Micarea pauli Guzow-Krzeminska , Lubek & Kukwa

Guzow-Krzeminska, Beata, Serusiaux, Emmanuel, van den Boom, Pieter P. G., Brand, A. Maarten, Launis, Annina, Lubek, Anna & Kukwa, Martin, 2019, Understanding the evolution of phenotypical characters in the Micarea prasina group (Pilocarpaceae) and descriptions of six new species within the group, MycoKeys 57, pp. 1-30 : 1

Micarea pauli Guzow-Krzeminska, Lubek & Kukwa sp. nov. Fig. 2F

Diagnosis.

Species characterised by isidiate thallus, pale grey to grey beige apothecia with Sedifolia-grey pigment, 0-1-septate, ovoid, ellipsoidal or oblong ascospores measuring 7-13 × 3.5-4.5 μm and the presence of methoxymicareic acid.

Type.

Poland. Równina Bielska, Białowieża Forest, Białowieża National Park, forest section no 256, Carici elongatae - Alnetum , on Alnus glutinosa , 17 Aug 2015, M. Kukwa & 17240, A. Łubek (holotype UGDA; isotype KTC, mtSSU GenBank accession number: MK562014, Mcm7 GenBank accession number: MN105912).

Description.

Thallus crustose, 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 evident; areoles up to 0.1 mm in diam., green, soon developing isidia; isidia branched and coralloid, crowded and forming almost a continuous layer over the substrate, but separated in younger parts of thalli, green to olive green, up to 0.5 mm tall and 30 μm wide, with a distinct and complete hyphal layer; apothecia rarely developed (in 2 specimens only), beige with spots of grey pigment, pale grey to grey-beige, up to 0.5 mm in diam., irregular in shape, convex, with a white rim; excipulum as a narrow, hyaline zone, hyphae radiating, branched and anastomosing; hymenium up to 45 μm tall; epihymenium partly olive-grey due to the presence of Sedifolia-grey pigment (K+ violet, C+ violet) confined to the gel matrix; hypothecium hyaline to pale straw coloured in upper part; paraphyses 1-1.5 μm thick, sparse, mostly apically branched and anastomosing, hyaline throughout; asci cylindrical-clavate, 30-35 × 9-12 μm, 8-spored; ascospores, 0-1-septate, ovoid, ellipsoidal or oblong, 7-13 × 3.5-4.5 μm; pycnidia not seen; crystalline granules (studied in polarised light) abundant in hymenium and isidia, soluble in K.

Photobiont chlorococcoid, micareoid, cells globose to ellipsoidal, 4-7 μm in diam.

Chemistry.

Methoxymicareic acid detected by TLC. Sedifolia-grey in apothecia (epihymenium).

Habitat and distribution.

This species is so far known only in Poland from Białowieża Forest, where it grows in deciduous forests on bark of Alnus glutinosa (5 specimens), Tilia cordata (1 specimen) and on wood (2 specimens).

Etymology.

The species is named after our friend, Paweł Czarnota, specialist in the genus who monographed it in Poland.

Additional specimens examined.

Poland. Równina Bielska, Białowieża Forest; Białowieża National Park, forest section no 256, Carici elongatae - Alnetum , on Alnus glutinosa and Picea abies , Aug. 2014, M. Kukwa 13194, 13330, 13345, A. Łubek (KTC, UGDA); ibidem, Tilio-Carpinetum , on Tilia cordata , Aug. 2014, M. Kukwa 14101, A. Łubek (KTC, UGDA); ibidem, Carici elongatae - Alnetum , on Alnus glutinosa , 17 Aug. 2015, M. Kukwa, 17227, A. Łubek (KTC, UGDA, hb v.d. Boom); ibidem, Querco - Piceetum , on Alnus glutinosa , 29 Sept. 2015, M. Kukwa 17544, A. Łubek (KTC, UGDA); ibidem, Peucedano - Pinetum , on Alnus glutinosa , March 2015, M. Kukwa 13308 (KTC, UGDA); Pino-Quercetum , on wood of snag, 1 Oct. 2015, M. Kukwa 17582a, A. Łubek (KTC); Pino-Quercetum , on wood of log, 2 Oct. 2015, M. Kukwa 17619, A. Łubek (KTC, UGDA); Carici elongatae - Alnetum , on Alnus glutinosa , 3 Oct. 2015, M. Kukwa 17621, A. Łubek (KTC, UGDA).

Notes.

Micarea pauli is an isidiate species with Sedifolia-grey pigment in its apothecia. It can be separated from the similar M. isidioprasina , with which it grows in Białowieża Forest, by the presence of methoxymicareic acid.

Micarea aeruginoprasina and M. nigra are also similar in thallus morphology, but they differ in the pigmentation of apothecia. Micarea aeruginoprasina develops pale cream to pale brown or aeruginose apothecia, which are often mottled in colour in one apothecium, whereas in M. nigra the apothecia are dark greyish to black. Without apothecia, they can be difficult to separate from M. pauli , especially M. nigra which also contains methoxymicareic acid ( M. aeruginoprasina produces micareic acid), but so far, M. aeruginoprasina and M. nigra are only known from the Azores and continental Portugal, respectively.

Methoxymicareic acid is the main secondary metabolite, also found in M. byssacea , M. micrococca and other species in the M. micrococca clade ( Fig. 1 ), but those species are never isidiate ( Czarnota 2007; Czarnota and Guzow-Krzemińska 2010; Launis et al. 2019a).

Figures

Figure 1. Maximum likelihood tree based on three-loci dataset. Bootstrap supports ≥ 70 for ML and posterior probabilities ≥ 0.95 (second value) for Bayesian methods are indicated near the branches. The highly supported clades with previously described species represented by numerous sequences are collapsed. Herbarium collection numbers for newly sequenced specimens precede the names of species and type specimens are marked. Newly described species are marked in bold. Micarea micrococca (orange) and M. prasina (blue) clades are indicated with shading. Ancestral states for selected characters reconstructed based on binary or multistate datasets using maximum parsimony (MP) or maximum likelihood methods (ML) are marked for the main clades: M. prasina group, M. micrococca clade and M. prasina clade using red (= present / significant) and white (= absent / insignificant) boxes or? (= uncertain).

Figure 2. Morphology of newly described Micarea species A M. aeruginoprasina (holotype) B M. azorica (holotype) C M. isidioprasina (holotype) D M. microsorediata (holotype) E M. nigra (holotype) F M. pauli (holotype). Scale bars: 200 µm (A−C, E); 300 µm (D, F).