Micarea aeruginoprasina van den Boom, Guzow-Krzeminska , Brand & Serus .

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 aeruginoprasina van den Boom, Guzow-Krzeminska, Brand & Serus. sp. nov. Fig. 2A

Diagnosis.

Species characterised by inconspicuous, pale brownish to moderately brownish, isidiate thallus, branched to coralloid isidia, emarginate, adnate to slightly convex apothecia measuring 0.1-0.5 mm in diam., which are pale cream to pale brown or aeruginose with pigment (Sedifolia-grey, K+ violet, C+ violet) present in hypothecium, (0-)1-septate ascospores measuring 9-14 × 4.5-5.5 µm and the production of micareic acid.

Type.

Portugal. Azores, Terceira, NW of Angra do Heroismo, W of Pico Gordo, Mistério dos Negros (N), trail from Lagoa do Negro to the West, 550 m alt., 38°44.15'N, 27°16.30'W, ± damp Juniperus brevifolia forest, with some young Vaccinium cylindraceum , on Juniperus brevifolia , 28 June 2014, P. & B. van den Boom 51445 (holotype LG; isotypes UGDA, hb v.d. Boom, mtSSU GenBank accession number: MK562024, Mcm7 GenBank accession number: MN105888).

Description.

Thallus indeterminate, inconspicuous, thin, endosubstratal to episubstratal in non-isidiate parts as a thin film over the substrate or minutely granular, pale to moderately brown, isidiate; prothallus not visible; granules vertically proliferating to form isidia; isidia branched to coralloid, crowded or separated, up to 250 μm tall and 25 μm wide, with a distinct and complete hyphal layer; apothecia abundant, adnate to slightly convex, emarginate, rounded to slightly irregular, pale cream to pale brown or aeruginose, often different colours in a single apothecium, 0.1-0.5 mm in diam.; excipulum sometimes paler, instinct; hymenium 40-50 µm high, hyaline; hypothecium hyaline to pale aeruginose brownish (Sedifolia-grey), K+ violet, C+ violet; paraphyses, sparse, branched, 1.0 –1.2(– 1.5) µm wide, tips not widened and not pigmented; asci cylindrical to clavate, 35-40 × 11-14 µm, 8-spored; ascospores ellipsoidal to ovoid, (0‒)1-septate, 9-14 × 4.5-5.5 µm; pycnidia not observed; crystalline granules (studied in polarised light) visible in hypothecium and in thallus, soluble in K.

Photobiont micareoid, cells thin walled, 6-9 µm in diam., clustered in compact groups.

Chemistry.

Micareic acid detected by TLC. Sedifolia-grey in apothecia (hypothecium), its presence sometimes indistinct.

Habitat and distribution.

In the type locality Micarea aeruginoprasina grows abundantly on trunks of Juniperus brevifolia , in a subnatural degradated forest, dominated by J. brevifolia shrubs and trees. In other localities, it was found on Cryptomeria and Erica trunks, also in forested areas.

The new species is only known from the island Terceira in the Azores, where it is known from several localities.

Etymology.

The epithet refers to the often aeruginose colour of the apothecia and the resemblance in secondary chemistry to M. prasina .

Additional specimens examined.

Portugal. Azores, Terceira, NW of Angra do Heroismo, south edge of Reserva Florestal da Lagoa das Patas, area around a pond 'Lagoa das Patas’, mature Cryptomeria trees and some Camellia shrubs, on Cryptomeria , 38°43.01'N, 27°17.32'W, 520 m alt., 28 June 2014, P. & B. van den Boom 51878 (hb v.d. Boom); NW of Angra do Heroismo, NNE of Santa Bárbara, Serra de Santa Bárbara, road to the summit, forests with mainly Cryptomeria trees, trees at edge of forest, on Cryptomeria , 38°43.49'N, 27°19.33'W, 800 m alt., 1 July 2014, P. & B. van den Boom 51622 (hb v.d. Boom); NE of Serreta, north trail to Lagoínha, forest with Cryptomeria japonica , Myrica faya , Erica , etc., on Erica , 38°45.28'N, 27°20.50'W, 500 m alt., 2 July 2014, P. & B. van den Boom 51691 (hb v.d. Boom).

Notes.

This species is unique within the group due to the presence of the Sedifolia-grey pigment in hypothecium. It is similar to M. prasina because of its production of micareic acid, but the latter has Sedifolia-grey pigment in the epihymenium and its thallus consists of goniocysts (isidiate in M. aeruginoprasina ). However, it is not closely related to M. prasina , being resolved as basal in the M. prasina clade and the sequences of their molecular markers are very different. In the Azores archipelago, the most widespread prasina -like species is M. azorica , newly described in this paper, which, however, is not isidiate and contains Superba-brown in the apothecia. Micarea aeruginoprasina resembles M. byssacea , which can have somewhat the same coloured and adnate apothecia; however, M. byssacea is not isidiate, contains methoxymicareic acid and the apothecial pigment is absent in hypothecium ( Czarnota and Guzow-Krzemińska 2010). Morphologically, the new species is similar to M. levicula , especially due to the finely isidiose thallus and the adnate apothecia, which are, however, paler in M. levicula and that species contains gyrophoric acid ( Coppins 1983; Brand et al. 2014).

Micarea isidioprasina , M. nigra and M. pauli also have isidiate thalli, but only M. aeruginoprasina has pale cream to pale brown or aeruginose apothecia. Micarea isidioprasina and M. pauli are often sterile and, to date, M. aeruginoprasina and M. nigra have always been found with apothecia, but, based only on the thallus characters, M. nigra and M. pauli can be distinguished due to the production of methoxymicareic acid and M. isidioprasina has green isidia (shades of brown in M. aeruginoprasina ).

Figures

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).