Tuber depressum S.P. Wan, 2017

Wan, Shanping, Xu, Wenjun, Tan, Nianwu, Wang, Yun, Zheng, Yi & Yu, Fuqiang, 2017, Three Excavatum species Tuber badium, T. depressum and T. verrucosivolvum from Sichuan Province, China, Phytotaxa 296 (3), pp. 228-238 : 233-234

Tuber depressum S.P. Wan , sp. nov. ( Fig. 4 ).

MycoBank:—MB 818795

Type:— CHINA. Sichuan Province: Huidong County, in soil under forest dominated by Pinus armandii, Dec. 2012 , wsp098, HKAS 95396.

Ascomata subglobose, 1.5–3 cm in diam., firm, with typical basal cavities, covered with distinctly verrucose warts in some areas, especially at the surface of cavity area, yellow brown to brown; interior cavity surface covered with many fine, irregular scales and large warts, white to yellow when fresh. Peridium 200–640 μm thick including the 3–88 μm high verrucose warts, pseudoparenchymatous, the outer layer 30–290 μm thick composed of big, subglobose to subangular cells, 2–21 × 1.5–17 μm, pale brown or hyaline; the inner layer 90–540 μm thick, composed of intricately interwoven, hyaline and thin-walled hyphae, 1.5–6.5 μm in diam. Gleba solid, yellowish brown when mature, marbled with white-yellow veins. Gleba composed of hyaline, interwoven, thin-walled hyphae, 1–6.5 μm broad at the septa, the cells cylindrical interwoven to inflated, 2.5–16 × 2–7.5 μm. Odor pleasant. Taste not recorded. Asci globose to subglobose, pyriform, ellipsoid or irregular, 94–111(–114) × 81–93(–100) μm, hyaline, sessile or with a short or tall stalk, thin walled 1–2 μm thick, 1–5 spored. Ascospores ellipsoid, fusiform, broadly ellipsoid, sometimes subglobose, hyaline when young, becoming brown at maturity; excluding their alveolate-reticulate ornamentation, in 1-spored asci 42.5–52.5(–55) × 29–34(–38.5) μm, in 2-spored (28.5–)30–48.5(–50) × 23–31.5(–32) μm, in 3-spored 32–46(–49) × 24–31(–32) μm, in 4-spored 23.5–41(–41.5) × (23–)24–29(–30) μm, and in 5-spored (25–)27–38(–42) × 21–27.5 μm; Q = 1.1–1.7, Qm = 1.42 ± 0.14; reticulum with 2–5 meshes along the spore length and 2–3 across, the alveolar walls up to 2–9 μm tall.

Diagnosis: — Tuber neoexcavatum differs in its prosenchymatous peridium, 2–4 spored asci and the absence of subglobose ascospores.

Habit, habitat and distribution: —Hypogeous, in soil under forest dominated by P. armandii in Sichuan Province, China. Only known from China.

Etymology: —In reference to the distinctly verrucose warts of the ascoma.

Other material examined: — CHINA. Sichuan Province: Huidong County, in soil under forest dominated by P. armandii, Dec. 2012 , wsp093, HKAS 88895, ibid., wsp094, HKAS 88896, all collected by S.P. Wan. CHINA. Sichuan Province, Huidong county, 3 Nov. 2006, CJ411, HKAS 52006, collected by J. Chen.

Figures

FIGURE 4. Tuber depressum (HKAS 95396, holotype). a, c. Ascomata and sections. b. Surface warts of ascoma d. Peridium sections. e. Scanning electron micrograph of ascospore. f. Light micrograph (LM) of asci and ascospores.