## 3 Results
### Taxonomy
XY21-274 KUN, **B**: [PERSON] 32,914 H-NYL, **(D–G)**: [PERSON] et al. 21-7042 KUN); **(A)**, habit of _P. simensis;_ **(B)**, type of _P. simensis;_ **(C)**, foliose thallus when dry; **(D)**, apothecium; **(E)**, white lower surface with rhizies; **(F)**, transversal sections of the thallus; **(G)**, transversal sections of the apothecium; **(H)**, ascus. Scale bars: 5 mm (**B**,**C); 2 mm (**D**,**E); 50 μm (**F**); 200 μm (**G**); 30 μm (**H**). Type: BM000975901 (type, collected by [PERSON] on 27 April 1803)  
Diagnosis: This species has a reduced thallus, often with white prunia; this morphological character is shared with _Solarina embelina_, but _P. spongiosa_ has four spores per ascus, whereas _Solarina embelina_ only has one. Description: Thallus: foliage, fragile, dorsiventral, heteromerous, poorly developed, restricted to a continuous or lacerate narrow rim surrounding the apothecium, 0.1-0.7 cm in diam. ; Upper surface: bright green when wet, dark green to pale grey when dry, usually covered with white prunia; Upper cortex: parapelectenchymatous, colorless, 10-20 \(\upmu\)m thick; Medulla: 40-80 \(\upmu\)m thick; Photobiont: _Cocomyxa_ and _Nostoc_, one _Cocomyxa_ green-algal layer, 20-60 \(\upmu\)m thick, _Nostoc_ present in internal cephalodia which can be seen on the underside of the thallus as dark spots; Lower cortex: lacking; Lower surface: pale brown, densely lomentose, not or indistinctly veined, rhizines; Apothecia: rounded, irregularly scattered, sunk in depressions in the upper surface, red-brown to black, medially concave, thalline margin absent; Asci: clavate, _Peltigera_-type, 4-spored; Ascospores: red-brown or dark brown, 1-septate with a median constriction, ellipsoid to fusiform, wall non-uniformly thickened, surface ornamented broad reticulating ridges and irregular lacunae, measured 30-50 \(\times\) 18-23 \(\upmu\)m.  
Chemistry: No lichen products detected by TLC. Ecology and distribution: This species typically thrives in moist calcareous soils within the alpine zone and is commonly found beneath the edges of groves. It is distributed in America [43], Austria [74], Canada [44], France [46], Germany [47], Greenland [48], Iberian Peninsula and Balearic Islands [49], Ireland [51], Poland [56], Russia [57], the Czech Republic [59], Ukraine [60]. Note: This species exhibits morphological similarities with _Solarina embelina_, particularly in their thallus structure, where reduced thalli form a distinct small circle around the apothecium. However, the two species differ in terms of spore number: _S. embelina_ contains only one spore per ascus, whereas _P. spongiosa_ possesses four spores per ascus. Through a meticulous review and comparison of the original literature on _Lichen spongiosus_, we have identified discrepancies between the initial documentation of this species and the present specimens. The original records describe the species as having a clustered and branched thallus; apothecia that are scattered, concave, brown, externally spongy, and pale, with a thin, upright margin. In contrast, current samples of _P. spongiosa_ feature a small thallus, lacking lobes and apothecia that are scattered, concave, brown to black, without any margin. However, due to limited access to the holotype of _Lichen spongiosus_, we are unable to define this species. However, our samples are phylogenetically and morphologically identical to the currently accepted species _Solarina spongiosa_. Consequently, we have opted to retain the classification of this species as _P. spongiosa_. Specimens examined: China, Yunnan Prov., Shangrila city, Biorg Valley, 26\({}^{\circ}\)39\({}^{\prime}\)04.26\({}^{\prime\prime}\) N, 99\({}^{\circ}\)44\({}^{\prime}\)13.77\({}^{\prime\prime}\) E, Alt. 3047 m, 15 July 2023, [PERSON] et al., 23-75281(b); Dali city, Cangshan Geopark, 25\({}^{\circ}\)41\({}^{\prime}\)42.09\({}^{\prime\prime}\) N, 100\({}^{\circ}\)06\({}^{\prime}\)29.97\({}^{\prime\prime}\) E, Alt. 3092 m, 19 May 2024, [PERSON] et al., 24-76095, 24-76098 (a), 24-76097, 24-76099.