5-8 verrucae in 1 mm, solid, brittle, surface dry, base sessile. Peridium in cross-section undetachable <.5 mm wide, with one or several basal white to cream furrows or depressions that merge into veins. 5% KOH negative. Gleba marbled, white to greyish, white veins, some veins ending in the peridium. Odour fungoid to raw potato-like, taste not recorded.

Peridium 110-350 µm thick. Outer layer (epicutis) a pseudoparenchyma 62-250 µm thick, of hyphae 5-30 µm diam., versiform, angular or isodiametric, in some areas hyphae arranged perpendicular to the epicutis, hyaline to reddish-brown in mass in KOH, thick-walled (2 µm), without intracellular content. Surface hairs versiform, single hair-like hyphae or cystidia 53-97 µm long × 4-5 µm at the base, tapered to the tip, some with septa, scattered or in clusters, brittle, thin-walled, hyaline in KOH. Other hyphae present are claviform, erect, cylindrical or sinuate with an irregular thickness to the cell wall that resembles knobs or “spines”. Some globose or constricted hyphae emerging from isodiametric hyphae, 3-10 µm wide. Inner layer (subcutis) 50-225 µm thick, of prostrate and interwoven, hyphae gradually intermixing into gleba, hyaline in KOH and trypan blue, hyphae 2 -5 µm wide. Some young specimens show noticeable prostrate cylindrical, claviform or vermiform hyphae along the subcutis that are thick-walled. Veins formed by hyaline, thin-walled, interwoven hyphae.

Ascospores subglobose, globose to broadly ellipsoid, 23-58 × 18-48 µm without ornamentation, alveoli 2-7 µm tall, 7-10 alveolar meshes along the spore length, 5-6 across, polygonal (4-6 sides), cell wall 2-3 µm thick. 1-spored asci have spores that are 42-58 × 27-48 µm, 2-spored asci have spores that are 25-52 × 23-40 µm, 3-spored asci have spores that are 27-40 × 20-30 µm, 4-spored asci have spores that are 23-38 × 18-28 µm, 5-spored asci have spores that are 25-32 × 18-25 µm, yellowish to light brown in KOH and Melzer´s reagent. Asci globose, subglobose to broadly ellipsoid, without pedicel, 62-95 × 57-77 mm, hyaline in KOH, yellowish to brownish in Melzer´s reagent, thin-walled (immature asci thick-walled, up to 7.5 µm thick).

Distribution and Ecology.

MEXICO, state of Mexico La Puerta, National Park Nevado de Toluca. Hypogeous, gregarious in volcanic rock soil in an Abies religiosa forest at 3065 m. N 19°11.662', W099°48.537'. 29 July 2010.

Additional collections examined.

Mexico, state of Mexico, La Puerta, National Park Nevado de Toluca, Guevara 1109 (paratype ITCV1109, GB KY271790), Guevara 1110 (paratype ITCV 1110), 29 July 2010.