Tulostoma beltirense V. Vlasenko, 2025

Tulostoma beltirense V. Vlasenko , sp. nov. Fig. 2 View FIGURE 2 , 3 View FIGURE 3 .

MycoBank: MB 857479.

Diagnosis: —Basidiomata small, grows singly, grayish white, gleba ocher, spores subglobose, regularly verrucose, with flattened, smoothed, large warts, 4.2 × 5.8 μm in diam., 4–5 warts on visible side of spore.

Description: —Basidiomata with subglobose spore-sac, 8 mm wide, 7 mm tall. Exoperidium indistinct, incrusting sand. Endoperidium thin, smooth, light ocher to grayish white. Mouth oval, indistinct. Socket inconspicuous. Stem slender, 3–3.5 mm wide, 12–14 mm tall, grayish white, furrowed to fissured and appressed. Mature gleba ocher. Capillitial threads 1.8–5.6 µm wide, hyaline in KOH, undulating, irregular thickness, thick-walled, with uneven inner walls, ramified, septa rare, slightly widened up to strongly widened. Hyphae of exoperidium 1.5–6.0 μm wide, hyaline in KOH, septate. Hyphae of endoperidium 1.5–5.0 μm wide, hyaline in KOH, septate, ramified. Hyphae of stipe context 4–7.5 μm wide, hyaline in KOH, septate, non-ramified. Hyphae of stipe scales 3.5–7 μm wide, hyaline in KOH, septate, non-ramified. Spores in transmitted light subglobose, uneven, thick-walled, 4.20 (4.70) 5.40 × 4.60 (5.15) 5.80 μm without ornamentation; 5.20 (5.80) 6.60 × 5.80 (6.35) 7.40 μm including ornamentation; light brown with brownishgreenish protoplast in KOH. Ornamentation not visible in KOH; more contrasting with a slightly noticeable fine wart ornamentation in polyvinyl lactophenol. Spores under SEM subglobose, regularly verrucose, 4.3 (4.5) 4.7 × 4.7 (4.85) 5.0 μm including ornamentation. Warts large, 4–5 on visible side of spore, 0.2–0.25 μm wide, 0.4–0.5 μm length under SEM, flattened, smoothed, more or less isolated or merging with small warts or forming ridge-like anastomoses at the base, visible on SEM.

Etymology: —Referring to the type locality—Stary Beltir Village in Republic of Altai. Holotype: — RUSSIA. Republic of Altai, Kosh-Agach district, 11 kilometers West of the Stary Beltir Village,

49°57.431’N, 88°02.868’ E, 2084 m a.s.l, rocky steppe, on soil, 15 September 2020, leg. V. Vlasenko, NSK 1014740,

GenBank: PP992070 (ITS), PP992071 (28S). Other specimens examined: — RUSSIA. Republic of Altai, Kosh-Agach district, 11 kilometers West of the Stary Beltir Village, 49°57.600’N, 88°02.950’ E, 2040 m a.s.l, rocky steppe, on soil, 15 September 2020, leg. A. Vlasenko, NSK 1014743.

Ecology and distribution: —Distributed in the rocky mountain steppes of the South-Eastern Altai. Grows singly, not in groups.

Comments: —The new species is macromorphological very close to Tulostoma kotlabae , T. morenoi , T. lysocephalum , T. melanocyclum and T. calcareum Jeppson, Altés, G. Moreno et E. Larss. (2017: 46) . Representatives of this group have small spore-sacs on a thin long stalk, white and grayish shades. For differentiation of species, the sizes and ornamentation of spores in SEM should be used.

Tulostoma beltirense significantly differs from T. kotlabae , T. morenoi and T. lysocephalum in size and spore ornamentation ( Table 2). Basidiospores of Tulostoma beltirense are similar in size to T. kotlabae , 4–5 μm in diam. without ornamentation, with 4–5 warts on visible side of spore; but the warts on spores of T. beltirense are smaller in size, without pyramidal spines, flattened, smoothed, while T. kotlabae has larger warts with pyramidal spines ( Tomaszewska 2011, El Kholfy et al. 2017, Jeppson et al. 2017). Basidiospores of Tulostoma lysocephalum are larger, 5.6–6.6 µm in diam., warts on the spores large, in the form of pyramidal spines, 7–8 warts on visible side of spore ( Wright 1987, Jeppson et al. 2017). Basidiospores of Tulostoma morenoi the largest, 5.6–9.2 μm in diam., more sparsely spaced than T. lysocephalum , warts on the spores large, without pyramidal spines, smoothed, there are small warts between them.

Tulostoma melanocyclum and T. calcareum Jeppson, Altés, G. Moreno et E. Larss. (2017: 46) are characterized by verrucose-echinate basidiospores.