Dimelaena altissima (H. Magn.) 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 : 264-265

Dimelaena altissima (H. Magn.) M. Ai & Xin Y. Wang , comb. nov. MycoBank no. 841532

Rinodina altissima H. Magnusson (1940: 155) .

Type:— CHINA. Gansu Province: Taben-Buluk , 4000 m, 1931, Birger Bohlin 35a ( S, holotype!) .

Rinodina altissima var. exalbescens H. Magnusson (1940: 156) ; Dimelaena oreina var. exalbescens (H. Magn.) Wei (1991: 89) .

Type:— CHINA. Gansu Province: Ehr-tao-ch’uan (Nan-shan), at about 4200 m, on rock facing the South , 5 January 1932, Birger Bohlin 74b ( S, holotype!) .

( Fig. 3 )

Thallus crustose, thick or thin, closely attached to the substrate, areolate at center and radiate-plicate at margin, areolae 0.55–0.90 mm wide, sometimes darkened around the areolae; marginal lobes flat and narrow, <3.00 mm long, c. 1.50 mm wide, tightly attached to the substrate, sometimes darkened around the tips; thallus yellowish green with usnic acid in cortex but sometimes lighter to pale yellowish white, medulla white, without the lower cortex.

Apothecia cryptolecanorine to lecanorine, immersed, often touching each other, irregularly rounded, 0.18–0.63 mm in diam., disc black, disc margin not obvious or absent; epihymenium brown; hymenium hyaline, 60–80 μm high, inspersed with oil droplets; hypothecium hyaline, 80–135 μm high; asci clavate, Bacidia - type, 8-spored; ascospores brown, 1-septate, thin walled, 8.5–13 × 4.5–7 μm, markedly constricted at septum when mature.

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

Chemistry: Usnic and gyrophoric acids, sometimes with hypostictic, stictic and norstictic acids.

Ecology and distribution: This species usually grows on exposed siliceous rock, at elevations of 2737–4805 m. Distributed in Sichuan, Xizang, Qinghai and Gansu provinces in China ( Fig. 2 ).

Notes: Dimelaena altissima is characterized by having a plane lobed thallus margin, tightly attached to the substrate, innate and irregularly rounded apothecia. It differs from D. oreina by lacking convex marginal lobes and well-defined apothecia margins. Sheard & Ahti (1975) regarded Rinodina altissima as a synonym for D. oreina due to similar anatomical features, and because morphological characters did not correlate with chemical ones. Obermayer et al. (2004) agreed with this treatment. Now, however, morphological differences, supported by molecular data, lead to the division of these species. There is no reason to subsume several chemotypes within a species. Gyrophoric acid was detected in D. altissima . In addition, stictic acid and hypostictic acid were detected in some specimens.

Additional specimens examined. CHINA. Gansu Province: Sunan Co., on the route from Sunan to Qilian , 3479 m, 38°39′16.58″N, 99°29′30.87″E, 30 May 2018, Wang Lisong et al. 18-59774 ; Sunan Co., on the route from Sunan to Qilian , 3928 m, 38°37′45.45″N, 99°28′31.76″E, 30 May 2018, Wang Lisong et al. 18-58855 ; Subei Co., Nanshan Mt., near 29th Mengke Glacier , 3392 m, 39°13′52.53″N, 95°24′18.40″E, 23 May 2018, Wang Lisong et al. 18-58543 . Qinghai Province: Huangyuan Co., on the route to Qinghai Lake , 2737 m, 36°45′54.72″N, 101°08′05.79″E, 18 May 2018, Wang Lisong et al. 18-59138 ; Huzhu Co., beside Weibei road, 3060 m, 37°00′26.52″N, 102°08′16.81″E, 31 May 2018, Wang Lisong et al. 18-59930 ; Qilian Co., on the route from Sunan to Qilian , 2807 m, 38°13′44.92″N, 99°59′48.79″E, 30 May 2018, Wang Lisong et al. 18-59878 ; Zaduo Co. , 4090 m, 32°52′43.78″N, 95°20′28.55″E, 20 September 2020, Wang Lisong et al. 20-68622 . Sichuan Province: Rangtang Co., Haizishan, 4237 m, 32°20′02.40″N, 101°25′00.23″E, 9 June 2020, Wang Lisong et al. 20-66696 . Xizang Province: Cuoqin Co., 4805 m, 31°11′37.70″N, 85°03′32.37″E, 20 July 2019, Wang Lisong et al. 19-65370 ; Kangma Co., Nanni Vil., 4136 m, 28°46′16.29″N, 89°38′48.64″E, 24 July 2019, Wang Xinyu et al. xy19-1416 ; Zhongba Co. , Zhuzhu Vil., 4647 m, 29°47′17.16″N, 83°54′09.76″E, 25 July 2019, Wang Lisong et al. 19-63935 ; Zhongba Co. , Zhuzhu Vil., 4650 m, 29°47′17.29″N, 83°54′09.74″E, 25 July 2019, Wang Lisong et al. 19-63938 ; Zhongba Co. , Zhuzhu Vil., 4639 m, 29°47′16.57″N, 83°54′09.61″E, 25 July 2019, Wang Lisong et al. 19-63927 ; Kangma Co. , Nanni Vil., 4120 m, 28°46′14.32″N, 89°38′48.78″E, 24 July 2019, Wang Xinyu et al. XY19-2343 ; Yadong Co. , Kangbu Vil., 4039 m, 27°45′41.83″N, 88°58′58.41″E, 27 July 2019, Wang Xinyu et al. XY19-1719 .

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 3. Morphology and anatomy of Dimelaena altissima (18-58855, KUN). A. Thallus of Dimelaena altissima. B. Straight and plane lobes of radiate-plicate margin. C. Cryptolecanorine apothecia. 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 (E); 5 μm (E, F).