Rhizoplaca auriculata Y. Y. Zhang, Li S. Wang & Printzen, 2024

Zhang, Yanyun, Yin, Yujiao, Wang, Lun, Printzen, Christian, Wang, Lisong & Wang, Xinyu, 2024, Two new species of Rhizoplaca (Lecanoraceae) from Southwest China, MycoKeys 101, pp. 233-248 : 233

Rhizoplaca auriculata Y. Y. Zhang, Li S. Wang & Printzen sp. nov.

Fig. 3

Type.

China. Yunnan Prov.: Deqin Co., Benzilan Vil., besides Jinsha River , 28°11′N, 99°21′E, 2099 m, on chloritoid schist, 19 August 2018, Li S. Wang et al. 18-60139 (KUN-L0065413) .

Diagnosis.

The species is characterized by the yellowish green upper surface, ear-like marginal squamules containing a bluish-black and wide, free lower margin, the lack of lower cortex, and the persistently orange apothecia with constricted base.

Etymology.

The epithet refers to the ear-like margins of marginal squamules.

Description.

Thallus squamulose to placodioid, umbilicate at least when young, rosulate or not, 2-5 cm across, centrally squamulose, squamules continuous to irregularly overlapped, slightly convex, 1-2.5 mm across, marginal squamules radiating or not, larger than the center, 2-4 mm across, with ear-like margins. Upper surface yellowish green, epruinose to only pruinose at margins of squamules, smooth to rugose, lower surface with a bluish-black free margin, 1-3 mm wide, no tomentum. Upper cortex 16-22 μm thick, filled with pale brown granules, soluble in K, upper part with scattered brown granules, insoluble in K, consisting of thin-walled and short-celled hyphae, 2-3 μm in diam., length of cell 3-7 μm, epinecral 10-25 μm thick, filled with brown granules, soluble in K, algal layer continuous, 67-80 μm thick, filled with black substance, insoluble in K, algae 8.5-12 μm in diam., medulla filled with black substance, insoluble in K, lower cortex lacking.

Apothecia common, laminal, scattered to slightly grouped, lecanorine, sessile, constricted at base, 0.5-2 (3) mm in diam., disc orange, pruinose, plane to slightly convex, thalline margin entire, 0.1-0.2 mm wide, concolorous with thallus, pruinose. Hymenium filled with orange and gray granules, insoluble in K, 75-87 μm high, epihymenium non-gelatinized, filled with brown (soluble in K) and orange granules (insoluble in K), not interspersed, 12.5-19 μm thick, parathecium extremely reduced, subhymenium with gray granules, insoluble in K, 17-30 μm, hypothecium colorless, with grouped brown granules, insoluble in K, 60-100 μm, algae under hypothecium continuous to irregularly grouped, cortex of thalline margin same as upper cortex, even, 25-30 μm thick, paraphyses simple to slightly branched, ca. 3 μm in diam., septate, length of cell 9-14 μm, tips slightly thickened, asci clavate, 62-75 × 15-21 μm, ascospores broadly ellipsoid to subfusiformis, hyaline, 10-16 × 6.5-9.5 μm. Pycnidia immersed in the thallus, ostioles not seen, conidia filiform, straight to curved, 22.5-37.5 × 0.7 μm.

Chemistry.

K+ pale yellow, C-, P-; usnic and placodiolic acids detected in TLC.

Distribution and ecology.

The new species only grows on dry and exposed calcareous chloritoid schist at elevation of 2000-2108 m beside the Jinsha River in Sichuan and Yunnan Provinces, China.

Notes.

Rhizoplaca callichroa is similar to this new species in thallus and apothecia size but differs by its pale brown, lower free margins ( Zhang et al. 2020) and the substratum of hard calcareous rock in karst landform. R. huashanensis shares yellowish green upper surface and black lower surface with R. auriculata , but differs in the presence of a lower cortex, black apothecial discs, smaller ascospores (11.55-12.32 × 6.93-7.70 μm), and the absence of placodiolic acid ( Wei 1984). R. chrysoleuca differs from R. auriculata in its thallus with gelatinized lower cortex and the smaller ascospores (7.5-11.5 × 4-5.8 μm). R. adpressa differs from R. auriculata in its thallus with areolate center and squamulose margins, pale green upper surface with white heavy pruina, the lower surface with white free margins, and the adnate apothecia with orange to reddish-brown discs.

Additional specimens examined.

China. Sichuan Prov.: Derong Co., Benzilan Vi., besides Jinsha River , 28°12′N, 99°20′E, 1960 m, on chloritoid schist, 4 October 2009, Li S. Wang & J. Wang 09-31121 (KUN-L0048841) . Yunnan Prov.: Deqin Co., Benzilan Vi., besides Jinsha River , 28°11′N, 99°21′E, 2099 m, on chloritoid schist, 19 August 2018, Li S. Wang et al. 18-60136 (KUN-L0065415), 18-60336 (KUN-L0065496), same location, 2108 m, on chloritoid schist, 19 August 2018, Li S. Wang et al. 18-60352 (KUN-L0065512), 18-60355 (KUN-L0065515), same location, 28°23′N, 99°01′E, 2000 m, on chloritoid schist, 31 October 2015, Li S. Wang, Y. Y. Zhang & M. X. Yang 15-49794 (KUN-L0040537), 15-49796 (KUN-L0040538), same location, 28°10′N, 99°23′E, 2115 m, on chloritoid schist, 27 August 2006, Li S. Wang, Oh Soon-OK & D. L. Niu 06-26670 (KUN-L0040471), 06-26684 (KUN-L0040575), same location, 28°10′N, 99°31′E, 2110 m, on rock, 27 August 2006, H. Harada 23764 (KUN-L0051510) .

Figures

Figure 3. Rhizoplaca auriculata (KUN-L 0065413) A holotype B section of apothecia (K and LCB) C asci and ascospores (Lugol's solution) D ascospore (water) E upper cortex and epinecral (K and LCB) F lower surface with bluish-black hyphae lacks lower cortex (LCB). Scale bars: 20 μm (B); 5 μm (C, D); 10 μm (E, F).