Understanding the evolution of phenotypical characters in the Micarea prasina group (Pilocarpaceae) and descriptions of six new species within the group Author Guzow-Krzeminska, Beata Author Serusiaux, Emmanuel Author van den Boom, Pieter P. G. Author Brand, A. Maarten Author Launis, Annina Author Lubek, Anna Author Kukwa, Martin text MycoKeys 2019 57 1 30 http://dx.doi.org/10.3897/mycokeys.57.33267 journal article http://dx.doi.org/10.3897/mycokeys.57.33267 1314-4049-57-1 E8486646121F5D698F78361F5CE84017 Micarea isidioprasina Brand, van den Boom, Guzow-Krzeminska , Serus . & Kukwa sp. nov. Fig. 2C Diagnosis. Species characterised by granular-isidiate thallus, pale grey to grey-beige apothecia, 0-1-septate, ovoid, ellipsoidal or oblong ascospores measuring 7-13 x 3.5-4.5 μm and the presence of micareic acid. Type. POLAND. Rownina Bielska, Bialowieza Primeval Forest, Bialowieza National Park, forest section no 256, Pino-Quercetum , on wood of log, 21 Aug 2015, M. Kukwa 17367a, A. Lubek (holotype UGDA; isotype KTC, ITS GenBank accession number: MN095789, mtSSU GenBank accession number: MK562016, Mcm7 GenBank accession number: MN105897). Description. Thallus crustose, granular-isidiate, indeterminate, endosubstratal to rarely episubstratal in non-isidiate parts and then as a thin greenish film over the substrate or minutely areolate, isidiate; prothallus not seen; areoles up to 0.05 mm in diam., green, soon developing isidia; isidia abundantly branched and coralloid, crowded and forming an almost continuous layer locally over the substrate, but in younger parts of thalli separated, green to olive green (Sedifolia-grey, K+ violet), up to 250 μm tall and 25 μm wide, with a distinct and complete hyphal layer; apothecia rarely developed, white to beige, some patchily grey, up to 0.45 mm in diam., convex; excipulum poorly developed, as a narrow, hyaline zone, hyphae radiating, branched and anastomosing; hymenium up to 50 μm tall, hyaline; epihymenium and hypothecium hyaline; paraphyses of one type, 1-1.5 μm thick, sparse, mostly apically branched and anastomosed, hyaline throughout; asci cylindrical-clavate, 30-45 x 12-15 μm , 8-spored; ascospores, 0-1-septate, ovoid, ellipsoidal or oblong, 11-14 x 3.5-4.5 μm ; pycnidia not seen; crystalline granules (studied in polarised light) present rather sparsely in hymenium (as strands between asci and paraphyses) and abundantly in isidia, soluble in K. Photobiont chlorococcoid, micareoid, cells globose to ellipsoidal, 4-7 μm in diam. Chemistry. Micareic acid detected by TLC. Sedifolia-grey pigment present in outermost parts of some isidia. Habitat and distribution. The species grows on wood (decomposing logs) and acidic bark of trees in various forest communities in well preserved forest. To date, it is known from Belgium, Germany, France, Poland and Romania. Etymology. The name of the new species refers to the presence of isidia and the chemistry of M. prasina . Additional specimens examined. Belgium. Herbeumont, forest by the Semois river, 265 m alt., 49°45'N , 05°13'E , on Quercus tree in forest, 2013, E. Serusiaux 3609 (LG). France. Vosges, Dept . Haut-Rhin, Hohneck, Frankenthal nature preserve, 48°02'N , 07°01'E , 1100 m alt., on dead Fagus in forest, 2013, E. Serusiaux LG DNA 3437 (LG). Germany. Niedersachsen, S of Goslar, Rammelsberg, 360 m alt., 51°53.01'N , 10°25.23'E , trail along Picea forest and brooklet with Acer , Alnus and Betula trees, 12 May 2015, P. & B. van den Boom 53248 (hb. v.d. Boom). Poland. Roztocze Środkowe , Roztoczanski National Park, S of Zwierzyniec village, Bukowa Gora nature reserve, 50°35'47"N , 22°57'48"E , ca. 280 m alt., beech forest, on wood of log, 15 Sept 2015, M. Kukwa 17493 (UGDA); Rownina Bielska, Bialowieza Primeval Forest, Bialowieza National Park, forest section no 256, Carici elongatae - Alnetum , on wood of logs, bark Picea abies and Alnus glutinosa , Aug 2014, M. Kukwa 14030, 14038, 14107, 14112, A. Lubek (KTC, UGDA); ibidem, Circaeo - Alnetum , on wood of log, Aug 2014, M. Kukwa 13299, A. Lubek (KTC, UGDA); ibidem, Tilio - Carpinetum , on wood of log, Aug & Oct 2014, M. Kukwa 13418, 14358, A. Lubek (KTC, UGDA); ibidem, Circaeo-Alnetum , on wood of snag, Oct 2014, M. Kukwa 14243, A. Lubek (KTC, UGDA). Romania. W of Brasov, S of Zarnesti, Praia Craiului National Park, 1350 m alt., 45°31'N , 25°16'E , on Fagus inside forest, 2016, E. Serusiaux LG DNA 6260 & 6265 (LG). Notes. Micarea isidioprasina is an isidiate species of the M. prasina group containing micareic acid as the main secondary metabolite. It is usually sterile and in Poland often grows in similar habitats with M. pauli , a species described in this paper, from which it can be separated with certainty by analyses of secondary metabolites, as the latter contains methoxymicareic acid. Micarea aeruginoprasina and M. nigra also develop similar isidiate thalli, but M. aeruginoprasina has pale cream to pale brown or aeruginose apothecia (often mottled with all colours in the same apothecium) and M. nigra develops dark greyish to black apothecia. When sterile, all three species may be more difficult to separate, especially M. aeruginoprasina which also produces micareic acid ( M. nigra contains methoxymicareic acid), but that species has pale brown isidia. Additionally, the so far known distributions of all three species do not overlap and M. aeruginoprasina and M. nigra are known from the Azores and continental Portugal, respectively. Micareic acid is also the main secondary metabolite in the somewhat morphologically similar M. prasina , but the latter is not isidiate, often richly fertile and its thallus consists of goniocysts ( Czarnota 2007 ; Launis et al. 2019a , b ).