Dimelaena tibetica M. Ai & Xin Y. Wang, 2022

Ai, Min, Zhong, Qiuyi, Scheidegger, Christoph, Wang, Lisong & Wang, Xinyu, 2022, Revision of Dimelaena Norman (Caliciaceae, Ascomycota) species containing usnic acid reveals a new species and a new combination from China, Phytotaxa 574 (4), pp. 259-272 : 268-269

Dimelaena tibetica M. Ai & Xin Y. Wang , sp. nov. MycoBank No. 841524

Characterized by a grayish yellow surface, usual covered in white pruina, and by a plane, radiate-plicate thallus margin, a crustose, areolate thallus, adnate apothecia and numerous pycnidia.

Type :— CHINA. Qinghai Prov.: Huangyuan Co., 36°39′55.26″N, 101°24′32.23″E, 2430 m, on siliceous rock, 18 May 2018, Wang Lisong et al. 18-58092 ( KUN, holotype!) .

Etymology: The epithet ‘tibetica’ refers to its distribution being mainly in the Tibetan Plateau.

( Fig. 5 )

Thallus crustose, rarely bulging and verrucous, thick or thin, tightly attached to the substrate, areolate at center and plane, radiate-plicate at margin, cracks obvious, areolae large, 2.00–3.00 mm wide; marginal lobes slim and long, up to 4.00 mm long, 1.00 mm wide, tightly attached to the substrate, apex lobes multilobed; thallus grayish yellow with usnic acid in cortex, usually a covering of white pruina near the thallus tip; medulla white, without the lower cortex.

Apothecia cryptolecanorine to lecanorine, one or more apothecia in each areola, sessile, scattered, roundish, 0.20–0.60 mm in diam., disc black, disk margin obvious or concolorous with thallus; epihymenium brown; hymenium hyaline, 50–75 µm high, inspersed with oil droplets; hypothecium hyaline, 75–100 µm high; asci clavate, Bacidia - type, 8-spored; ascospores brown, 1-septate, thin walled, 8–12 × 4–7 μm, markedly constricted at septum when mature.

Pycnidia rare, immersed; conidia bacilliform, 6 × 1 µm.

Chemistry: Usnic, stictic, norstictic and hypostictic acids.

Ecology and distribution: This species usually grows on exposed siliceous rock, at elevations of 1366–4232 m. Distributed in Xizang, Qinghai and Ningxia provinces in China ( Fig. 2 ).

Notes: The new species D. tibetica is similar to D. oreina , but with a plane, radiate-plicate thallus margin, and the apothecia of the new species are raised, the upper surface has a grayish covering of white pruina, and the margins of the areoles are not darkened. The apothecia of D. oreina are innate to adnate, the upper surface is bright yellowish-green without pruina, the edge of the areolae is darkened and pycnidia are numerous. Furthermore, gyrophoric acid has not been reported in D. tibetica while D. oreina in China always contains this compound. Obermayer et al. (2004, Figure 5 ) displayed two types of apothecia in Dimelaena oreina s.l. Based on phylogenetic analysis, these should belong to distinct species: 5A is similar to D. tibetica and 5B is D. altissima .

Additional material studied. CHINA. Ningxia Province: Helan Mt., dakouzi, 1366 m, 38°35′32″N, 105°56′31″E, 24 September 2010, Niu Dongling 10-0259 ( NXAC) ; Helan Mt., Xiangshuigou , 2189 m, 38°46′30.9″N, 105°54′48.8″E, 10 June 2017, Niu Dongling 17-0417 ( NXAC) . Qinghai Province: Huangyuan Co., by the side of the Qinghai Lake, 2441 m, 36°39′57.41″N, 101°24′32.03″E, 18 May 2018, Wang Lisong et al. 18-59122; Huangyuan Co., 2430 m, 36°39′55.26″N, 101°24′32.23″E, 18 May 2018, Wang Lisong et al. 18-58092; Huangyuan Co. , on the route to Qinghai Lake , 2473 m, 36°39′57.15″N, 101°24′32.28″E, 18 May 2018, Wang Lisong et al. 18-58119 . Xizang Province: Gongjue Co., Xiangpi Vil., 3578 m, 31°00′46.41″N, 98°15′24.14″E, 24 September 2020, Wang Lisong et al. 20-68977; Mangkang Co. , Bangda Town beside the G318 national road, 3690 m, 29°27′46.30″N, 98°38′26.57″E, 20 September 2016, Wang Lisong et al. 16-50799; Zhada Co. , Tuolin Town , 4232 m, 31°43′00.68″N, 79°44′56.99″E, 23 July 2019, Wang Lisong et al. 19-65539; Gongjue Co. , Xiangpi Vil., 3590 m, 31°00′45.79″N, 98°15′24.00″E, 24 September 2020, Wang Lisong et al. 20-67410 .

Figures

FIGURE 2. Distribution of species of Dimelaena containing usnic acid in the Tibetan Plateau. Distribution of D. oreina s.l. is from Obermayer et al. (2004).

FIGURE 5. Morphology and anatomy of Dimelaena tibetica (18-58092, KUN). A. Thallus margin of Dimelaena tibetica. B. Straight and plane lobes of radiate- plicate margin. C. Isolated cryptolecanorine apothecia (disc margin obvious). D. Section of apothecium. E. Buellia- type ascospores, constricted at septum. F. Bacidia-type ascus-apex. Scale bars: 1 mm (A, B); 0.5 mm (C); 25 μm (D); 5 μm (E, F).